Friday, January 27, 2023

Laser Pulses Divert Lightning Strikes


This graphic shows the central part of a thunderstorm where air is moving upward rapidly (up-draft), as the cloud accumulates a negative charge (electrons) creating lightning. Temperatures in this cloud range from +5 to -13 degrees Fahrenheit / -15 to -25 degrees Celsius. (Graphic Sources: Wikipedia.org, By U.S. Government, National Weather Service - http://www.lightningsafety.noaa.gov/science/science_electrification.shtml (in August 2019, https://www.weather.gov/safety/lightning-science-scienceintro), Public Domain, https://commons.wikimedia.org/w/index.php?curid=53463755)

By Glenn A. Walsh

Reporting for SpaceWatchtower

Scientists in Switzerland have now demonstrated that laser pulses can divert lightning strikes. As the first major improvement to Benjamin Franklin's Lightning Rod, this has the potential to provide much greater protection to large infrastructure such as launch-pads and airports.

The experiment took place from 2021 July 21 to September 30 on Santis Mountain, on the northeastern tip of the Swiss Alps, using a green, infrared laser. At the summit of the mountain (altitude 8,200 feet / 2,500 meters), the laser was mounted near a 407 -foot / 124-meter telecommunications tower (which has its own Lightning Rod) and aimed at passing storm-clouds in the sky.

By firing the laser rapidly, in short, intense pulses (1,000 times per second), during thunderstorms, they were able to create a path for the lightning to specifically avoid striking the tower's tip (where the traditional Lightning Rod is located). In this experiment, lightning avoided the tower's tip four times within six hours.

Normally, this tower is struck by lightning about 100 times in one year. During the trial period, lightning struck the tower 12 times, while the laser was not being used.

Hence, the unpredictability of lightning strikes can lead to billions of dollars of damage each year, as well as occasional lives lost. So, finding a modern improvement to the Lightning Rod could save resources, as well as some lives.

This research was led by physicist Aurelien Houard of the French National Center for Scientific Research's Applied Optics Laboratory in Paris. The scientists' findings were published in the 2023 January 16 edition of the scientific journal Nature Photonics.

According to the published study, “Although this research field has been very active for more than 20 years, this is the first field-result that experimentally demonstrates lightning guided by lasers.” With only a couple exceptions, previous work had only occurred in physics laboratories, since 1974.

Past attempts at field tests of laser deflection of lightning in New Mexico (2004) and Singapore (2011) had not been successful. Although the reason for the past failures is not certain, the researchers speculate that the laser beams in the past experiments had not been as rapid as the laser pulses in the Swiss experiment.

Lightning is an electrostatic discharge (generated by the friction of ice clumps and rain drops in storm-clouds), within a cloud, between two clouds, or between the cloud and the ground. As negatively-charged electrons gather at a storm-cloud's base and attract a ground's positive charge, the electrons begin to overcome air resistance causing the ionization of air in a charged flow or path to the ground – a lightning bolt. This dissipates and temporarily neutralizes the charge with the release of approximately a gigajoule of energy.

Every second about a hundred lightning flashes can be found some place on our planet, or between clouds.

Lightning Rods protect buildings and other structures by providing a path for the electrical charge to more easily reach the ground, rather than traveling through the air for the entire distance. But, the protection is limited, due to the height of a Lightning Rod.

To extend the protection from lightning, the new laser pulses are used to provide a new pathway to the ground. The laser beam rapidly heats air molecules, which creates a channel of less dense air and an easier pathway to the ground. Whether a traditional Lightning Rod, or this new system of laser pulses, electricity always wants to follow the path of least resistance.

Lightning bolts release a wide range of electromagnetic radiation including radio waves (which can be heard as crackling and / or a large clap on AM and Short-Wave radios), light waves, and X-Rays. Lightning causes thunder, the sound from a shock wave in the vicinity of the electrical discharge, as air experiences a sudden increase in pressure.

Many people are aware of the “5-second rule”. When you see a lightning strike, count each second until thunder is heard. When you divide the total number of seconds between lightning and thunder by five, the result is an approximate distance in statute miles of the lightning bolt (and often the center of the thunderstorm) from your current location.

Earth is not the only planet with lightning. Jupiter and Saturn have been observed with lightning strikes, with major lightning bolts seeming to be common on Jupiter. Although not confirmed, NASA and Russian space probes suggest that lightning may also exist in the very dense and toxic atmosphere of Venus.

The original Lightning Rod was invented in 1750 by American Founding Father Benjamin Franklin of Pennsylvania, who is considered America's first true scientist. While a lightning bolt may strike a Lightning Rod, the actual purpose of a Lightning Rod is to bleed-off excess electrical charge to the ground where the excess charge is dissipated, so the charge does not build-up to a dangerous lightning strike.

So, this new laser system would, indeed, be used to attract lightning strikes, when a Lightning Rod does not, or is not close enough to, bleed-off enough electrical charge. With extreme weather becoming more prevalent, due to Climate Change, this new type of protection from lightning could be used to protect many more tall structures.

Internet Links to Additional Information ---

Published Research - Abstract & Main Article: "Laser-guided lightning":

 Link >>> https://www.nature.com/articles/s41566-022-01139-z?utm_medium=affiliate&utm_source=commission_junction&utm_campaign=CONR_PF018_ECOM_GL_PHSS_ALWYS_DEEPLINK&utm_content=textlink&utm_term=PID100052172&CJEVENT=b24eceef9d8f11ed817f3b8a0a82b836

Laser: Link >>> https://en.wikipedia.org/wiki/Laser

Lightning: Link >>> https://en.wikipedia.org/wiki/Lightning

Lightning Rod: Link >>> https://en.wikipedia.org/wiki/Lightning_rod 

Benjamin Franklin Invents Lightening Rod: Link >>> https://www.fi.edu/history-resources/franklins-lightning-rod

Tesla Coil (Artificial Lightning): Link >>> https://buhlplanetarium2.tripod.com/Buhlexhibits.htm#teslacoil 

Source: Glenn A. Walsh Reporting for SpaceWatchtower, a project of Friends of the Zeiss          

               Friday, 2023 January 27.


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Glenn A. Walsh, Informal Science Educator & Communicator                                                               (For more than 50 years! - Since Monday Morning, 1972 June 12):
Link >>> http://buhlplanetarium2.tripod.com/weblog/spacewatchtower/gaw/
Electronic Mail: < gawalsh@planetarium.cc >
Project Director, Friends of the Zeiss: Link >>> http://buhlplanetarium.tripod.com/fotz/
SpaceWatchtower Editor / Author: Link >>> http://spacewatchtower.blogspot.com/
Formerly Astronomical Observatory Coordinator & Planetarium Lecturer, original Buhl Planetarium & Institute of Popular Science (a.k.a. Buhl Science Center), America's fifth major planetarium and Pittsburgh's science & technology museum from 1939 to 1991.
Formerly Trustee, Andrew Carnegie Free Library and Music Hall, Pittsburgh suburb of Carnegie, Pennsylvania, the fourth of only five libraries where both construction and endowment funded by famous industrialist & philanthropist Andrew Carnegie.
Author of History Web Sites on the Internet --
* Buhl Planetarium, Pittsburgh: Link >>>  http://www.planetarium.cc  Buhl Observatory: Link >>>  http://spacewatchtower.blogspot.com/2016/11/75th-anniversary-americas-5th-public.html
* Adler Planetarium, Chicago: Link >>> http://adlerplanetarium.tripod.com
* Astronomer, Educator, Optician John A. Brashear: Link >>> http://johnbrashear.tripod.com
* Andrew Carnegie & Carnegie Libraries: Link >>> http://www.andrewcarnegie.cc

* Other Walsh-Authored Blog & Web-Sites: Link >>> https://buhlplanetarium.tripod.com/gawweb.html

 

Wednesday, January 11, 2023

$4.48 Million Mars Exhibit Opens in Pittsburgh

               

Meteorite from the planet Mars, on display as part of the new exhibit, Mars: The Next Giant Leap, at The Carnegie Science Center in Pittsburgh. A Moon rock, found during the 1971 mission of Apollo 15, is also on display; one of the astronauts to land on the Moon during this mission was James B. Irwin, a native of the Beechview section of Pittsburgh.

