Tuesday, February 13, 2024

Sun-Blocking Space Umbrella to Cut Global Warming?

 

                          Artist's conception of a Space Umbrella deployed in Outer Space.

          (Image Source: Asher Space Research Institute of the Technion-Israel Institute of Technology)

By Glenn A. Walsh

Reporting for SpaceWatchtower

Could a giant umbrella in Outer Space reduce solar radiation hitting the Earth, and hence, contribute to a reduction in Global Warming? A proposal for a giant Sun-blocking umbrella to be constructed in Outer Space has been proposed by an Israeli physics professor.

Professor Yoram Rozen of the Asher Space Research Institute of the Technion-Israel Institute of Technology is floating the possibility that such a parasol floating in Space between the Sun and the Earth could provide some protection from advancing Climate Change. He calculates that such a large Space Umbrella could reduce solar heating of the Earth by 1 or 2 per-cent. Although this would not end Global Warming, it could be one way to reduce the heat received from the Sun.

Last year, the U.S. White House specifically announced that it was open to plans to block sunlight from hitting the Earth. In 2021, philanthropist Bill Gates had proposed spreading millions of tons of chalk dust high in the atmosphere to block sunlight; thus far, nothing has come of this proposal.

The Space Umbrella would have to be about 9 million statute miles / 14.48 million kilometers from the Earth. Scientists claim that, once deployed, the Space Umbrella could reduce the Earth's temperature by 2.7 degrees Fahrenheit within the first two years.

The Space Umbrella would consist of light-weight solar sails on a solar-powered spacecraft. It would move through Space by opening and closing the shading layer.

Such a Space Umbrella would need to be approximately one million square miles in size, about the size of the nation of Argentina! That size could not be launched at one time from Earth; sections of the Space Umbrella would have to launch separately and assembled in Space.

An alternative would be to launch a series of smaller Space Umbrellas that may add-up to about the same size. Another alternative would be to have such a Space Umbrella tethered to an asteroid.

A previous suggestion would have been to deploy dust at a La Grange Point (a location in Outer Space where the gravity between the Sun and the Earth are roughly equal, hence allowing matter at the La Grange Point to remain in one spot), so the dust would block some sunlight from reaching the Earth.

The Space Umbrella would use La Grange Point Number 1 (L1). According to the Israeli team, that point would provide a constant shading over a large portion of our planet.

Professor Rozen is now seeking $10-to-$20 million to build a prototype of a smaller size, about 100 square-feet, for construction by 2027. So far, no cost has been estimated for creating and launching a one million square-mile Space Umbrella. But, costs could reach trillions of dollars.

Skeptics of the Space Umbrella plan, including Harvard University astrophysicist Avi Loeb, note that the cost of such a large Space Umbrella(s) would be exorbitant. He said that such a plan would require international collaboration and probably reallocation of funds from the military.

Skeptics also note that launching, assembling, and maintaining such a parasol in Outer Space would be extremely challenging, similar, but to a much greater scale, to the recent launch of the James Webb Space Telescope. There is also a question as to how well such a Space Umbrella could hold-up to the harsh conditions of Outer Space.

Further, a solar storm, meteor, or asteroid that damages the Space Umbrella could result in sudden and rapid warming on Earth, with possible disastrous effects and no ready way to repair such damage.

However, the non-profit Planetary Sunshade Foundation supports the Israeli proposal. They believe the project cost may not be as high as projected, as the costs of space travel continue declining.

Again, this plan, if implemented, would not be a 'silver bullet'. This would be just one way to reduce some heating of the Earth, while the nations of our planet make the hard choices needed for a more permanent solution.

Internet Links to Additional Information ---

Space Sun Shade: Link >>> https://en.wikipedia.org/wiki/Space_sunshade

La Grange Point: Link >>> https://en.wikipedia.org/wiki/Lagrange_point

Climate Change: Link >>> https://en.wikipedia.org/wiki/Climate_change

Global Warming Potential: Link >>> https://en.wikipedia.org/wiki/Global_warming_potential

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

               "Sun-Blocking Space Umbrella to Cut Global Warming?"

                  Tuesday, 2024 February 13.

            Artificial Intelligence not used in the writing of this article.

            © Copyright 2024 Glenn A. Walsh, All Rights Reserved

                             Like This Post? Please Share!

More Astronomy & Science News - SpaceWatchtower 'X' / 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

Saturday, January 27, 2024

Laser Observatory in Space to Expand Search for Gravity-Waves


 Artist's conception of the Laser Interferometer Space Antenna (LISA) to be launched by 2035.

