Friday, December 20, 2019

Winter Begins Late Sat. Night; Ursid Meteor Shower Sun. Night

   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 (Pittsburgh's science & technology museum 1939-1991) 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, late Saturday Evening, 2019 December 21 at 11:19 p.m. Eastern Standard Time (EST) / December 22, 4:19 Coordinated Universal Time (UTC). This moment also marks the astronomical beginning of the Summer season in the Southern Hemisphere.

Almost 24 hours later, Sunday evening / Monday morning will mark the peak time for the annual Ursid Meteor Shower. This meteor shower peaks Sunday Evening, 2019 December 22 at 10:00 p.m. EST / December 23, 3:00 UTC.

                                               Winter Solstice 2019

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, 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, 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.

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.

                                              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.

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 Post ---

"2019 Summer Begins at Moment of Solstice, Mid-Day." Fri., 2019 June 21.

Link >>> https://spacewatchtower.blogspot.com/2019/06/2019-summer-begins-at-moment-of.html


Source: Glenn A. Walsh Reporting for SpaceWatchtower, a project of Friends of the Zeiss.
              Friday, 2019 December 20.

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gaw

Glenn A. Walsh, Informal Science Educator & Communicator:
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, 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 7, 2019

Laser Space Probe Finds the Unexpected

https://www.nasa.gov/sites/default/files/thumbnails/image/lpf_artist_impression_2015-11-24.jpg
Artist's rendering of the LISA Pathfinder space probe approaching solar orbit.
(Image Source: European Space Agency / C. Carreau)

By Glenn A. Walsh
Reporting for SpaceWatchtower

A laser space probe, designed as a space-based, proof-of-concept mission for finding gravitational-waves, has now been used to map microscopic dust shed by comets and asteroids. This is a clear demonstration that 'empty space' between stars and planetary bodies is not really all that empty!

Due to the space probe's extreme sensitivity, a requirement for the detection of gravitational-waves, NASA scientists have used data from the European Space Agency's (ESA) LISA Pathfinder spacecraft to detect 54 micrometeroid impacts on the spacecraft during the 2015 to 2017 time-frame. The micrometeroids detected are extremely small.

Their masses are measured in micrograms and are similar in size to grains of sand. This cosmic dust was actually smaller than the dust from comets that cause most meteor showers. However, they hit the spacecraft at approximate speeds of 40,000 miles-per-hour / 64,000 kilometers-per-hour, which could injure a spacecraft if the particles had been larger.

NASA scientists, headed by Ira Thorpe of the Goddard Space Flight Center in Greenbelt, Maryland, used modeling to determine where the micrometeroids originate. Their research was published in the September issue of the Astrophysical Journal, the prestigious publication founded in 1895 by George Ellery Hale, who would become Director of the Mount Wilson Observatory, and James E. Keeler, Director of the Allegheny Observatory.

The NASA scientists found that most of the micrometeroids come from short-period comets, whose orbits are determined by Jupiter; this is consistent with current ideas regarding micrometeroids near Earth. However, LISA Pathfinder also detected dust from some long-period comets, similar to the famous Halley's Comet.

These results will help in predicting impact risks for current and future spacecraft. They may also help in the understanding of the physics of planet formation.

Launched on 2015 December 3, the LISA Pathfinder mission was to prove the feasibility of a space-based laser interferometer system for finding ripples in space-time caused by, for instance, the merger of black holes. Led by the European Space Agency, with contributions from NASA, the mission was used to test technologies necessary for a space-based observatory that would do what the ground-based LIGO (Laser Interferometer Gravitational-Wave Observatory) has done from the Earth.

LIGO is limited by seismic, thermal, and other sources of noise present on the Earth. It is hoped that a space-based system, without these limitations, would be even more sensitive and find even more gravitational-waves.

The main LISA (Laser Interferometer Space Antenna) mission, expected to be launched around 2034, would consist of a constellation of three spacecraft arranged in an equilateral triangle with sides 1.55 million statute miles / 2.5 million kilometers long, in an orbit around the Sun. By precisely monitoring the distances between each satellite, more ripples in space-time should be detected.