(Image Source: Friends of the Zeiss; Photographer: Glenn A. Walsh)

(More photographs of exhibit at this link: Link >>> https://andrewcarnegie.tripod.com/csc/pix/mars/ )

 By Glenn A. Walsh

Reporting for SpaceWatchtower

Late last year, a new, 7,400 square-foot / 2,255.52 square-meter exhibit, titled, Mars: The Next Giant Leap, opened in The Carnegie Science Center in Pittsburgh. Divided in seven experiential zones, the exhibit focuses on future human exploration of, and possible settlement on, the Red Planet.

The new exhibit, which cost an estimated $4.48 million, includes a slice of a meteorite that scientists believe came from the planet Mars. The rock, from which the meteorite slice came from, probably fell to Earth after being knocked off of Mars by a larger meteorite or asteroid which hit Mars in the distant past.

Also displayed is a Moon rock (Lunar Sample #15499), on loan from NASA for at least five years, collected by Apollo 15 astronauts in 1971. One of the Apollo 15 astronauts to land on the Moon was James B. Irwin, a native of the Beechview section of Pittsburgh.

Other meteorites are on display, nearby, in the lobby of the Henry Buhl, Jr. Planetarium. One large meteorite, which the public can touch, is the fifth largest fragment of the large meteorite that created Meteor Crater in Arizona; this particular meteorite, Property of the City of Pittsburgh, was first displayed at Pittsburgh's original Buhl Planetarium and Institute of Popular Science in 1939. Another meteorite on display was collected by University of Pittsburgh Professor William Cassidy, during one of his expeditions to Antarctica.

Mars Closest Approach to Earth & Opposition

Mars: The Next Giant Leap opened to the public on Saturday, 2022 November 19, shortly before the bi-annual close approach of Mars to the Earth. Actually, Earth and Mars reach the closest point to each other every two years and two months.

The planet Mars was at its closest approach to Earth on Wednesday, 2022 November 30 at 9:00 p.m. Eastern Standard Time (EST) / December 1 at 2:00 Coordinated Universal Time (UTC). Mars was at its brightest in Earth's night sky at a Visual Magnitude of -1.8 with the Martian disk appearing as large as 17.2 seconds-of-arc in diameter. At that time, Mars was just 4.5 light-minutes away (distance of 0.544 Astronomical Unit / 50,567,959 statute miles / 81,381,241.409 kilometers).

Mars was in Opposition (with the Earth lying directly between Mars and the Sun - Mars visible all-night-long, approximately local sunset to local sunrise) on Thursday, 2022 December 8 at 1:00 a.m. EST / 6:00 UTC. The one week difference between Mars' closest approach to Earth and Mars' Opposition is due to the asymmetric nature of the Martian orbit.

The Red Planet appeared fairly close to the December Full Moon (“Cold Moon” on Wednesday, 2022 December 7 at 11:08 p.m. EST / December 8, 4:08 UTC). In fact, the Moon completely covered the planet Mars, in what astronomers call an Occultation, on Wednesday, 2022 December 7 at 11:00 p.m. EST / December 8 at 4:00 UTC. Amazingly, this occurred when Mars and Earth's Moon were both opposite the Sun and 100 per-cent illuminated by the Sun, but far enough north of the Ecliptic that there was no Lunar Eclipse / Eclipse of the Moon.

This Lunar Occultation was visible, weather-permitting, in most of the United States (except Alaska), Canada, Greenland, northwestern portion of Mexico, Svalbard (archipelago part of Norway), much of Europe, western portion of Russia, and a portion of northern Africa. For other observers, Mars was in Conjunction with the Full Moon (Mars 0.5 degree south of the Moon).

Today, Mars is still bright in the evening sky, but through much of the month Mars' brightness is beginning to wane. Although it will still be pretty bright at the end of January, the brightness will be 50 per-cent dimmer than at the beginning of the month as Earth and Mars separate. Look for Mars high in the east in evening twilight, and in the south later in the night, weather-permitting.

Again, there will be another Lunar Occultation of Mars late on Monday Evening, 2023 January 30 at 11:00 p.m. EST / January 31 at 4:00 UTC (Moon Phase: Waxing Gibbous). This Occultation will be visible, weather-permitting, in the southern portion of the United States, Mexico, Central America, Caribbean, northern section of South America, and most of Polynesia (but not New Zealand). Other areas will see Mars as little as 0.1 degree north of the Moon.

                    

A simulated Martian landscape, where visitors can control miniature Mars rovers, while trying to search for evidence of past life.

(Image Source: Friends of the Zeiss; Photographer: Glenn A. Walsh)

(More photographs of exhibit at this link: Link >>> https://andrewcarnegie.tripod.com/csc/pix/mars/ )

Exhibit Experiential Zones

The Carnegie Science Center used focus groups of students and North Side, Pittsburgh residents, as well as seeking input from local business leaders, to help design the new exhibit. In the focus groups, questions such as “Why go to Mars?” and “How do you form a new society on the planet?” were asked by the participants. Future input from Science Center visitors will help further develop parts of the exhibit.

The following are the seven experiential zones of the new exhibit ---

  • View from Mars – This zone provides images of the Martian landscape and perspectives of Earth. It talks about how robotic exploration of Mars, as well as science-fiction and pop-culture, has influenced our view of the Red Planet.

  • Climatology – This zone looks at how climates produce the conditions for life to arise. This area considers the climate systems of Mars and Earth, the abilities of each to sustain life, and what similar conditions may be found on the two planets. This zone includes a meteorite scientists believe originated on Mars.

  • Martian Garden - Greening of the Red Planet is the focus of this zone. Sustainability and resource management are vital for the survival of humans, and whatever other animals are brought to Mars. Three Pods show Soiless Growing (very little soil exists on Mars), Soil Growing, and Biotechnology on Mars.

  • Martian Living – This zone looks at life on Mars, from the viewpoint of possible Mars settlers. This area looks at technology needed to support human living on Mars. This area includes a Moon rock (Lunar Sample #15499), on loan from NASA for at least five years, which was collected by the two astronauts who landed on the Moon in 1971 during the mission of Apollo 15; one of these astronauts was James B. Irwin, a native of the Beechview section of Pittsburgh. This area also talks about possible challenges from Martian Living such as a weakened or lost human immune system (from a sterile environment), how bones may become denser and more brittle (due to lower gravity), and whether more prevalent DNA mutations (from DNA damage caused by greater Cosmic Rays) could turn setters into a new species—true Martians!

  • Dream Big: Space – This zone includes an imagined Martian settlement, which exhibit visitors can help design. Visitors' input will be immediately displayed on a digital model, and over-time may be added to the physical model. This area asks several questions about possible future Martian settlements, including, “In an isolated world, will we guarantee the right to return to Earth?”

  • Pittsburgh in Mars – This zone looks at humanity's future in Outer Space. In particular, it shows how Pittsburgh academic and corporate research is helping move humans into Outer Space and onto Mars. This area includes profiles of NASA Space Shuttle Astronaut Mike Fincke, University of Pittsburgh Engineering Professor Albert To, Carnegie Mellon University Robotics Professor Howie Choset, Carnegie Mellon University (CMU) Lead Systems Engineer Siri Maley (CMU's IRIS Rover to travel to the Moon; IRIS is Siri spelled backwards!), Carnegie Mellon University Civil and Environmental Engineering Professors Burcu Akinci and Mario Berges, Carnegie Mellon University Creative Technologist Angelica Bonilla Fominaya (spacesuit user interface), Howmet Aerospace Vice President Markus Heinimann, Arconic Corporation (aluminum-lithium low-weight, alloy plates for NASA spacecraft), and Kennametal Corporation (metal-cutting tools for NASA spacecraft).

  • Search for Life – Scientists believe that, at one time, the Martian climate was similar to Earth's current climate. So, Mars is one of the most logical places to look for evidence of past life in our Solar System. This also looks at possible life impacts on climate. In this area, visitors can control miniature Martian rovers on a simulated Martian landscape, in a search for signs of life.

More on The Carnegie Science Center.