(Image Sources: NASA / Jet Propulsion Laboratory, Wikipedia.org, By NASA - NASA, Public Domain, https://commons.wikimedia.org/w/index.php?curid=10372273)

By Glenn A. Walsh

Reporting for SpaceWatchtower

With the first detection of Gravitational-Waves coming from a ground-based observatory in 2015, now there is a plan to expand the search for Gravitational-Waves with an observatory in Outer Space. This past week, the European Space Agency (ESA) announced an ambitious plan to launch the Laser Interferometer Space Antenna (LISA) by 2035.

Gravitational-Waves, described as ripples in the fabric of Space-Time, have been very difficult to find since the search began more than two decades ago. Gravitational-Waves often are produced by the collision of large Black Holes.

Scientists believe that further study of Gravitational-Waves will help them learn more about the workings and history of our Universe. Learning more about the Black Holes and Supernovae that cause Gravitational-Waves may also help them learn more about the creation and evolution of the Galaxies these phenomena inhabit.

A space-based Laser observatory would allow researchers to detect Gravitational-Waves of much longer wavelengths than can be sensed on Earth. This would detect the collision of much larger Black Holes, which are millions of times the size of our Sun.

The Laser Interferometer Space Antenna would use three spacecraft firing Lasers at each other, over distances larger than the orbit of Earth's Moon: ranging up to 1.5 million statute miles / 2.5 million kilometers. The three spacecraft detectors will be arranged in Outer Space as an equilateral triangle.

The spacecraft will be placed in orbit of the Sun, at the same distance from the Sun as the Earth, but trailing the Earth by 20 degrees. Each spacecraft will be built as a Zero-Drag Satellite, to eliminate light pressure and the Solar Wind from affecting the detection results.

Officials at the European Space Agency project the LISA budget will cost 1.75 billion Euros / 1.5 billion British Pounds / $1.5 billion. Additional funds are expected to come from member states such as Germany, France, Italy, the UK, the Netherlands and Switzerland.

NASA, which had been part of the original LISA proposal as far back as 1997, will also be part of this project. NASA's contribution will include more advanced technologies including Lasers.

Currently, the Earth-based Laser Interferometer Gravitational-Wave Observatory (LIGO) consists of two Laser stations in Hanford, Washington and Livingston, Louisiana, the largest and most ambitious project ever funded by the U.S. National Science Foundation (NSF). Built and operated by the California Institute of Technology and Massachusetts Institute of Technology, the initial project ran from 2002 to 2010 when no Gravitational-Waves were found.

The Advanced LIGO Project began in 2008, with the enhanced detectors beginning operation in 2015. Two days after beginning operation, the first Gravitational-Wave was detected on 2015 September 14.

The detection of Gravitational-Waves confirmed a prediction of Albert Einstein's 1916 General Theory of Relativity. A new branch of observational Astronomy, Gravitational-Wave Astronomy obtains and studies data from highly-energetic sources of Gravitational-Waves such as Black Holes and Supernovae. Although predicted by Dr. Einstein, he had doubted whether Gravitational-Waves could ever actually be detected.

Three American physicists, who developed a Laser observatory which led to the detection of Gravitational-Waves, were awarded the 2017 Nobel Prize in Physics on Tuesday, 2017 October 3. Barry C. Barish and Kip S. Thorne of the California Institute of Technology and Rainer Weiss of the Massachusetts Institute of Technology were given the annual award "for decisive contributions to the LIGO detector and the observation of Gravitational-Waves."

Presently, Gravitational-Waves are detected in LIGO from the perturbations of Laser light as fired down 4-kilometer-long L-shaped tunnels. LISA will use the same principle, but over much larger distances in Outer Space.

Internet Links to Additional Information ---

Laser Interferometer Space Antenna (LISA):

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

Laser Interferometer Gravitational-Wave Observatory (LIGO):

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

Black Hole: Link >>> https://en.wikipedia.org/wiki/Black_hole

Supernova / Supernovae: Link >>> https://en.wikipedia.org/wiki/Supernova

Related Blog-Post ---

"Physics Nobel Prize Awarded to Developers of Laser Observatory." Sat., 2017 Oct. 7.

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

               "Laser Observatory in Space to Expand Search for Gravity-Waves."

                  Saturday, 2024 January 27.

            Artificial Intelligence not used in the writing of this article.

            © Copyright 2024 Glenn A. Walsh, All Rights Reserved

                             Like This Post? Please Share!

