Monday, December 24, 2018

50th Anniversary: The Incredible Legacy of Apollo 8

The famous 'Earthrise' photograph from the NASA spacecraft Apollo 8, the first mission with human beings to travel to the Moon; this photograph helped to spark the Earth environmental movement of the 1970s. The crew entered lunar orbit 50 years ago on Christmas Eve, Tuesday, 1968 December 24. That evening, the astronauts held a live television broadcast, reading passages from the Book of Genesis in the Christian Bible and showing pictures of the Earth and Moon as seen from their spacecraft.
(Image Source: NASA)

Editor's Note: Precisely 50 years ago, from the time of the posting of this blog-post, NASA's Apollo 8 spacecraft became the first space mission with humans to go behind Earth's Moon, out of sight and out of touch with Earth, and enter lunar orbit: 4:59 a.m. Eastern Standard Time (EST) / 9:59 Coordinated Universal Time (UTC) on Tuesday, 1968 December 24, Christmas Eve. The following is a brief essay regarding the historical and scientific significance of the Apollo 8 mission. The author of this essay is Francis G. Graham, Professor Emeritus of Physics, Kent State University, and Founder of the American Lunar Society. Earlier in his career, he was a Planetarium and Observatory Lecturer at the original Buhl Planetarium and Institute of Popular Science (a.k.a. Buhl Science Center), Pittsburgh's science and technology museum from 1939 to 1991.

                                  THE INCREDIBLE LEGACY OF APOLLO 8

By Francis G. Graham, Professor Emeritus of Physics, Kent State University
                        and Founder of the American Lunar Society
Reporting for SpaceWatchtower


December 21, 1968 was the shortest day of the year for areas of Planet Earth north of the equator. But it was the longest stretch of a day in history. As Carl Sagan pointed out, people in the 25th century, if there are any, will not remember the causes of the war in Afghanistan or the political machinations of the Trump administration. Instead, they will remember that in the late 1960’s there were the first expeditions of humans to the Moon and the space beyond Earth orbit.

It was on that day that Apollo 8, the first human expedition to the Moon, left the Earth. There was no landing, the flight was a flight around the Moon, in lunar orbit. The rocket that propelled it there was a great marvel, the 360-foot-tall Saturn V, using hydrocarbons and liquid oxygen as fuel. Of the entire 360-foot-tall rocket, only the 12-foot-tall Command Module capsule returns to Earth from the Moon. Consider that 29/30 of the length is discarded along the way, and an even larger amount of the mass. It is quite possible in the year 4200 some Thor Heyerdahl will try to prove that the Ancient Americans could have reached the Moon on such improbable chemical rockets.


           
The launch of Apollo 8 occurred Saturday, 1968 December 21 at 7:51:00 EST / 12:51:00 UTC, on the day of the Winter Solstice in the Northern Hemisphere (which occurred at 1:59 p.m. EST / 18:59 UTC). (Image Source: NASA)

The astronauts on Apollo 8 are legends. Colonel Frank Borman of the U.S. Air Force, part of the Gemini 7 mission three years prior, was the Command Pilot; Captain James A. Lovell, a Naval Pilot, part of the 1966 Gemini 12 mission, was the Command Module Pilot, and would return to the region of the Moon again in Apollo 13. Lovell was the only man who could claim to have visited the Moon twice, with the exception of Baron von Munchausen, who notably also claimed that distinction, but with far less veracity. Finally, there was Major William Anders, an Air Force pilot, who was designated the Lunar Module Pilot, but in Apollo 8 he had no Lunar Module to pilot.

Apollo 8 was not initially supposed to be a lunar mission, but an Earth orbital one. Instead, Apollo 9 was the developmental checkout mission in Earth orbit that was to have been originally Apollo 8. However, it is not generally known that there were geopolitical reasons why Apollo 8 was designated as a lunar orbit mission in December, 1968. In Kazakhstan, the Soviet Union had a lunar orbit mission or a circumlunar mission on the launch pad being prepared for launch. A Soyuz craft was on top of a Proton booster, and could then, or even now, perform a lunar circumlunar mission. Modified Soyuz craft were previously sent on unmanned circumlunar missions, called the Zond series, one even carried animals and returned them safely to Earth. A painting of a Soyuz craft in the National Air and Space Museum shows a rear toroidal fuel tank, which would have been used on the circumlunar mission.