The Carnegie Science Center is located on the Lower North Side of Pittsburgh, on the North Shore of the Ohio River about a mile from Downtown Pittsburgh's Golden Triangle. The Science Center building is located between Acrisure Stadium (home of the Pittsburgh Steelers and the University of Pittsburgh Panthers football teams) and Rivers Casino and Hotel. The Carnegie Science Center is about a block south of the Allegheny Light Rail Rapid Transit Station (served by the "T" Red, Blue, and Silver Lines) of Pittsburgh Regional Transit (a.k.a. Port Authority of Allegheny County Transit). Two parking lots are available for visitors coming by automobile.

The Carnegie Science Center is open six days a week, 10:00 a.m. to 5:00 p.m. Eastern Time, Wednesday through Monday; the building is closed on Tuesday. Admission charges are --- Adults: $20; Senior Citizens (age 65 and greater): $15; Children (ages 3 to 12): $12; and Toddlers (age 2 and under): No Charge.

Adjacent to this Mars exhibit, on the second floor of The Carnegie Science Center, is the recently renovated Henry Buhl, Jr. Planetarium. On the day of the author's visit (Wednesday, 2022 November 23), four planetarium sky shows and one laser-light concert were performed for the public in the planetarium theater: “Story Time Under the Stars” (11:00 a.m. - geared to ages 6 and younger and their families), “Two Small Pieces of Glass” (12:00 Noon), “Stars Over Pittsburgh” (1:00 p.m.), “Laser Galactic Odyssey” (2:00 p.m.), “Beginner's Guide to the Universe” (3:00 p.m.), and “Big Astronomy” (400 p.m.). Each show lasts about a half-hour, and all planetarium shows are included in the General Admission Fee; laser-light shows (such as the 2:00 p.m. show) require an additional admission ticket.

Exhibits in the Henry Buhl, Jr. Planetarium Lobby include the fifth largest meteorite fragment (iron-nickel meteorite weighing 746 pounds / 340 kilograms) from Arizona's Barringer Meteor Crater. Visitors are encouraged to touch this meteorite. Also on display is a smaller meteorite found in Antarctica by University of Pittsburgh Professor William A. Cassidy.

In the Henry Buhl, Jr. Planetarium Lobby, visitors can also determine their weight on Mars, as well as their weight on Earth, the Moon, and Venus, on the historic Fairbanks-Morse Planetary Weight Scale. As the Arizona meteorite fragment and the Fairbanks-Morse scale were both originally displayed at the dedication of the original Buhl Planetarium and Institute of Popular Science on Tuesday Evening, 1939 October 24, both are the Property of the City of Pittsburgh.

On Saturday, 2022 October 15 just four blocks north of The Carnegie Science Center, a $2.7 million Moonshot Space Museum, regarding robotic missions to the Moon, opened. The museum is adjacent to, and operated by, Astrobotic Technology, Inc., which plans to send a robotic rover to the Moon this year. Near the end of this blog-post is the link to a blog-post describing the new Moonshot Space Museum.

  

The planet Mars, as displayed in a classic, display-case exhibit in the Hall of the Universe (1950s to 1994) at the original Buhl Planetarium and Institute of Popular Science / Buhl Science CenterAmerica's fifth major planetarium and Pittsburgh's science and technology museum from 1939 to 1991.

.(Image Source: Friends of the Zeiss; Photographer: Francis G. Graham, Professor Emeritus of Physics, Kent State University)

Mars Often Featured at the Original Buhl Planetarium

The predecessor of The Carnegie Science Center was the original Buhl Planetarium and Institute of Popular Science (a.k.a. Buhl Science Center), America's fifth major planetarium and Pittsburgh's science and technology museum from 1939 to 1991. The original Buhl Planetarium building, now used by the Children's Museum of Pittsburgh, is located in Allegheny Center, one mile northeast of The Carnegie Science Center.

Mars was often the topic of science programming at the original Buhl Planetarium.

For decades (1950s to 1994), a classic, display-case exhibit showing the planet Mars was displayed in the Hall of the Universe of the original Buhl Planetarium. This exhibit showed the topography of Mars, as determined by telescopic images of Mars taken in the 1950s.

Two weight scales at the original Buhl Planetarium helped visitors determine what they would weigh on Mars: Fairbanks-Morse Planetary Weight Scale (in addition to Mars, visitors could determine their weight on Earth, Earth's Moon, and Venus on this scale); Toledo Planetary Weight Scale (three additional Toledo scales allowed visitors to determine their weight on Earth, the Moon, and Jupiter). The historic Fairbanks-Morse scale (Property of the City of Pittsburgh) continues to be available to the public in the Henry Buhl, Jr. Planetarium Lobby on the second floor of The Carnegie Science Center.

From time-to-time, the Buhl Planetarium sky show performance, in the original Theater of the Stars, would be about Mars. This includes a show titled, “The Red Planet Mars” in April of 1988, ahead of the Perihelic Opposition of Mars on 1988 September 28 (closest approach to Earth: 1988 September 22). The historic Zeiss II Planetarium Projector (Property of the City of Pittsburgh), which presented all planetarium sky shows from 1939 to 1991, is now on static display in the Space Place exhibit in The Carnegie Science Center's first-floor Atrium Gallery.

“Mars in 3-D”, a popular motion picture produced by NASA, was often shown to the general public in Buhl Planetarium's Little Science Theater (250-seat Lecture Hall); each visitor attending the film was given a pair of 3-D glasses to view the production. This 1979 film included 3-D images of Mars, taken by the Viking 1 and Viking 2 spacecraft, beginning in the Summer of 1976.

Mars was often the featured object shown to the public, particularly when Mars was close to Earth, in the original Buhl Planetarium Astronomical Observatory. Buhl's Astronomical Observatory was open for public observing every Friday evening 7:30 to 10:30 p.m. Eastern Time (ET), weather-permitting, year-round---also, some Thursday, Saturday, and Sunday evenings, weather-permitting, during the months of November through February (except the evenings of Christmas Eve and Christmas Day, when the building was closed) each year.

In addition to the opening of Mars: The Next Giant Leap exhibit on November 19, November 19 also marked the 81st anniversary (Wednesday Evening, 1941 November 19) of the Astronomical Observatory at the original Buhl Planetarium and Institute of Popular Science. The Astronomical Observatory's primary instrument was a rather unique, and now historic, 10-inch Siderostat-type Refractor Telescope (Property of the City of Pittsburgh).

The original Buhl Planetarium / Buhl Science Center also displayed a Moon Rock, collected by the Apollo astronauts, for the general public twice. The first time was in the Spring of 1970, shortly after the beginning of the manned lunar landings. The second time was in the Summer of 1989, in commemoration of the 20th anniversary of the Apollo 11 landing.

ADDENDUM - More Photographs of the new Mars: The Next Giant Leap Exhibit:

Link >>> https://andrewcarnegie.tripod.com/csc/pix/mars/

Internet Links to Additional Information ---

Mars: The Next Giant Leap Exhibit at The Carnegie Science Center:

Link >>> https://carnegiesciencecenter.org/exhibits/mars/

Photographs of some additional exhibits at The Carnegie Science Center:

Link >>> https://andrewcarnegie.tripod.com/csc/photoalbum.html

Mars: Link >>> https://en.wikipedia.org/wiki/Mars

The Carnegie Science Center: Link >>> https://carnegiesciencecenter.org/

Historic Buhl Planetarium & Institute of Popular Science / Buhl Science Center:

Link >>> http://www.planetarium.cc/

NASA  Apollo 15  Astronaut James B. Irwin, Pittsburgh native who landed on Moon:

Link >>> https://buhlplanetarium2.tripod.com/bio/Pghastronauts.html#irwin

Related Blog-Posts ---

"Moonshot Space Museum Opens in Pittsburgh." Thur., 2022 Oct. 20.

Link >>> https://spacewatchtower.blogspot.com/2022/10/moonshot-space-museum-opens-in.html

"Science Museums Rebound After Worst of Pandemic." Tue., 2022 Sept. 27.