Internet Links to Additional Information ---

LISA Pathfinder Spacecraft: Link >>> https://en.wikipedia.org/wiki/LISA_Pathfinder

LISA Spacecraft (launch in 2034): Link >>> https://en.wikipedia.org/wiki/Laser_Interferometer_Space_Antenna

LIGO Ground-Based Observatory: Link >>> https://en.wikipedia.org/wiki/LIGO

Micrometeroid: Link >>> https://en.wikipedia.org/wiki/Micrometeoroid

Related Blog-Posts ---

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

Link >>> http://spacewatchtower.blogspot.com/2017/10/physics-nobel-prize-awarded-to.html

 

"Laser Gravitational-Wave Observatory Researchers Receive 2 Awards. Sun., 2016 June 5.

Link >>> http://spacewatchtower.blogspot.com/2016/06/laser-gravitational-wave-observatory.html


Source: Glenn A. Walsh Reporting for SpaceWatchtower, a project of Friends of the Zeiss.
              Saturday, 2019 December 7.

                             Like This Post?  Please Share!

           More Astronomy & Science News - SpaceWatchtower Twitter Feed:
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        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:
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, 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 >

Sunday, December 1, 2019

Astronomical Calendar: 2019 Dec. / Centennial: Death of Astronomy Philanthropist H.C. Frick

                     Henry Clay Frick.jpg
December 2 marks the Centennial Anniversary of the death of industrialist and education and astronomical philanthropist Henry Clay Frick. And, December 19 marks the 170th anniversary of his birth. He provided much of the funding for construction of the second, three-dome Allegheny Observatory, dedicated in 1912. He asked astronomer John A. Brashear to organize the Henry Clay Frick Educational Commission, to fund supplemental educational opportunities for public school teachers, as well as provide for free-of-charge, public tours of the Allegheny Observatory several evenings a week during the warm-weather months.
Biography of Henry Clay Frick: Link >>> http://johnbrashear.tripod.com/frick.html
(Image Sources: By Bain News Service - This image is available from the United States Library of Congress's Prints and Photographs divisionunder the digital ID ggbain.07131.This tag does not indicate the copyright status of the attached work. A normal copyright tag is still required. See Commons:Licensing for more information., Public Domain, https://commons.wikimedia.org/w/index.php?curid=700199)

Astronomical Calendar for 2019 December ---
Link >>> http://buhlplanetarium4.tripod.com/astrocalendar/2019.html#dec

 Related Blog Post ---

"Astronomical Calendar: 2019 November / Transit of Mercury Nov. 11"

Friday, 2019 November 1.

Link >>> https://spacewatchtower.blogspot.com/2019/11/astronomical-calendar-2019-november.html


Source: Friends of the Zeiss.
              Sunday, 2019 December 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:
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, 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 >

Wednesday, November 13, 2019

100 Years Ago: U.S. Scientist Questions Evidence Proving General Theory of Relativity

                              https://buhlplanetarium2.tripod.com/bio/einstein/Einstein-Leo-1934AAAS.jpg 

Albert Einstein proposed the General Theory of Relativity in 1915. After an experiment during a solar eclipse, scientists confirmed the theory in 1919. This 1934 photograph shows Dr. Einstein (right) visiting the exhibit booth of the Amateur Astronomers Association of Pittsburgh (AAAP) at the annual conference of the American Association for the Advancement of Science in Pittsburgh. To the front-left of Dr. Einstein is Leo J. Scanlon, AAAP Co-Founder (1929), constructor of the world's first all-aluminum, astronomical observatory dome (1930), and one of the first two Buhl Planetarium lecturers (1939).
(Sources: AAAP, Scanlon Family Collection; Photo Reproduction: © Copyright David Smith)

By Glenn A. Walsh
Reporting for SpaceWatchtower

One-hundred years ago today, on Thursday, 1919 November 13, The New York Times reported that American experimental physicist Robert A. Millikan (who won the 1923 Nobel Prize in physics) questioned the results of a solar eclipse experiment confirming the General Theory of Relativity, at a Connecticut conference of the National Academy of Sciences. Just a week earlier, on Thursday, 1919 November 6, British astronomer Sir Arthur Eddington had released the results of the eclipse experiment which confirmed the General Theory of Relativity, proposed just four years earlier by German theoretical physicist Albert Einstein.

According to The New York Times article (complete text of short article near the end of this blog-post), Dr. Millikan believed that a simpler explanation could explain the solar eclipse experiment results, which would not necessarily confirm the General Theory of Relativity.