Problems with the manned Zond circumlunar mission kept it on the ground in December, 1968, and then Apollo 8 became the first lunar mission. The manned Zond was then canceled.
 
The Apollo 8 mission accomplished its objectives: engineering tests of the Apollo-Saturn V system, lunar photography and panoramic camera imaging from lunar orbit. Most importantly was the photography of the Earth from lunar orbit, which truly transformed the perspective of many people. After all, until Apollo 8, and starting with Magellan’s expedition in 1522, there had been only circumnavigation of the Earth, albeit successively faster. Apollo 8 was topologically different, it was an orbit of the Moon. With Apollo 8, we saw the Earth whole and distant, rising above the lunar surface as Apollo 8 orbited.

On Christmas night, with the Moon and Earth in the television camera, passages from the Bible were read by the astronauts. There were, to be sure, some who objected on separation of state issues, as Apollo was a government program. But most Americans were deeply touched by the reading and the view from space.

But when one considers the U.S. Constitution, one wonders why there should have been an Apollo at all. The powers of the government in the Constitution, e.g common defense, courts, etc. do not include space travel. There was no military utility in the Moon. Normally in America new transportation technology was pioneered by private enterprise; in the pre-Apollo realistic George Pal movie Destination Moon and in the prophetic Fritz Lang silent film Frau im Mond this was the case. But in Apollo, we saw a government financing the trips to the Moon; ironic since in the opposing Communist system the government also financed space travel. Now we are seeing a shift toward private financing of space travel 50 years later, although, even in the time of the Apollos, communications satellite technology was privately financed to a large degree.

Apollo 8 was truly revolutionary, and the further efforts of 1969-72 built upon it. We can only wonder when a return to the Moon will occur, and who will do it.

Internet Links to Additional Information ---

Apollo 8 -
Link 1 >>> https://www.nasa.gov/mission_pages/apollo/missions/apollo8.html
Link 2 >>> https://www.nasa.gov/topics/history/features/apollo_8.html
Link 3 >>> https://solarsystem.nasa.gov/missions/apollo-8/in-depth/
Link 4 >>> https://en.wikipedia.org/wiki/Apollo_8

Related Blog Posts ---

"45th Anniversary: Apollo 8 Orbits the Moon Christmas Eve." 2013 Dec. 24.

Link >>> http://spacewatchtower.blogspot.com/2013/12/45th-anniversary-apollo-8-orbits-moon.html

 

"45 Years Ago: Man Lands on the Moon !" 2014 July 20.

Link >>> https://spacewatchtower.blogspot.com/2014/07/45-years-ago-man-lands-on-moon.html

 

Source: Francis G. Graham, Professor Emeritus of Physics, Kent State University and Founder of the American Lunar Society. Earlier in his career, Planetarium and Observatory Lecturer at the original Buhl Planetarium and Institute of Popular Science (a.k.a. Buhl Science Center), Pittsburgh's science and technology museum from 1939 to 1991.
              Monday, 2018 December 24.

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gaw

Glenn A. Walsh --- < http://buhlplanetarium2.tripod.com/weblog/spacewatchtower/gaw/ >
Electronic Mail: < gawalsh@planetarium.cc >
Project Director, Friends of the Zeiss: < http://buhlplanetarium.tripod.com/fotz/ >
SpaceWatchtower Editor / Author: < http://spacewatchtower.blogspot.com/ >
Formerly Astronomical Observatory Coordinator & Planetarium Lecturer, original Buhl Planetarium & Institute of Popular Science (a.k.a. Buhl Science Center), Pittsburgh's science & technology museum from 1939 to 1991. Formerly Trustee of the Andrew Carnegie Free Library and Music Hall, Pittsburgh suburb of Carnegie, Pennsylvania.
Author of History Web Sites on the Internet --
* Buhl Planetarium, Pittsburgh:
  < http://www.planetarium.cc >
* Adler Planetarium, Chicago:
  < http://adlerplanetarium.tripod.com >
* Astronomer, Educator, Optician John A. Brashear:
  < http://johnbrashear.tripod.com >
* Andrew Carnegie & Carnegie Libraries:
  < http://www.andrewcarnegie.cc >

Thursday, December 20, 2018

Winter Begins Friday; Full Moon & Ursid Meteors Peak Saturday

   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 Pittsburgh's original Buhl Planetarium and Institute of Popular Science 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, Friday Afternoon, 2018 December 21 at 5:23 p.m. Eastern Standard Time (EST) / 22:23 Coordinated Universal Time (UTC). This moment also marks the astronomical beginning of the Summer season in the Southern Hemisphere.