Association of Science & Technology Centers (ASTC) 2022 Conference in Pittsburgh

Link >>> https://spacewatchtower.blogspot.com/2022/09/science-museums-rebound-after-worst-of.html


NASA Astronaut & Beechview Native James B. Irwin

"Pittsburgh Museum Displays Historic Apollo 11 Moon Mission Artifacts." Wed., 2018 Oct. 24.


"Mars Rover Sees Mystery Rock Suddenly Appear." Mon., 2014 Jan. 20.

By Francis G. Graham, Professor Emeritus of Physics, Kent State University
Reporting for SpaceWatchtower

Source: Glenn A. Walsh Reporting for SpaceWatchtower, a project of Friends of the Zeiss          

               Wednesday, 2023 January 11.


                             Like This Post?  Please Share!

           More Astronomy & Science News - SpaceWatchtower Twitter Feed:
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gaw

Glenn A. Walsh, Informal Science Educator & Communicator                                                               (For more than 50 years! - Since Monday Morning, 1972 June 12):
Link >>> http://buhlplanetarium2.tripod.com/weblog/spacewatchtower/gaw/
Electronic Mail: < gawalsh@planetarium.cc >
Project Director, Friends of the Zeiss: Link >>> http://buhlplanetarium.tripod.com/fotz/
SpaceWatchtower Editor / Author: Link >>> http://spacewatchtower.blogspot.com/
Formerly Astronomical Observatory Coordinator & Planetarium Lecturer, original Buhl Planetarium & Institute of Popular Science (a.k.a. Buhl Science Center), America's fifth major planetarium and Pittsburgh's science & technology museum from 1939 to 1991.
Formerly Trustee, Andrew Carnegie Free Library and Music Hall, Pittsburgh suburb of Carnegie, Pennsylvania, the fourth of only five libraries where both construction and endowment funded by famous industrialist & philanthropist Andrew Carnegie.
Author of History Web Sites on the Internet --
* Buhl Planetarium, Pittsburgh: Link >>>  http://www.planetarium.cc  Buhl Observatory: Link >>>  http://spacewatchtower.blogspot.com/2016/11/75th-anniversary-americas-5th-public.html
* Adler Planetarium, Chicago: Link >>> http://adlerplanetarium.tripod.com
* Astronomer, Educator, Optician John A. Brashear: Link >>> http://johnbrashear.tripod.com
* Andrew Carnegie & Carnegie Libraries: Link >>> http://www.andrewcarnegie.cc

* Other Walsh-Authored Blog & Web-Sites: Link >>> https://buhlplanetarium.tripod.com/gawweb.html

 

Sunday, January 1, 2023

Leap-Second to Make-Way for Leap-Minute?

 

Time.gov screen-shot from the last Leap-Second inserted in the civil time scale. In this case, displayed is Coordinated Universal Time (UTC), used internationally and by scientists. This time was equivalent to 6:59:60 p.m. Eastern Standard Time (EST) on Saturday Evening, 2016 December 31. (Image Sources: National Institute of Standards and Technology, Wikipedia.org, By US Government / NIST - Screen Grab from web display of www.time.gov, Public Domain, https://commons.wikimedia.org/w/index.php?curid=54655717)

By Glenn A. Walsh

Reporting for SpaceWatchtower

For the last 50 years, some calendar years have ended with a Leap-Second, an additional second added to keep clocks in-sync with the slowing rate of the Earth's rotation. However, scientists have decided to end the practice of adding Leap-Seconds, by or before 2035.

What is a Leap-Second ?

As mentioned, a Leap-Second is an additional second inserted into the civil time scale (which had been converted to the more accurate and consistent Atomic Time), to keep our clocks close to the time as determined by the Earth's rotation rate. The Leap-Second is used to keep Atomic Time synchronized with Astronomical Time or Universal Time.

As of 2022 December, Atomic Time has been between 15 and 20 milliseconds ahead of Astronomical Time. One millisecond is one-thousandth of one second.

Actually Leap-Seconds were designed to be either positive or negative, depending on the uncertain nature of the Earth's rotation. However, to-date, only 27 positive Leap-Seconds have been inserted into the civil time scale since 1972, the last one added on 2016 December 31.

Also, the Leap-Second was designed to be added or subtracted from the civil time scale on either June 30 or December 31, or both. One Leap-Second was added both on June 30 and December 31 in the first year it was instituted, 1972. Although most Leap-Seconds have been added on December 31, 11 Leap-Seconds have been inserted on June 30, the last added on 2015 June 30.

Sometimes, when a Leap-Second is added on December 31, the famous New York City Times Square Ball-Drop holds the ball for an additional second, for the Leap-Second. However, this is just for show. The Leap-Second, whether inserted on June 30 or December 31, is always added at 23:59:60 Coordinated Universal Time (UTC - time used internationally and by scientists), which is the equivalent of 6:59:60 p.m. Eastern Standard Time (EST).

The Times Square Ball-Drop harkens back to the early days of marine navigation. Time Balls, mostly at astronomical observatories and other significant marine navigation-related buildings, would drop each day at local Noon, so ships off-shore could accurately set their chronometers. To determine the accurate Longitude at sea. mariners must have the accurate time.

Why Have a Leap-Second in the First Place ?

Astronomers in the 19th century used the stars to tell-time. A special Meridian Transit Telescope would be used to determine the precise time when a star had returned to the same location in the sky, the following day. Samuel Pierpont Langley, a future Secretary of the Smithsonian Institution, sold the precise time to the railroads via telegraph transmission beginning in 1869, when he was Director of Pittsburgh's Allegheny Observatory. This led to the creation of geographic Time Zones in 1883.

However, the Earth's rate of rotation on its axis (which causes day and night), measured by astronomers, is not as consistent as the more accurate time created by our atomic clocks. So, it was decided in 1972 to change the clocks, to more agree with the Earth's rotation, which is measured as Astronomical Time or Universal Time (UT or UT1). Coordinated Universal Time (UTC) is then converted to the civil time scales of the world, such as Eastern Time (ET) and the other 23 world time zones.

This was fine for the last 50 years. When the Earth's rate of rotation slowed to the point where Atomic Time was ahead by 0.9 second, a Leap-Second would be added to remedy the discrepancy. Actually, the Leap-Second is usually added once Atomic Time is ahead by 0.6 second, so the discrepancy does not approach the one second deviation. When a Leap-Second is added, automatically clocks come to be ahead of Astronomical Time by 0.4 second; so, the next Leap-Second would not be added until clocks lose an additional 1.0 second of time.

An organization called the International Earth Rotation and Reference Systems Service (IERS) makes the decision when a Leap-Second needs to be added (or subtracted), six months before implementation. In addition to notifying other scientists and the media of the decision, U.S. National Institute of Standards and Technology short-wave radio stations WWV (Fort Collins, Colorado) and WWVH (Kekaha, Hawaii), which broadcast precise time-of-day signals to the general public, transmit an hourly announcement of the Leap-Second change to take-place.

Why Eliminate Leap-Seconds Now ?

Remember the “Y2K” scare of 1999? Moving from “99” to “00”, on computers which represented the year with only two digits, was predicted to confuse and compromise some computer applications. Preparations and preventive measures were taken and few problems occurred. Regrettably, two-digit year expressions can still be found in some applications.

In the 21st century, Leap-Seconds have proven to be quite disruptive to computers, particularly with applications requiring time-stamping or time-critical process control. This includes cellular telephone networks and GPS (Global Positioning System), as well as aviation and satellite navigation systems – any system that requires precise time-keeping. System failures and anomalies can be caused by the insertion of a Leap-Second.

Scientists have been considering the elimination of the Leap-Second since 2015. On 2022 November 18 the final decision was made at a general conference in France of the International Bureau of Weights and Measures (BIPM), which is responsible for international time-keeping.

The United States was one of the nations which voted to eliminate the Leap-Second. This is no surprise considering how dependent our nation has become to computer and other high-technology systems.

What Are Alternatives to the Leap-Second ?

At this conference, it was decided that by or before 2035, insertion of Leap-Seconds would end. When, exactly this would take place, and what would be the alternative, has not yet been determined. Another international conference in 2026 would need to iron-out those details.