It was at a joint meeting of the Royal Society of London and the Royal Astronomical Society, in London on Thursday, 1919 November 6, that Dr. Eddington publicly presented the results of an experiment conducted during the Total Solar Eclipse of Thursday, 1919 May 29. This experiment was conducted to confirm the General Theory of Relativity, and according to Dr. Eddington the experiment did, indeed, confirm Dr. Einstein's new theory.

Over the next few days, following the public presentation of the eclipse experiment results, the world's major newspapers exclaimed how revolutionary the new theory was in providing a new explanation of the Universe, which greatly differs from the explanation given by Sir Isaac Newton centuries earlier.

The headline in The Times of London, on Friday, 1919 November 7, announced:
“Revolution in Science – New Theory of the Universe – Newtonian Ideas Overthrown.”

On Monday, 1919 November 10, The New York Times headline proclaimed:
“LIGHTS ALL ASKEW IN THE HEAVENS
Men of Science More or Less
Agog Over Results of Eclipse
           Observations
EINSTEIN THEORY TRIUMPHS.”

Dr. Einstein became an instant celebrity. This was all the more amazing considering that British scientists had confirmed a German scientist's theory, just after the end of the First World War between the two enemy nations, when there were still bitter feelings on both sides.

On Thursday, 1915 November 25, in the fourth of a weekly series of four lectures, Dr. Einstein completed his General Theory of Relativity before the Prussian Academy of Sciences. Ten years earlier, he had proposed the Special Theory of Relativity.

In his 1905 Special Theory of Relativity, Dr. Einstein described the structure of what he called, “Space-Time,” fusing together the three dimensions of space and the one dimension of time. Dr. Einstein used the Special Theory of Relativity to illustrate the equivalence of energy and mass, thus creating his famous equation: E=mc2.

Dr. Einstein's 1915 General Theory of Relativity described gravitation, as well as matter, space, and time. In this theory, Dr. Einstein first proposed that space-time is curved near the gravitational field of a mass. Thus gravity does not exert a force on an object, as proposed by Sir Isaac Newton; rather the object follows a natural path along a curved surface of space-time, when the object nears a mass.

One consequence of the General Theory of Relativity is light deflection: rays of light bend, even if just slightly, when passing a gravitational field. A real-world test of this hypothesis would demonstrate the validity of the General Theory of Relativity. But, how to test it?

The logical test seemed to be to observe star-light from distant stars and determine whether the star-light was deflected when it passed a massive object, such as a star, planet, our Moon, or our Sun. However, the light deflection is quite minimal and nearly impossible to measure when the star-light passes distant stars, planets, or even our own Moon. And, star-light passing near our Sun could only be observed during a Total Eclipse of the Sun, due to the very bright sky-glow near the Sun.

The very first attempt to measure light deflection was going to be conducted during the Total Solar Eclipse of Friday, 1914 August 21. This attempt was a disaster, as it was planned to occur in Crimea just 20 days after Germany had declared war on Russia, during World War I.

Berlin University astronomy professor Erwin Freundlich and colleagues had left Berlin on Sunday, 1914 July 19, before the Declaration of War. They were arrested as German spies, by the Russians. Their astronomical equipment, considered military surveillance equipment by the Russians, was confiscated. A few weeks later, the Berlin University astronomers were freed during a prisoner exchange.

In a way, this episode was fortunate for Dr. Einstein. His light deflection calculation (0.85 second of arc) for the 1914 eclipse was in error.

By the time Dr. Einstein delivered his third General Theory of Relativity lecture, on Thursday, 1915 November 18, he had corrected the light deflection calculation. The correct calculation was 1.7 seconds of arc, exactly twice the original value.

The first attempt to measure light deflection, after completion of the General Theory of Relativity, came by British astronomers during the Total Solar Eclipse of Saturday, 1918 June 8. However, cloud-cover prevented observations of the stars.

For the Total Solar Eclipse of Thursday, 1919 May 29, Dr. Eddington observed from the island of Principe off of the west coast of Africa, while sending a second observing expedition to Sobral, Brazil. Successful observations (of stars in the Constellation Taurus the Bull) were made from both locations. However, due to the minute deflection of star-light that actually occurred, it took several months to make the mathematical calculations necessary to confirm the General Theory of Relativity.

Finally, Dr. Eddington did publicly announce the results of his solar eclipse experiment on Thursday, 1919 November 6.