More Astronomy & Science News - SpaceWatchtower 'X' / 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

Thursday, January 4, 2024

Live-Stream - Early Mon. Launch: U.S. Robotic Return to Moon

                 

Observation windows looking into the Astrobotic Clean Room, from the Moonshot Space Museum, located on Pittsburgh's Lower North Side. In this photograph, two Astrobotic technicians are working on the Peregrine Moon Lander, scheduled to be launched to the Moon early Monday Morning, 2024 January 8. This photograph was taken on the day of dedication of the Moonshot Space Museum: Saturday, 2022 October 15.

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

By Glenn A. Walsh

Reporting for SpaceWatchtower

America's return to the Moon, with a robotic lander and rover, is now planned for launch in the early hours of January 8. This NASA Commercial Lunar Payload Services (CLPS) project, the Peregrine Lander carrying 21 payloads, was built by Astrobotic Technology, Inc. of Pittsburgh and the Iris Rover was produced by Carnegie Mellon University.

Over the years, the United States has had several fly-by and orbital missions to the Moon, since the last Apollo mission, Apollo 17, left the Moon on 1972 December 14. Peregrine Mission One will be the first American lander and rover since the days of Apollo.

Peregrine Mission One will be launched atop a United Launch Alliance (ULA) Vulcan Centaur rocket from the Cape Canaveral Space Force Station in Florida [Space Launch Complex 41 (SLC-41)]. This is the first flight of this particular rocket, a successor to ULA's Atlas V and Delta IV launch vehicles.

Getting such a new rocket ready for launch, and passing NASA requirements, meant that the original 2023 May 4 launch date slipped until Christmas Eve of last year. Then, “routine” issues regarding ground equipment resulted in United Launch Alliance (ULA) Chief Executive Officer Tory Bruno, in a Social Media Post, announcing that the launch would be again delayed to no earlier than January 8.

Launch of the Peregrine mission is now scheduled for early on Monday Morning 2024 January 8: 2:18:38 a.m. Eastern Standard Time (EST) / 7:18:38 Coordinated Universal Time (UTC) (45-minute lainch window).

While it had been scheduled on Traditional Christmas Eve, the new launch date is one day after the celebration of Orthodox Christmas. It was on Traditional Christmas Eve, this time in 1968, when humans first entered orbit around another planetary body, the Earth's Moon, during the historic mission of Apollo 8.

The Peregrine Mission One launch window continues for four days, if a launch cannot occur on January 8. Provided the launch does occur one of these four days, landing on the Moon is expected on Friday, 2024 February 23.

Internet Link to Live-Stream Web-Cast of Astrobotic Launch Near End of Blog-Post.

About an hour or so after launch, the Peregrine Lander and Iris Rover will separate from the launch vehicle and enter a Trans-lunar Injection for the beginning of the trip to the Moon. After entering a medium orbit around the Moon, landing the spacecraft will wait until early morning at the landing site: Sinus Viscositatis ('Bay of Stickiness') located at 35.25 degrees North and 40.99 degrees west on the Moon.

By landing early in the morning on the Moon, this will give the mission eight-to-ten days of operation while the Sun is shining. Once nightfall descends on the spacecraft, operations will stop and wait for the next sunrise.

However, Astrobotic Founder and Chief Executive Officer John Thornton warns that with the cold of a lunar night, it is not known how that may affect the equipment; he said that India's Chandrayaan-3 Lander did not resume operation after lunar night. According to Mr. Thornton, the Moon's surface temperature varies from about +212 to +248 degrees Fahrenheit / +100 to +120 degrees Celsius in the daytime “down to liquid nitrogen cold” at night; a lot of things can break at such low nighttime temperatures.

Another NASA CLPS mission, the launch of Intuitive Machines Nova-C Lander (IM-1 Mission) on a SpaceX Falcon 9 rocket, has also been delayed and is now scheduled to launch after the Peregrine Lander, in mid-FebruaryBut if the current IM-1 Mission schedule holds, it may actually land on the Moon within days (perhaps as early as February 22) of the Peregrine Lander.

The Iris Rover is a collaboration between the students, professors, and staff from Carnegie Mellon University and Astrobotic in the development of robotics technology for Outer Space. The rover name Iris is Siri spelled backwards, in honor of Carnegie Mellon University Lead Systems Engineer Siri Maley. The Iris robotic mission will be the smallest, first American, first university-built, and first student-built rover on the Earth's Moon.

Carnegie Mellon University is also providing another payload called MoonArk, which Astrobotic describes as a “collaborative space project”. This sort-of space museum “embodies the arts, humanities, sciences, and technologies in a set of intricately designed objects intended to spark wonderment and discovery for future generations.”