It is anticipated that, without Leap-Seconds, the difference between Atomic Time and Astronomical Time would continue to increase, but not by an alarming rate. It is predicted that it would take 50-to-100 years before such a difference would add-up to one minute. It could take up-to five millenia for the difference to become as large as one hour!

So, what are possible alternatives? One idea is to add a Leap-Minute, when needed, every 50-to-100 years. Another alternative is similar, but instead of calling it a Leap-Minute, simply “smearing” the last minute of a particular year into two minutes. Again, so far no specific alternative has been endorsed by scientists.

Of course, this assumes that the Earth's rotation rate will continue slowing. But what if the Earth surprises us? If the Earth's rotation rate should suddenly speed-up, no change may be necessary or a negative Leap-Minute (subtracting a minute at the end of a year) could become necessary.

Scientists still have much to learn about the rotation rate of celestial bodies, including our own planet. Subtle changes could affect a planet's rotation rate. In the case of the Earth, the Moon's gravity which affects ocean tides could change, as the Moon very, very gradually moves farther from our planet each year.

The change in the distribution of the Earth's mass from shifts in our planet's molten interior, perhaps caused by greater volcanic activity, could affect the Earth's rotation rate. Some scientists suggest that Climate Change, with warmer air and melted water moving closer to the poles, may cause the Earth to spin faster!

Once Leap-Seconds no longer occur (by or before 2035), astronomers will need to adjust times, by a specific amount for the time period of their observations, to ensure that their telescopes and other instruments can find the star, planet, or other celestial body they wish to study. No doubt, astronomical almanacs will need to begin reporting on the time corrections needed by these scientists, as well as by amateur astronomers.

At any rate, there is no Leap-Second planned for the end of 2022. And, there may never be a Leap-Second again! We will just have to keep watching our time.

Internet Links to Additional Information ---

Leap-Second ---

(National Institute of Standards and Technology): Link >>> https://www.nist.gov/pml/time-and-frequency-division/leap-seconds-faqs

(Wikipedia): Link >>> https://en.wikipedia.org/wiki/Leap_second

International Atomic Time (TAI): Link >>> https://en.wikipedia.org/wiki/International_Atomic_Time

Astronomical Time >>> https://en.wikipedia.org/wiki/24-hour_clock

Universal Time (UT / UT1): Link >>> https://en.wikipedia.org/wiki/Universal_Time

Coordinated Universal Time (UTC):

Link >>> https://en.wikipedia.org/wiki/Coordinated_Universal_Time

Astronomical Time Balls: Link >>> https://en.wikipedia.org/wiki/Time_ball

Samuel Pierpont Langley: Link >>> https://johnbrashear.tripod.com/bio/LangleySP.htm

Related Blog-Posts ---

"Leap-Year to be Even Longer w/ Added Leap-Second!" Mon., 2016 July 11.


"Slowing Earth Rotation Rate Necessitates June 'Leap Second'." Tue., 2015 Jan. 27.

Source: Glenn A. Walsh Reporting for SpaceWatchtower, a project of Friends of the Zeiss          

               Sunday, 2023 January 1.


                             Like This Post?  Please Share!

           More Astronomy & Science News - SpaceWatchtower Twitter Feed:
            Link >>> https://twitter.com/spacewatchtower

        Astronomy & Science Links: Link >>> http://buhlplanetarium.tripod.com/#sciencelinks

                Want to receive SpaceWatchtower blog posts in your in-box ?
                Send request to < spacewatchtower@planetarium.cc >.

gaw

Glenn A. Walsh, Informal Science Educator & Communicator                                                               (For more than 50 years! - Since Monday Morning, 1972 June 12):
Link >>> http://buhlplanetarium2.tripod.com/weblog/spacewatchtower/gaw/
Electronic Mail: < gawalsh@planetarium.cc >
Project Director, Friends of the Zeiss: Link >>> http://buhlplanetarium.tripod.com/fotz/
SpaceWatchtower Editor / Author: Link >>> http://spacewatchtower.blogspot.com/
Formerly Astronomical Observatory Coordinator & Planetarium Lecturer, original Buhl Planetarium & Institute of Popular Science (a.k.a. Buhl Science Center), America's fifth major planetarium and Pittsburgh's science & technology museum from 1939 to 1991.
Formerly Trustee, Andrew Carnegie Free Library and Music Hall, Pittsburgh suburb of Carnegie, Pennsylvania, the fourth of only five libraries where both construction and endowment funded by famous industrialist & philanthropist Andrew Carnegie.
Author of History Web Sites on the Internet --
* Buhl Planetarium, Pittsburgh: Link >>>  http://www.planetarium.cc  Buhl Observatory: Link >>>  http://spacewatchtower.blogspot.com/2016/11/75th-anniversary-americas-5th-public.html
* Adler Planetarium, Chicago: Link >>> http://adlerplanetarium.tripod.com
* Astronomer, Educator, Optician John A. Brashear: Link >>> http://johnbrashear.tripod.com
* Andrew Carnegie & Carnegie Libraries: Link >>> http://www.andrewcarnegie.cc

* Other Walsh-Authored Blog & Web-Sites: Link >>> https://buhlplanetarium.tripod.com/gawweb.html

Monday, December 19, 2022

Winter Begins at Solstice Wed.; Ursid Meteors Peak Thur.

http://buhlplanetarium.tripod.com/pix/graphics/solsticeimage008.png

This diagram shows the position of the Earth, in relation to the Sun, at the time of the Winter Solstice, as well as the other solstice and equinoxes of the year, in Earth's Northern Hemisphere.
[Graphic Source: ©1999, Eric G. Canali, former Floor Operations Manager of the original Buhl Planetarium & Institute of Popular Science (a.k.a. Buhl Science Center ), America's fifth major planetarium and Pittsburgh's science & technology museum from 1939 to 1991, and Founder of the South Hills Backyard Astronomers amateur astronomy club; permission granted for only non-profit use with credit to author.]

By Glenn A. Walsh

Reporting for SpaceWatchtower

The season of Winter, in the Northern Hemisphere of Earth, begins at the moment of the Winter / December Solstice, Wednesday Afternoon, 2022 December 21 at 4:48 p.m. Eastern Standard Time (EST) / 21:48 Coordinated Universal Time (UTC). This moment also marks the astronomical beginning of the Summer season in the Southern Hemisphere.

In Meteorology (Weather Science), the convention is to start a season on the first day of a calendar month. So, Meteorological Winter runs from 2022 December 1 to 2023 February 28.

This year's Winter Solstice marks the 54th anniversary of the launch of Apollo 8, the first human mission to the Moon. Apollo 8 astronauts Frank Borman, James Lovell, and William Anders launched from Cape Canaveral, Florida on 1968 December 21 at 7:51 a.m. EST / 12:51 UTC, entered lunar orbit early on the morning of Christmas Eve, orbited the Moon ten times, and returned to Earth on 1968 December 27.

Today marks the 50th anniversary (1972 December 19) of the return to Earth of the last human mission to the Moon, Apollo 17. Apollo missions 18, 19, and 20 had been cancelled, primarily due to budget cuts. Artemis I, NASA's first test mission for returning humans to the Moon after 50 years, landed in the Pacific Ocean a week ago, on 2022 December 11.

Almost exactly 24 hours after the Winter Solstice will mark the peak time for the annual Ursid Meteor Shower. This meteor shower peaks Thursday Afternoon, 2022 December 22 at 5:00 p.m. EST / 22:00 UTC (of course, meteor showers can only be viewed between local sunset and local sunrise, best viewed between local Midnight and local dawn when Earth is rotating into the meteor shower).

                                                              Winter Solstice

In etymology, the word solstice comes from the Latin terms sol (Sun) and sistere (to stand-still). In ancient times, astronomers / astrologers / priests recognized that one day of the year when the Sun would appear to reach its lowest point in the sky for the entire year. The motion of the Sun's apparent path in the sky (what is known astronomically today as the Sun's Declination) would cease on this day, and the Sun would appear to stand-still, before reversing direction.