Almost 24 hours later, Saturday Afternoon will mark the peak time for the annual Ursid Meteor Shower; of course dark skies are needed to actually see meteors. This meteor shower peaks Saturday Afternoon, 2018 December 22 at 4:00 p.m. EST / 21:00 UTC.

Plus, this year the December Full Moon occurs on Saturday just after Noon in the Eastern Standard Time Zone of the Northern Hemisphere: Saturday Afternoon, 2018 December 22, 12:49 p.m. EST / 17:49 UTC. AND, it was 50 years ago on Friday (1968 December 21 at 7:51:00 a.m. EST / 12:51:00 UTC) that humans began their first voyage to the Moon, when Apollo 8 was launched for a successful mission orbiting the Moon

                                               Winter Solstice 2018

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 September).

Today, we know that, while the Sun does have motions, it is actually the motion of the Earth, tilted on its axis 23.44 degrees 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).

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. 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 is 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.

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, 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.

                                              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. 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.

                                            December Full Moon

In our sky, the Moon lines-up opposite the Sun during the Full Moon phase, both appearing to travel along the Ecliptic, the apparent path on the celestial sphere where we find the major planets of our Solar System as well as the Sun and the Moon. This is due to the fact that all of these major bodies travel within a particular plane of the Solar System.

When we view the Moon in our sky, it appears to do the opposite of what the Sun does. When the Sun is high in the sky near the Summer Solstice in June, the Moon is low in the sky. This is because at the Summer Solstice, the North Pole is tilted the maximum extent (23.44 degrees) toward the Sun and away from the Moon.

When the Sun is low in the sky near the time of the Winter Solstice in December (when the North Pole is tilted the maximum extent, 23.44 degrees, away from the Sun and toward the Moon), the Northern Hemisphere receives the lowest number of sunlit hours for the year. Then, the Moon is high in the sky and a Full Moon at this time is bright and appears in the sky for the longest length of time for the year.

The December Full Moon in the Northern Hemisphere of Earth was known to Native Americans as the Cold Moon or the Long Nights Moon, and sometimes also referred to as the Moon Before Yule. Other names given to the December Full Moon have been reported by the Farmers' Almanac (Oak Moon) and The American Boy's Book of Signs, Signals and Symbols published in 1918 for use by the Boy Scouts (Wolves Moon and Big Moon).

Of course Cold Moon refers to the cold temperatures that begin with the start of the Winter season this month. And, the Moon Before Yule was used by the Christian settlers to refer to the Full Moon before Christmas Day (Yule being an early religious festival observed by Germanic peoples, later absorbed and equated with Christmas); of course, this name would not be used during years when the December Full Moon is after Christmas Day.

With the longest night of the year occurring near the Winter Solstice, this justifies the term Long Nights Moon, as the Full Moon is visible all-night long, rising approximately at sunset and setting approximately at sunrise. And, this month's Moon is high in the Northern Hemisphere sky, as this is the time of the year that the Sun is the lowest in the sky; traveling high in the sky also means the Moon stays in the sky longer.

A couple centuries ago, when night artificial lighting had little effect and the December Full Moon brightened a snowy field, one might see how some people may refer to this as a Big Moon.

In the Southern Hemisphere, the December Full Moon is known as the Strawberry Moon, Honey Moon, and Rose Moon.

Special Thanks: Eric G. Canali, former Floor Operations Manager of Pittsburgh's original Buhl Planetarium and Institute of Popular Science and Founder of the South Hills Backyard Astronomers amateur astronomy club.

Internet Links to Additional Information ---

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

More on a 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/

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

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

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

More on the Full Moon: Link >>> http://en.wikipedia.org/wiki/Full_moon

More on Full Moon names ---
Link 1 >>> http://earthsky.org/astronomy-essentials/full-moon-names
Link 2 >>> https://en.wikipedia.org/wiki/Full_moon#Farmers.27_Almanacs
Link 3 >>> http://www.farmersalmanac.com/full-moon-names/
 
Image of the Full Moon photographed by the Apollo 11 astronauts in July of 1969, during the spacecraft's trans-Earth journey homeward after the first landing of astronauts on the Moon, approximately 10,000 nautical miles from the Earth
(Image Source: NASA):
Link >>> http://spacewatchtower.blogspot.com/2015/12/astronomical-calendar-2015-december.html

Source: Glenn A. Walsh Reporting for SpaceWatchtower, a project of Friends of the Zeiss.
              Thursday, 2018 December 20.