However, not all scientists (or even newspaper editorial writers) immediately accepted Dr. Einstein's new theory. In fact, 100 years ago today, on Thursday, 1919 November 13, The New York Times reported, in a mini-editorial on the editorial page (page 12), that Dr. Einstein's theory was questioned by a noted scientist at a New Haven, Connecticut conference of the National Academy of Sciences.

The following is the complete text of this short, two-paragraph article, appearing as the last of four mini-editorials, in the newspaper's regular Topics of the Times column ---

                                             Sir Isaac Finds a Defender

As the now almost famous attack of Dr. EINSTEIN on the Newtonian law of gravitation has been declared successful by many eminent men of science, it is not for the common folk to undertake a defense of the long-revered formula. People, however, who have felt a bit resentful at being told that they couldn't possibly understand the new theory, even if it were explained to them ever so kindly and carefully, will feel a sort of satisfaction on noting that the soundness of the Einstein deduction has been questioned by R.A. MILLIKAN in a paper read before the National Academy of Sciences in session at New Haven.

His plausible suggestion is that the starlight passing the Sun in eclipse was not deflected by gravitational attraction, but was refracted in the perfectly familiar way of light when it entered and emerged from the gases that form the solar atmosphere. That is understandable as well as plausible, and it is hard not to hope that it is true.

                                               Robert Andrews Millikan 1920s.jpg
                                                         Robert A. Millikan
(Image Sources: Wikipedia.org, By Unknown (Mondadori Publishers) - http://www.gettyimages.co.uk/search/2/image?phrase=Robert%20Andrews%20Millikan%20%20mondadori&family=editorial&sort=best&page=1&excludenudity=false, Public Domain, https://commons.wikimedia.org/w/index.php?curid=41222283)

Robert A. Millikan was an American experimental physicist who was honored with the 1923 Nobel Prize in physics, for the measurement of the elementary electric charge and for his work on the photoelectric effect. He became the first president (official title: Chairman of the Executive Council) of the California Institute of Technology (which, today, includes management of the Jet Propulsion Laboratory for NASA) in 1921, serving in that position until 1945.

Internet Links to Additional Information ---

Albert Einstein:
Link 1 >>> http://www.alberteinsteinsite.com/einsteinbiography.html
Link 2 >>> https://en.wikipedia.org/wiki/Albert_Einstein

Sir Arthur Eddington:
Link 1 >>> https://www.famousscientists.org/arthur-eddington/
Link 2 >>> https://en.wikipedia.org/wiki/Arthur_Eddington

Robert A. Millikan:
Link 1 >>> https://www.nobelprize.org/prizes/physics/1923/millikan/biographical/
Link 2 >>> https://en.wikipedia.org/wiki/Robert_Andrews_Millikan

Total Solar Eclipse of Thursday, 1919 May 29:
Link 1 >>> https://eclipse.gsfc.nasa.gov/SEgoogle/SEgoogle1901/SE1919May29Tgoogle.html
Link 2 >>> https://en.wikipedia.org/wiki/Solar_eclipse_of_May_29,_1919

Eddington 1919 Solar Eclipse Experiment:
Link >>> https://en.wikipedia.org/wiki/Eddington_experiment

General Theory of Relativity:
Link 1 >>> https://www.physicsoftheuniverse.com/topics_relativity_general.html
Link 2 >>> https://en.wikipedia.org/wiki/General_relativity

Benningfield, Damond. "Critics." Daily Radio Feature: StarDate.
StarDate.org 2020 Jan. 13. First retrieved 2020 Jan. 13.
Centennial: The New York Times editorial on rocket pioneer Robert Goddard, which was retracted on 1969 July 17. Link >>> https://stardate.org/radio/program/2020-01-13 


Related Blog-Posts ---

"Book: 'Einstein for Anyone: A Quick Read'." Thur., 2016 Dec. 15.

Link >>> https://spacewatchtower.blogspot.com/2016/12/book-einstein-for-anyone-quick-read.html 

 

"Centennial: Einstein's General Theory of Relativity." Wed., 2015 Nov. 25.

Link >>> https://spacewatchtower.blogspot.com/2015/11/centennial-einsteins-general-theory-of.html


Source: Glenn A. Walsh Reporting for SpaceWatchtower, a project of Friends of the Zeiss.
              Wednesday, 2019 November 13.