With our Gregorian Calendar, this usually occurs on, or very close to, December 21. In ancient times, when people used the Julian Calendar, the Winter Solstice was on, or very close to, December 25, what we now know as Christmas Day. Mid-Winter festivals, at the time of the Winter Solstice, were common in ancient times. Instead of competing with these traditions, the early Roman Catholic Church Christianized the Winter festivals by observing the birth of Jesus Christ on December 25 (the actual birth date of Jesus was probably in late Summer or early Autumn).

Today, we know that, while the Sun does have motions (the Sun rotates on its own axis about once every 27 Earth days; our Solar System revolves around the center of the Milky Way Galaxy once every 225 million-to-250 million Earth years), it is actually the motion of the Earth, tilted on its axis (Mean Obliquity) currently ~23.43631 degrees / 23 degrees, 26 minutes, 10.7 seconds (at the North Latitude this is known as the Tropic of Cancer or Northern Tropic, while at the South Latitude this is located at the Tropic of Capricorn or Southern Tropic) from the plane of our Solar System while revolving around the Sun, that causes the Earth's seasons.

Hence, as the Earth arrives at the point in its orbit around the Sun, where the south polar axis is most directly inclined toward the Sun (thus, the Sun appears at its lowest point for the year in the Northern Hemisphere sky) around December 21, this marks the Winter Solstice in the Northern Hemisphere (and the Summer Solstice in the Southern Hemisphere).

Alternately around June 21, the Summer Solstice marks the beginning of Summer in the Northern Hemisphere (and this date also marks the Winter Solstice, which is the beginning of Winter in the Southern Hemisphere) as the Earth reaches the point in its orbit where the north polar axis is most directly inclined toward the Sun.

The day of the December Solstice is the only time of the year when the Sun reaches the point of Local Solar Noon at the South Pole. Conversely, it is also the only time of the year when Local Solar Midnight occurs at the North Pole. And, of course, it is the reverse during the June Solstice: the only time the Sun reaches the point of Local Solar Noon at the North Pole and the only time when Local Solar Midnight occurs at the South Pole.

Although the Winter months in the Northern Hemisphere are known for the year's coldest weather, the Earth is actually at the point in its orbit closest to the Sun (astronomically known as the point of Perihelion) on or very near January 2. The Earth is farthest from the Sun, each year shortly after the Northern Hemisphere's Summer Solstice, on or very near July 5 (the point of Aphelion). Over a half-year's time between Earth Perihelion and Earth Aphelion, the difference in distance between the Sun and Earth varies by about 3.2 million statute miles / 5.1499008 million kilometers.

This year, Earth Perihelion will occur on Wednesday Morning, 2023 January 4 at 11:17 a.m. EST / 16:17 UTC. At that moment, Earth will be the closest to the Sun for the whole year: 91,403,034 statute miles / 147.10 million kilometers. This year's Earth Aphelion: Thursday Afternoon, 2023 July 6 at 4:06 p.m. EST / 21:06 UTC - 94,506,364 statute miles / 1.5209 million kilometers.

Solar radiation, and hence heat from the Sun, to warm an Earth hemisphere depends on the length of daylight and the angle of the Sun above the horizon. Earth receives about 7 per-cent more solar radiation from the Sun during the time of Earth Perihelion in January, than at the time of Earth Aphelion in July. However, the tilt of the planet's axis toward the Sun determines the additional and more direct solar radiation received by a planet's northern or southern hemisphere, and hence, the warmer season of the respective hemisphere.

The Earth's Perihelion in January, and Aphelion in July, are due to the elliptical nature of the Earth's orbit around the Sun. Perihelion and Aphelion would not occur if the Earth's orbit was a true circle.

Since the Earth is closest to the Sun near the beginning of the Northern Hemisphere's Winter Season, the Earth, then, moves faster in its orbit around the Sun than it moves in July, making the Northern Hemisphere's Winter a shorter season than Summer. Winter will last for only 89 days, while this past-Summer lasted nearly 93 days. This is one of the observed consequences of Johannes Kepler's Laws of Planetary Motion, which he published at the beginning of the 17th century.

The day of the Winter Solstice is known as the “shortest day of the year” and the “longest night of the year” as the Sun shines on the Northern Hemisphere for the shortest length of time for the entire year, on this day. For this reason, Homeless Persons' Memorial Day is commemorated on December 21.

Since the Summer Solstice in June, the number of daylight hours have slowly diminished each day, with the night-time hours progressively increasing each day. This has benefited astronomers (to view planets, stars, and other celestial phenomena), amateur / ham radio operators (to communicate with other ham operators around the world), and long-distance (DX) radio enthusiasts (to receive AM / medium-wave and short-wave radio stations from around the country or around the world), who need the lack of solar radiation to ply their respective craft. Once we reach the Winter Solstice, the number of daylight hours will, now, slowly increase each day, with the night-time hours declining each day--until, once again, this reverses on the Summer Solstice.

Interestingly, the climate of a locale in the Southern Hemisphere is, on average, slightly milder than a location at the same latitude in the Northern Hemisphere, because the Southern Hemisphere has significantly more ocean water and much less land. Water warms-up and cools-down more slowly than does land. The only exception is the Antarctic Continent, which is colder than the Northern Hemisphere's Arctic region, possibly because most of the Arctic region is covered with water (although, often frozen water on the surface, but liquid water beneath the ice) while Antarctica is mostly a land mass.

On the Winter Solstice, the Sun appears (from Earth's perspective) to be in the constellation Sagittarius—that is, if you could view the stars behind the Sun on the Winter Solstice, you would see the stars of Sagittarius. Previously, just a few days earlier, the Sun had appeared to be in the constellation Ophiuchus. The change, when the Sun appeared to move from Sagittarius to Ophiuchus, occurred on December 17.

However, a couple thousand years ago, the Sun would have appeared to be in the constellation Capricornus during the Winter Solstice. And, about 150 years from now, the Sun will appear to be in the constellation Ophiuchus during the Winter Solstice. The names Tropic of Cancer and Tropic of Capricorn were coined in the last centuries B.C., when the Sun would appear in the Constellation Cancer the Crab on the June Solstice and in the Constellation Capricornus the Horned Goat on the December Solstice.

This apparent change is known as Precession of the Equinoxes or Axial Precession. This is a slow “wobble” of the Earth's axis, which causes the background stars or constellations that the Sun appears in to change over an approximately 25,771.5 year-cycle. This cycle runs through 12 traditional constellations of the zodiac, plus the constellation Ophiuchus, comprising the constellations along the ecliptic.

Precession also causes the North Star to change over the approximately 25,771.5 year-cycle. Today, Polaris is known as the North Star, which has been used for ages by navigators. However, at the time Egypt constructed the Great Pyramid, architects used Thuban, the North Star at that time, to align the pyramid. And, about 12,000 years from today, Vega will be the North Star.

Although for the year, December 21, for Earth's Northern Hemisphere, has the fewest number of daylight hours and the most night-time hours, it may be surprising to some that this date does not have the latest sunrise time nor the earliest sunset time for the year. This is also true for the June 21 solstice in the Southern Hemisphere.

Depending on a location's latitude, the latest sunrise time actually occurs a few days after the respective solstice, while the earliest sunset time occurs a few days before the day of the solstice. These time differences are due to, what scientists call, the Equation of Time (the Equation of Time is graphically displayed on most world globes as a figure “8”, known as the Analemma).

The U.S. Naval Observatory in Washington defines the Equation of Time: "the Equation of Time is the difference apparent solar time minus mean solar time". Apparent solar time, which is somewhat variable, directly tracks the motion of the Sun and can be measured using a sundial. Mean solar time measures solar motion if the Sun's motion was uniform; it is measured by an accurate clock which does not vary in time measurement. 

The Sun's motion does vary throughout the year. Hence, the latest sunrise time and the earliest sunset time do not occur on the actual day of the solstice.

                                               Ursid Meteor Shower

Almost 24 hours after the Winter Solstice comes the peak of the annual Ursid Meteor Shower, which actually begins on December 17 and usually lasts about a week ending December 24, 25, or 26. The Ursids seem to comprise a narrow stream of debris originating from Comet Tuttle. Hence, it is difficult to see Ursid meteors outside of a 12-hour window before and after the peak, where possibly 12 meteors per-hour could be seen, under ideal conditions.