Among the 21 payloads on this mission are instruments from NASA research centers: Ames Research Center (Moffett Federal Airfield, Silicon Valley, California), Goddard Space Flight Center (Greenbelt, Maryland), and Johnson Space Center (Houston, Texas) ---

  • Laser Retroreflector Array (LRA) – GSFC

  • Linear Energy Transfer Spectrometer (LETS) – JSC

  • Near InfraRed Volatiles Spectrometer System (NIRVSS) – ARC

  • Neutron Spectrometer System (NSS) – ARC

  • Peregrine Ion-Trap Mass Spectrometer (PITMS) – GSFC/European Space Agency

Peregrine Mission One, part of NASA's Commercial Lunar Payload Services (CLPS) initiative, is scheduled to be the first United States commercial robotic lander launching to the Moon's surface, as part of the NASA Artemis Program to return astronauts to the Moon by the end of this decade.

Other payloads include a M-42 Radiation Detector from the German Aerospace Center, as well as scientific payloads from the United Kingdom, Mexico, and Hungary. And, scientists from the Seychelles are sending one Bit-coin.

Two American space companies, Celestis and Elysium Space, are sending the cremated remains and DNA of 70 people's loved ones on the spacecraft. The human remains will be interred in flight capsules, permanently encased in a lunar lander spacecraft. The cremated remains of a couple famous persons in the Peregrine Mission One include Star Trek creator Gene Roddenberry and science fiction writer Arthur C. Clarke.

The remains of another 265 persons will be represented on the rocket's upper stage, which will go into orbit of the Sun. These include three original Star Trek cast members [Nichelle Nichols (Lt. Nyota Uhura), DeForest Kelley (Dr. Leonard “Bones” McCoy), and James Doohan (Montgomery “Scotty” Scott)], as well as strands of hair from three American Presidents: George Washington, Dwight D. Eisenhower, and John F. Kennedy.

Japan's Lunar Dream Capsule, from the company Astroscale, is described as a “time capsule”. The time capsule includes messages from 80,000 children from around the world.

NASA invites all members of the general public, throughout the world, to attend the Peregrine launch virtually. According to NASA:

Members of the public can register to attend the launch virtually:

Link >>> https://www.eventbrite.com/e/nasas-commercial-lunar-payload-services-astrobotic-peregrine-1-launch-registration-525735457907?aff=webfeature

As a virtual guest, you have access to curated resources, schedule changes, and mission-specific information delivered straight to your in-box. Following each activity, virtual guests will receive a commemorative stamp for their virtual guest passport:

Link >>> https://nasa-external-ocomm.app.box.com/s/mhdv60p0g3xowte635a27peqibwgcezh

More information about NASA CLPS activities can be found on the CLPS Blog:

Link >>> https://blogs.nasa.gov/clps

A commercial spin-off from Carnegie Mellon University, Astrobotic opened a Moonshot Space Museum on Pittsburgh's Lower North Side on Saturday Morning, 2022 October 15. This new museum is located adjacent to Astrobotic's manufacturing facility. In addition to STEM (Science, Technology, Engineering, and Mathematics) education for young people, this museum allows the general public to watch Moon rovers being constructed.

Carnegie Mellon University originated in 1900 as the Carnegie Technical Schools. It was established to provide for a technical education by famous industrialist and philanthropist Andrew Carnegie.

Internet Link to Live-Stream Web-Cast of Astrobotic Launch ---

Link >>> https://www.nasa.gov/nasatv/

Internet Links to Additional Information ---

Peregrine Mission One ---

Link 1 >>> https://www.nasa.gov/missions/artemis/clps/astrobotic-peregrine-mission-one/

Link 2 >>> https://en.wikipedia.org/wiki/Peregrine_Mission_One

Astrobotic Technology ---

Astrobotic: Link >>> https://www.astrobotic.com/

Peregine Mission One Update: L nk >>> https://www.astrobotic.com/peregrine-mission-one-update/

Peregine Mission One Manifest: Link >>> https://www.astrobotic.com/lunar-delivery/manifest/

Carnegie Mellon Iris & MoonArk:

Link >>> https://www.cmu.edu/news/stories/archives/2023/october/cmus-iris-moonark-leave-pittsburgh-en-route-to-the-moon

Related Blog-Posts ---

"UPDATE: Launch Slips to Jan. for U.S. Robotic Return to Moon." 2023 Dec. 11 (Original Blog-Post: 2023 Dec. 7).


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

Moonshot Space Museum sponsored by Astrobotic Technology.

"CMU to Build 1st Univ.-Based Space Mission Control." Mon., 2022 April 18.


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

Mon., 2018 Dec. 24.

"Library to be Established on the Moon !" Mon., 2018 May 2.

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

               "Live-Stream - Early Mon. Launch: U.S. Robotic Return to Moon."