                             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:
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, 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, November 1, 2019

Astronomical Calendar: 2019 November / Transit of Mercury Nov. 11

     
Image of a Transit of the Planet Mercury across the disk of the Sun on 2016 May 9. The tiny black dot in the lower center of the photograph is Mercury, as it crossed the solar disk in 2016. The dark / gray spot in the upper center of the photo is a sunspot, a large magnetic storm on the surface of the Sun. The next Transit of Mercury takes place this month, on Monday, 2019 November 11.
NEVER LOOK DIRECTLY AT THE SUN UNLESS YOU HAVE THE PROPER EQUIPMENT AND PROPER TRAINING TO DO SO SAFELY!
For more information, and live, on-line coverage of the event, click on the following link ---
Link >>> http://buhlplanetarium4.tripod.com/astrocalendar/2019.html#transitmercury2019

Astronomical Calendar for 2019 November ---
Link >>> http://buhlplanetarium4.tripod.com/astrocalendar/2019.html#nov

 Related Blog Post ---

"Astronomical Calendar: 2019 October / Change in ISS Crew"

Tuesday, 2019 October 1.

Link >>> https://spacewatchtower.blogspot.com/2019/10/astronomical-calendar-2019-october.html


Source: Friends of the Zeiss.
              Friday, 2019 November 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:
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, 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 >

Tuesday, October 15, 2019

For Students: Mars 2020 Name the Rover Essay Contest By Nov. 1


(Image Sources: NASA, Wikipedia.org, By NASA/JPL-Caltech - http://photojournal.jpl.nasa.gov/jpeg/PIA19672.jpg, Public Domain, https://commons.wikimedia.org/w/index.php?curid=40891664)

By Glenn A. Walsh
Reporting for SpaceWatchtower

NASA is offering the Mars 2020 Name the Rover essay contest for Kindergarten to 12th Grade students in public, religious, private, and home schools. The student with the winning essay will name the Mars 2020 Rover and will be invited to watch the launch of the mission at the Cape Canaveral Air Force Station (near the Kennedy Space Center in Florida) in July of 2020.

"This naming contest is a wonderful opportunity for our nation's youth to get involved with NASA's Moon to Mars missions," said NASA Administrator Jim Bridenstine. "It is an exciting way to engage with a rover that will likely serve as the first leg of a Mars Sample return campaign, collecting and caching core samples from the Martian surface for scientists here on Earth to study for the first time."

The deadline for this student essay contest is November 1. By the November 1 deadline, students should submit a short essay (no more than 150 words) giving their proposed name for the Mars 2020 Rover and why this name should be chosen by NASA officials.

Judging the essay contest will be divided by grade level:
  • Kindergarten to 4th Grade
  • 5th to 8th Grade
  • 9th to 12th Grade

Student essays will be judged on the appropriateness, significance and originality of their proposed name, and the originality and quality of their essay. There may be an interview presentation for finalists.

From each of the three grade judging groups, 52 semifinalists will be selected per group, each representing their respective state or U.S. territory. Three finalists then will be selected from each group to advance to the final round.

In January of next year, the public will have the chance to vote, on-line, on the nine finalist Rover name suggestions, from the nine finalist essays which will be posted on the NASA Mars Internet Web-Site. On 2020 February 18 (exactly one year from the 2021 date of the Mars 2020 landing on Mars), NASA plans to announce the winning name for the Mars 2020 Rover.

Go to the following Internet World Wide Web link for complete contest and prize details, and how to enter the essay contest:


NASA is also looking for volunteers to judge the thousands of contest entries expected. U.S. residents, age 18 or older, who can offer about 5 hours of their time to judge the contest entries, should register to be a judge at the following link:


Internet Links to Additional Information ---

Mars 2020 Rover:
Link 1 >>> https://mars.jpl.nasa.gov/mars2020/
Link 2 >>> https://en.wikipedia.org/wiki/Mars_2020

Related Blog-Posts ---

"Place Your Name on Mars 2020 Rover Microchip By This Monday, Sept. 30." 2019 Sept. 26.

Link >>> https://spacewatchtower.blogspot.com/2019/09/place-your-name-on-mars-2020-rover.html

 

"Help Astronomers Name Large Kuiper Belt Asteroid." 2019 April 26.

Link >>> https://spacewatchtower.blogspot.com/2019/04/help-astronomers-name-large-kuiper-belt.html


Source: Glenn A. Walsh Reporting for SpaceWatchtower, a project of Friends of the Zeiss.
              Tuesday, 2019 October 15.