                             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 --- < http://buhlplanetarium2.tripod.com/weblog/spacewatchtower/gaw/ >
Electronic Mail: < gawalsh@planetarium.cc >
Project Director, Friends of the Zeiss: < http://buhlplanetarium.tripod.com/fotz/ >
SpaceWatchtower Editor / Author: < http://spacewatchtower.blogspot.com/ >
Formerly Astronomical Observatory Coordinator & Planetarium Lecturer, original Buhl Planetarium & Institute of Popular Science (a.k.a. Buhl Science Center), Pittsburgh's science & technology museum from 1939 to 1991. Formerly Trustee of the Andrew Carnegie Free Library and Music Hall, Pittsburgh suburb of Carnegie, Pennsylvania.
Author of History Web Sites on the Internet --
* Buhl Planetarium, Pittsburgh:
  < http://www.planetarium.cc >
* Adler Planetarium, Chicago:
  < http://adlerplanetarium.tripod.com >
* Astronomer, Educator, Optician John A. Brashear:
  < http://johnbrashear.tripod.com >
* Andrew Carnegie & Carnegie Libraries:
  < http://www.andrewcarnegie.cc >

Friday, December 7, 2018

Contact ET with High-Power Laser & Telescope?

                          
Image of the Unit Telescope 4 (UT4) of the European Southern Observatory's Paranal Observatory in the Atacama Desert of northern Chile. This was the first observatory to use multiple lasers to be the most powerful laser guide stars ever used in astronomy. Now, two space researchers propose using a mega-watt laser, through a large telescope, to signal possible astronomers in other star systems.
(Image Sources: European Southern Observatory, Wikipedia.org)

By Glenn A. Walsh
Reporting for SpaceWatchtower

Could a high-power laser, focused through a telescope, attract the attention of astronomers in distant star systems? Two scientists at the Massachusetts Institute of Technology (MIT) think so.

A paper published in the Astrophysical Journal by MIT scientists James Clark and Dr. Kerri Cahoy proposes that a 1 or 2 mega-watt laser, focused into Outer Space using a 30-to-45-meter telescope, could be enough to signal astronomers as far away as 20,000 light-years!

The idea is that such a strong laser-light would produce a beam of infrared radiation strong enough to stand-out next to the bright light coming from our local star, the Sun. So, if alien astronomers happened to use their telescopes to look toward our Solar System, they would notice an unusually bright light in addition to the light from our Sun.

Mr. Clark, the lead author who is a graduate student in the MIT Department of Aeronautics and Astronautics, told Sci-News.com, “If we were to successfully close a handshake and start to communicate, we could flash a message, at a data rate of about a few hundred bits per second, which would get there in just a few years.”

Of course, this type of communication would only be practical for short distances. If the astronomers were as far as 20,000 light-years away, they would not receive the signal until 20,000 years in the future. And, if they would immediately return such a signal to us, it would take 40,000 years for us to receive the reply!

The first problem with making such a planetary beacon a reality is building lasers and telescopes to the large size requirements necessary. The U.S. Air Force's Airborne Laser, which has been tested as a way to shoot-down ballistic missiles from a military jet, is one example of a laser which could be strong enough for a planetary beacon.

Although no telescope is currently large enough for such a planetary beacon, 24-meter and 39-meter telescopes now under construction in Chile may be large enough for such a project. The Large Magellan Telescope (24-meter) is being built by a consortium of countries led by the United States, and the European Extremely Large Telescope (39-meter) is being built by the European Southern Observatory.

Do extra-terrestrial astronomers, now, have such a planetary beacon which we could find? The MIT scientists determined that a 1-meter telescope on Earth could distinguish such a beacon. But to find it, the telescope would probably have to look directly at the beacon.

Mr. Clark told Sci-News.com, “It is vanishingly unlikely that a telescope survey would actually observe an extraterrestrial laser, unless we restrict our survey to the very nearest stars.”