                  Thursday, 2024 January 4.

            Artificial Intelligence not used in the writing of this article.

            © Copyright 2024 Glenn A. Walsh, All Rights Reserved

                             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 18, 2023

Winter Begins at Solstice Thur. Night; Ursid Meteors Peak Friday

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 / 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, Thursday Evening, 2023 December 21 at 10:27 p.m. Eastern Standard Time (EST) / December 22, 3:27 Coordinated Universal Time (UTC). This moment also marks the astronomical beginning of the Summer season in the Southern Hemisphere.

Winter continues in Earth's Northern Hemisphere until Spring begins on the Vernal Equinox: Tuesday, 2024 March 19 at 11:07 p.m. Eastern Daylight Saving Time (EDT) / March 20 at 3:07 UTC. This also marks the beginning of Autumn / Fall 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 December 1 to February 28 or 29.

This year's Winter Solstice marks the 55th 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.

Tomorrow marks the 51st 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.

Almost exactly 24 hours after the Winter Solstice will mark the peak time for the annual Ursid Meteor Shower. This meteor shower peaks Friday Evening, 2023 December 22 at 11:00 p.m. EST / December 23, 4:00 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 of Nazareth was probably either in the Spring or around Harvest-time (late Summer / 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 23.43616 degrees / 23 degrees, 26 minutes, 10.1 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.

The dates of Earth Perihelion and Earth Aphelion are not fixed. Due to the Earth's Precession of the Equinoxes, these days shift forward approximately one day every 58 years. About 800 years ago, the Earth Perihelion was on the date of the Winter Solstice, around December 21; Earth Perihelion will be on the Vernal Equinox, the beginning of Spring around March 20, about 4,300 years from now. Earth's Axial Precession (often described as a "wobble" in the Earth's orientation, like a spinning top or a gyroscope) gradually changes the orientation of the Earth's Rotational Axis, which completes one rotational cycle once every 25,772 years.

This year, Earth Perihelion will occur on Tuesday Evening, 2024 January 2 at 7:38 p.m. EST / January 3, 0:38 UTC. At that moment, Earth will be the closest to the Sun for the whole year: 91,404,095 statute miles / 147,100,632 kilometers. This year's Earth Aphelion: Friday Morning, 2024 July 5 at 1:06 a.m. Eastern Daylight Saving Time (EDT) / 5:06 UTC - 94,510,539 statute miles / 152,099,968.88 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 (best results: look in darkest parts of 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 ---

"'The Night the Stars Fell' 190 Years Ago: Beginning of Citizen Science."

Mon., 2023 November 13.


"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     

               "Winter Begins at Solstice Thur. Night; Ursid Meteors Peak Friday."

                  Monday, 2023 December 18.

            Artificial Intelligence not used in the writing of this article.

            © Copyright 2023 Glenn A. Walsh, All Rights Reserved

                             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

Saturday, December 9, 2023

Halley's Comet Aphelion - Farthest from Sun


Halley's Comet, as seen from Easter Island on 1986 March 8; photographer: W. Liller (International Halley Watch, Large Scale Phenomena Network).

(Image Sources: NASA, Wikipedia.org, By NASA/W. Liller - NSSDC&#039;s Photo Gallery (NASA):http://nssdc.gsfc.nasa.gov/photo_gallery/photogallery-comets.htmlhttp://nssdc.gsfc.nasa.gov/image/planetary/comet/lspn_comet_halley1.jpg, Public Domain, https://commons.wikimedia.org/w/index.php?curid=544352) 

By Glenn A. Walsh

Reporting for SpaceWatchtower

TODAY (Saturday, 2023 December 9) marks Aphelion for Comet Halley, the comet's farthest point in their orbit of the Sun. Halley's Comet's last Perihelion, their closest approaches to the Sun and Earth, came in 1986. Halley's Comet's next Perihelion will come in 2061.

1910 – Astronomer John Brashear shows Halley's Comet to the general public, using telescopes in Pittsburgh's Riverview Park, on the front lawn of the Allegheny Observatory.

1985 & 1986 – Pittsburgh's Buhl Science Center shows Halley's Comet to the general public, using telescopes in the original Buhl Planetarium Observatory, including the historic 10-inch Siderostat-type Refractor Telescope.

2023 December 9 – Halley's Comet reaches Aphelion.

2061 July 28 – Next Halley's Comet Perihelion.

Internet Links to Additional Information ---

Halley's Comet: Link >>> https://en.wikipedia.org/wiki/Halley's_Comet

StarDate - "Distant Comet": Link >>> https://stardate.org/radio/program/2023-12-09

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

               Saturday, 2023 December 9.


                             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