The Ursid Meteor Shower is so-named because most meteors appear to radiate from a point near the Star Beta Ursae Minoris (apparent meteor shower radiant) in the Constellation Ursa Minor (better known as the asterism the “Little Dipper”), which is the brightest star in the bowl of the Little Dipper. Some people call these meteors “Ursids,” in an attempt to emphasize that their apparent radiant is Ursa Minor, not Ursa Major (the asterism the “Big Dipper”).

However, you should not, necessarily, be looking only at the Little Dipper when looking for meteors in this shower. Meteors can appear in any part of the sky at any time (although a meteor's tail may tend to point back toward the radiant).

Of course meteor showers, like all celestial observations, are weather-permitting. If there are more than a few clouds in the sky, meteors will be much more difficult to find. Clear skies are not always available in the skies of late Autumn and early Winter. And, it is always best to get away from city lights, for the opportunity to see the smaller, dimmer meteors. A bright Moon in the sky will also make it more difficult to view the smaller, dimmer meteors. As always, the best time to view any meteor shower is between local midnight and local dawn, when the Earth is actually rotating into the stream of meteoric debris.

Binoculars and telescopes are not very useful for finding meteors. Meteors streak across the sky in a very short period of time, far too short to aim binoculars or a telescope. So, the best way to view a meteor shower is to lie on a blanket or beach towel on the ground, or use a reclining a chair, outdoors in an area with a good view of the entire sky (with few obstructions such as buildings, trees, or hills), and keep scanning the entire sky.

So, if you go out to see the Ursid Meteor Shower, start looking for meteors around local midnight, or perhaps a little later. Make sure you have a good site where you can see most of the sky, and that sky is relatively clear. Be sure to dress properly for the early morning temperatures, now that we are at the very beginning of Winter.

And, you want to go out ahead of time, before you actually start looking for meteors, to get your eyes accustomed to the dark sky. Dark-adapting your eyes for meteor-watching could take up to a half-hour.

Internet Links to Additional Information ---  

Winter Solstice:
Link 1 >>> http://scienceworld.wolfram.com/astronomy/WinterSolstice.html
Link 2 >>> http://en.wikipedia.org/wiki/Winter
Solstice: Link >>> http://en.wikipedia.org/wiki/Solstice

Popular Winter Planetarium Sky Shows Shown at Pittsburgh's original Buhl Planetarium and Institute of Popular Science (1939 to 1991), including full scripts of each show:
The Star of Bethlehem >>> http://buhlplanetarium3.tripod.com/skyshow/bethlehem/
The Stars of Winter >>> http://buhlplanetarium3.tripod.com/skyshow/winter/

 Calendar Formats ---
       Gregorian Calendar: Link >>> http://en.wikipedia.org/wiki/Gregorian_calendar
       Julian Calendar: Link >>> http://en.wikipedia.org/wiki/Julian_calendar

Ursid Meteor Shower: Link >>> http://en.wikipedia.org/wiki/UrsidsA

 Homeless Persons' Memorial Day:
Link >>> http://nationalhomeless.org/about-us/projects/memorial-day/

Related Blog-Posts ---

"LIVE-STREAM: NASA Artemis Returns Sun., 50 Years After Last Apollo Moon Flight." Fri., 2022 Dec. 9.


"Live-Stream Web-Cast: NASA Artemis I to Orbit Moon - Launch Wed. 1:04 a.m."

Tue., 2022 Nov. 15.

Link >>> http://spacewatchtower.blogspot.com/2022/11/live-stream-web-cast-nasa-artemis-i-to.html 


American Lunar Society Founder on 50th Anniversary: 1st Humans Orbit Moon."

Mon., 2018 Dec. 24.

Source: Glenn A. Walsh Reporting for SpaceWatchtower, a project of Friends of the Zeiss          

               Monday, 2022 December 19.


                             Like This Post?  Please Share!

           More Astronomy & Science News - SpaceWatchtower Twitter Feed:
            Link >>> https://twitter.com/spacewatchtower

        Astronomy & Science Links: Link >>> http://buhlplanetarium.tripod.com/#sciencelinks

                Want to receive SpaceWatchtower blog posts in your in-box ?
                Send request to < spacewatchtower@planetarium.cc >.

gaw

Glenn A. Walsh, Informal Science Educator & Communicator                                                               (For more than 50 years! - Since Monday Morning, 1972 June 12):
Link >>> http://buhlplanetarium2.tripod.com/weblog/spacewatchtower/gaw/
Electronic Mail: < gawalsh@planetarium.cc >
Project Director, Friends of the Zeiss: Link >>> http://buhlplanetarium.tripod.com/fotz/
SpaceWatchtower Editor / Author: Link >>> http://spacewatchtower.blogspot.com/
Formerly Astronomical Observatory Coordinator & Planetarium Lecturer, original Buhl Planetarium & Institute of Popular Science (a.k.a. Buhl Science Center), America's fifth major planetarium and Pittsburgh's science & technology museum from 1939 to 1991.
Formerly Trustee, Andrew Carnegie Free Library and Music Hall, Pittsburgh suburb of Carnegie, Pennsylvania, the fourth of only five libraries where both construction and endowment funded by famous industrialist & philanthropist Andrew Carnegie.
Author of History Web Sites on the Internet --
* Buhl Planetarium, Pittsburgh: Link >>>  http://www.planetarium.cc  Buhl Observatory: Link >>>  http://spacewatchtower.blogspot.com/2016/11/75th-anniversary-americas-5th-public.html
* Adler Planetarium, Chicago: Link >>> http://adlerplanetarium.tripod.com
* Astronomer, Educator, Optician John A. Brashear: Link >>> http://johnbrashear.tripod.com
* Andrew Carnegie & Carnegie Libraries: Link >>> http://www.andrewcarnegie.cc

* Other Walsh-Authored Blog & Web-Sites: Link >>> https://buhlplanetarium.tripod.com/gawweb.html

Friday, December 9, 2022

LIVE-STREAM: NASA Artemis Returns Sun., 50 Years After Last Apollo Moon Flight


NASA Astronaut Eugene Cernan salutes the American flag on the lunar surface, during the final mission of humans to the Moon 50 years ago, Apollo 17. With the successful return of NASA's Artemis I test mission on Sunday, this salute may be repeated on the Moon in the next few years. (Image Sources: NASA, Wikipedia.org, By Harrison Schmitt - https://www.hq.nasa.gov/alsj/a17/AS17-134-20378HR.jpg, Public Domain, https://commons.wikimedia.org/w/index.php?curid=113250319)

By Glenn A. Walsh

Reporting for SpaceWatchtower

Artemis I, NASA's test mission for a human return to the Moon, is scheduled to splash-down in the Pacific Ocean, south of San Diego, early Sunday afternoon (2022 December 11). This will come 50 years after the last Apollo mission that landed astronauts on the Moon.

Splash-down of Artemis I is currently expected at 12:39 p.m. Eastern Standard Time (EST) / 17:39 Coordinated Universal Time (UTC) on Sunday Afternoon, 2022 December 11. NASA-TV Live-Stream coverage will begin Sunday morning at 11:00 a.m. EST / 16:00 UTC.

Internet link to NASA-TV Live-Stream coverage of the event near the end of this blog-post.

Apollo 17

The return of Artemis I comes 50 years after the mission of Apollo 17, the last mission to take American astronauts to the Moon. Apollo 17 was launched from Cape Canaveral, Florida on 1972 December 7 at 12:33 a.m. EST / 5:33 UTC.

NASA astronauts Eugene Cernan (mission Commander) and Harrison Schmitt (Lunar Module Pilot) landed on the Moon, while Ronald Evans (Command Module Pilot) continued orbiting the Moon. The Apollo 17 Lunar Excursion Module (LEM), Challenger, landed on the Moon at 2:55 p.m. EST / 19:55 UTC on 1972 December 11.

The astronauts on the Moon performed three EVAs (Extra-Vehicular Activities – in this case, Moon-walks), including the use of the third Project Apollo LRV (Lunar Rover), popularly known as the Moon Buggy. Humans took off from the Moon, for the last time in the 20th century, at 5:54 p.m. EST / 22:54 UTC on 1972 December 14. Apollo 17 splashed-down in the Pacific Ocean at 2:25 p.m. EST / 19:25 UTC on 1972 December 19.