Internet Links to Additional Information ---

"Megawatt-Class Lasers from Earth Could Attract Alien Astronomers, Says New Study."
Sci-News.com 2018 Nov. 9.
Link >>> http://www.sci-news.com/astronomy/megawatt-class-lasers-alien-astronomers-06591.html

Clark, James R. & Kerri Cahoy. 2018. Optical Detection of Lasers with Near-term Technology at Interstellar Distances. ApJ 867, 97; doi: 10.3847/1538-4357/aae380
Link >>> http://iopscience.iop.org/article/10.3847/1538-4357/aae380

Source: Glenn A. Walsh Reporting for SpaceWatchtower, a project of Friends of the Zeiss.
              Friday, 2018 December 7.

                             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 --- < http://buhlplanetarium2.tripod.com/weblog/spacewatchtower/gaw/ >
Electronic Mail: < gawalsh@planetarium.cc >
Project Director, Friends of the Zeiss: < http://buhlplanetarium.tripod.com/fotz/ >
SpaceWatchtower Editor / Author: < http://spacewatchtower.blogspot.com/ >
Formerly Astronomical Observatory Coordinator & Planetarium Lecturer, original Buhl Planetarium & Institute of Popular Science (a.k.a. Buhl Science Center), Pittsburgh's science & technology museum from 1939 to 1991. Formerly Trustee of the Andrew Carnegie Free Library and Music Hall, Pittsburgh suburb of Carnegie, Pennsylvania.
Author of History Web Sites on the Internet --
* Buhl Planetarium, Pittsburgh:
  < http://www.planetarium.cc >
* Adler Planetarium, Chicago:
  < http://adlerplanetarium.tripod.com >
* Astronomer, Educator, Optician John A. Brashear:
  < http://johnbrashear.tripod.com >
* Andrew Carnegie & Carnegie Libraries:
  < http://www.andrewcarnegie.cc >

Saturday, December 1, 2018

Astronomical Calendar: 2018 December

                               https://upload.wikimedia.org/wikipedia/commons/b/b2/Bennu_at_300_pixels.png
Image of the Asteroid 101955 Bennu, an Apollo asteroid (a group of near-Earth asteroids which cross the Earth's orbit) discovered by the LINEAR Project on 1999 September 11. NASA's OSIRIS-REx spacecraft is expected to enter orbit around Bennu on December 3 at 11:45 a.m. EST / 16:45 UTC, for a two-year mission which will include scooping-up a sample of surface material and returning the sample to Earth about three years afterward. NASA will provide live coverage of the space probe's arrival at the asteroid; more information:
Link >>> https://www.nasa.gov/press-release/nasa-provides-live-coverage-of-spacecraft-arrival-at-asteroid-that-may-have-answers-to
(Image Sources: NASA, Wikipedia.org, By OSIRIS-REx Spacecraft - asteroidmission.org (NASA), Public Domain, https://commons.wikimedia.org/w/index.php?curid=74604130)

Astronomical Calendar for 2018 December ---
Link >>> http://buhlplanetarium4.tripod.com/astrocalendar/2018.html#dec


 Related Blog Post ---

"Astronomical Calendar: 2018 November." 2018 Nov. 1.

Link >>> https://spacewatchtower.blogspot.com/2018/11/astronomical-calendar-2018-november.html


Source: Friends of the Zeiss.
              Saturday, 2018 December 1.

                             Like This Post?  Please Share!

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

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

gaw

Glenn A. Walsh --- < http://buhlplanetarium2.tripod.com/weblog/spacewatchtower/gaw/ >
Electronic Mail: < gawalsh@planetarium.cc >
Project Director, Friends of the Zeiss: < http://buhlplanetarium.tripod.com/fotz/ >
SpaceWatchtower Editor / Author: < http://spacewatchtower.blogspot.com/ >
Formerly Astronomical Observatory Coordinator & Planetarium Lecturer, original Buhl Planetarium & Institute of Popular Science (a.k.a. Buhl Science Center), Pittsburgh's science & technology museum from 1939 to 1991. Formerly Trustee of the Andrew Carnegie Free Library and Music Hall, Pittsburgh suburb of Carnegie, Pennsylvania.
Author of History Web Sites on the Internet --
* Buhl Planetarium, Pittsburgh:
  < http://www.planetarium.cc >
* Adler Planetarium, Chicago:
  < http://adlerplanetarium.tripod.com >
* Astronomer, Educator, Optician John A. Brashear:
  < http://johnbrashear.tripod.com >
* Andrew Carnegie & Carnegie Libraries:
  < http://www.andrewcarnegie.cc >