Under pressure, NASA re-assigned Harrison Schmitt to Apollo 17, to ensure a professional scientist would be sent to the Moon, before the end of Project Apollo's Moon missions; Apollo missions 18, 19, and 20 had been canceled, primarily due to budget cuts. Harrison Schmitt was the only professional geologist to land on the Moon.

The Apollo 17 mission broke several records for human spacecraft:

  • Longest crewed lunar landing mission: 12 days, 14 hours

  • Greatest distance from a spacecraft during any type of EVA: 4.7 statute miles / 7.6 kilometers

  • Longest total lunar surface EVA: 22 hours, 4 minutes

  • Largest lunar sample return: ~254 pounds / ~115 kilograms

  • Longest time in lunar orbit: 6 days, 4 hours

  • Most lunar orbits: 75

Artemis I

According to the NASA Artemis I blog:

At present, we are on track to have a fully successful mission with some bonus objectives that we’ve achieved along the way,” said Mike Sarafin, Artemis I mission manager. “On entry day, we will realize our priority one objective, which is to demonstrate the vehicle at lunar re-entry conditions, as well as our priority three objective, which is to retrieve the spacecraft.”

Although the launch of Artemis I was delayed several times until the successful launch early on the morning of 2022 November 16, the mission has proceeded without major incidents. Now, the successful return, testing a new spacecraft heat-shield, is the last major test for this test mission.

After evaluating current weather conditions at the proposed landing site in the Pacific Ocean (off of San Diego), NASA officials decided to move the landing site a little further south, from the primary landing site. This new site is near Guadalupe Island, 130 nautical miles / 241 kilometers off of the west coast of Mexico's Baja California Peninsula.

Currently, both the Orion crew module and the service module are traveling back to Earth, similar to the Apollo missions. And, as with the Apollo missions, the Artemis service module will separate from the crew module just before re-entry into Earth's atmosphere. The service module will, then, burn-up as it re-enters the atmosphere.

The Artemis I trajectory is specifically designed by NASA to ensure that any parts of the service module, which do not burn-up in the atmosphere, do not pose a hazard to people, property, or shipping-lanes. This is in sharp contrast to the recent re-entry of Chinese space boosters, used to launch segments of their new space station into orbit. These boosters fell, completely uncontrolled, back to Earth. Fortunately, these boosters seem to have fallen into the Indian Ocean.

The Orion crew module will use a “skip entry” technique to re-enter Earth's atmosphere. According to NASA, this technique “enables the spacecraft to accurately and consistently splash down at the selected landing site. Orion will dip into the upper part of Earth’s atmosphere and use that atmosphere, along with the lift of the capsule, to skip back out of the atmosphere, then reenter for final descent under parachutes and splash down. This technique will allow a safe re-entry for future Artemis missions regardless of when and where they return from the Moon.”

Initially, the Earth's atmosphere will slow the spacecraft to 325 miles-per-hour / 523 kilometers-per-hour. Then, the parachutes will slow Orion to a splash-down speed in about 10 minutes.

At about 5 miles / 8 kilometers above the Earth's surface, three small parachutes will deploy. After the three small parachutes pull the forward bay covers away, two drogue parachutes will slow and stabilize the crew capsule. At an altitude of 9,500 feet / 2,895.6 meters and at a spacecraft speed of 130 miles-per-hour / 209 kilometers-per-hour, three pilot parachutes will lift and deploy the main parachutes. Those 116-foot / 35-kilometer diameter parachutes, made of nylon broad-cloth, will slow the Orion spacecraft to a splash-down speed of about 20 miles-per-hour / 32 kilometers-per-hour.

According to NASA, “The parachute system includes 11 parachutes made of 36,000 square feet of canopy material. The canopy is attached to the top of the spacecraft with more than 13 miles of Kevlar lines that are deployed in series using cannon-like mortars and pyrotechnic thrusters and bolt cutters.”

Just before 7:00 p.m. EST last evening (2022 December 8) / 0:00 UTC on December 9, Artemis was traveling back to Earth at a speed of 1,415 miles-per-hour / 2,277 kilometers-per-hour. The spacecraft was 207,200 statute miles / 333,456 kilometers from Earth and 180,400 statute miles / 290,325 kilometers from the Moon. 

Internet link to NASA-TV Live-Stream coverage of the return of Artemis I:

Link >>> https://www.nasa.gov/nasalive

NASA Artemis Blog: Link >>> https://blogs.nasa.gov/artemis/

Internet Links to Additional Information ---

 Artemis I -

NASA: Link >>> https://www.nasa.gov/artemis-1

Wikipedia: Link >>> https://en.wikipedia.org/wiki/Artemis_1

Apollo 17 -

NASA: Link >>> https://www.nasa.gov/feature/apollo-17-at-50-a-historians-look-back-at-apollo-and-to-the-future-of-the-artemis-generation

 Wikipedia: Link >>> https://en.wikipedia.org/wiki/Apollo_17

Artemis Program: Link >>> https://en.wikipedia.org/wiki/Artemis_program

Project Apollo: Link >>> https://en.wikipedia.org/wiki/Apollo_program

Canceled Apollo Missions: Link >>> https://en.wikipedia.org/wiki/Canceled_Apollo_missions

Related Blog-Posts ---

"Live-Stream Web-Cast: NASA Artemis I to Orbit Moon - Launch Wed. 1:04 a.m."

Tue., 2022 Nov. 15.

Link >>> http://spacewatchtower.blogspot.com/2022/11/live-stream-web-cast-nasa-artemis-i-to.html 


"UPDATE: Live-Stream: NASA Artemis I to Orbit Moon - Launch Perhaps Nov. 16."

2022 Aug. 28. Update 10: 2022 Nov. 8.

"Moonshot Space Museum Opens in Pittsburgh." Thur. 2022 Oct. 20.


"Public Comments Due May 31: NASA Plans to Explore Moon & Mars." Mon., 2022 May 23.


"Roll-Out Thur.: NASA's New Moon Rocket / Fly Your Name Around Moon on Artemis I." Tue., 2022 March 15.

Link >>> https://spacewatchtower.blogspot.com/2022/03/roll-out-nasas-new-moon-rocket-thur-fly.html

Source: Glenn A. Walsh Reporting for SpaceWatchtower, a project of Friends of the Zeiss          

               Friday, 2022 December 9.


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gaw

Glenn A. Walsh, Informal Science Educator & Communicator                                                               (For more than 50 years! - Since Monday Morning, 1972 June 12):
Link >>> http://buhlplanetarium2.tripod.com/weblog/spacewatchtower/gaw/
Electronic Mail: < gawalsh@planetarium.cc >
Project Director, Friends of the Zeiss: Link >>> http://buhlplanetarium.tripod.com/fotz/
SpaceWatchtower Editor / Author: Link >>> http://spacewatchtower.blogspot.com/
Formerly Astronomical Observatory Coordinator & Planetarium Lecturer, original Buhl Planetarium & Institute of Popular Science (a.k.a. Buhl Science Center), America's fifth major planetarium and Pittsburgh's science & technology museum from 1939 to 1991.
Formerly Trustee, Andrew Carnegie Free Library and Music Hall, Pittsburgh suburb of Carnegie, Pennsylvania, the fourth of only five libraries where both construction and endowment funded by famous industrialist & philanthropist Andrew Carnegie.
Author of History Web Sites on the Internet --
* Buhl Planetarium, Pittsburgh: Link >>>  http://www.planetarium.cc  Buhl Observatory: Link >>>  http://spacewatchtower.blogspot.com/2016/11/75th-anniversary-americas-5th-public.html
* Adler Planetarium, Chicago: Link >>> http://adlerplanetarium.tripod.com
* Astronomer, Educator, Optician John A. Brashear: Link >>> http://johnbrashear.tripod.com
* Andrew Carnegie & Carnegie Libraries: Link >>> http://www.andrewcarnegie.cc

* Other Walsh-Authored Blog & Web-Sites: Link >>> https://buhlplanetarium.tripod.com/gawweb.html