                             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:
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, 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 >

Monday, October 7, 2019

SETI / Breakthrough Listen Now Looking for Laser Beacons From ET


This image shows the mirrors on one of the four 12-meter optical reflectors of the Very Energetic Radiation Imaging Telescope Array System (VERITAS), to be used for scanning the skies for laser communication beacons from extraterrestrial civilizations.
(Image Sources: Wikipedia.org, By Wars - The image was personally taken by me, Wars, on the 3rd of September 2007, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=2680980)    

By Glenn A. Walsh
Reporting for SpaceWatchtower

In the Search for Extraterrestrial Intelligence (SETI), large radio telescopes, such as the telescopes at the National Radio Astronomy Observatory in Green Bank, West Virginia, have been used for decades in the search for radio signals coming from extraterrestrial civilizations. Now, there is a plan to begin looking for possible laser communication beacons originating with extraterrestrial civilizations.

This is not the first time such laser beacons have been searched for. However, a great new tool will now help to greatly advance this search.

The Very Energetic Radiation Imaging Telescope Array System (VERITAS), composed of four
12-meter optical reflector telescopes at the Fred Lawrence Whipple Observatory in Amado, Arizona, will now be used to advance the search for, what are called, 'pulsed optical beacons.' This telescope array is considered particularly useful for this type of research, even though VERITAS was originally designed to study gamma rays coming from Outer Space.

Pulsed optical beacons are strong laser-like pulses of light that are very short in duration (usually only a few nano-seconds per pulse). It is speculated that advanced civilizations may use such optical beacons for long-distance communication instead of radio waves. Such optical communication could provide advanced civilizations with greater band-width for data, as well as be less prone to signal interference and degradation.

NASA has already successfully used laser communication to transit high-definition images from the Moon to the Earth.

It is likely that artificial optical pulses would be brighter than most stars in the same star-field, which would be one way of confirming their artificial nature. And, the use of VERITAS' four telescopes would help to eliminate false positive pulse detections

The SETI Institute has already been involved in an optical communication search using the 40-inch Nickel Telescope in Lick Observatory on Mount Hamilton, California. Adding VERITAS to this project will greatly extend this search. The huge mirror area of the four VERITAS telescopes will provide the ability to receive very faint light signals.

This new search is part of the Breakthough Listen project, which is a part of Breakthrough Initiatives founded in 2015 by entrepreneur Yuri Milner. Based at the Berkeley SETI Research Center in the Astronomy Department of the University of California, Berkeley, it is a $100 million project expected to last at least 10 years.

Internet Links to Additional Information ---

Very Energetic Radiation Imaging Telescope Array System (VERITAS):
Link >>> https://en.wikipedia.org/wiki/VERITAS

Breakthrough Listen: Link >>> https://en.wikipedia.org/wiki/Breakthrough_Listen

Breakthrough Initiatives: Link >>> https://en.wikipedia.org/wiki/Breakthrough_Initiatives

Related Blog Posts ---

"Nano-Space Probes to Star Alpha Centauri by Laser-Sail ?" 2017 Dec. 7.

Link >>> http://spacewatchtower.blogspot.com/2017/12/nano-space-probes-to-star-alpha.html


"Lasers in Space ?" 2017 Nov. 13.

Link >>> http://spacewatchtower.blogspot.com/2017/11/lasers-in-space.htm

 

Source: Glenn A. Walsh Reporting for SpaceWatchtower, a project of Friends of the Zeiss.
              Monday, 2019 October 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, Informal Science Educator & Communicator:
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, 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 >

Tuesday, October 1, 2019

Astronomical Calendar: 2019 October / Change in ISS Crew

                ISS insignia.svg
Early in October there will be two important events aboard the International Space Station ---
October 2: Change of Command ceremony: Russian Cosmonaut Alexey Ovchinin hands over command of the space station to European Space Agency astronaut Luca Parmitano.
October 3: NASA astronaut Nick Hague, Russian cosmonaut Alexey Ovchinin and Hazzaa Ali Almansoori of the United Arab Emirates return to Earth from the International Space Station. Undocking is scheduled: 3:35 a.m. EDT / 7:35 UTC; crew scheduled to land near Dzhezkazgan, Kazakhstan: 6:58 a.m. EDT / 10:58 UTC. As always, NASA-TV will provide full coverage:
Link >>> https://www.nasa.gov/multimedia/nasatv/#public
Above is the official insignia of the International Space Station (ISS).
(Image Sources: NASA, Wikipedia.org, By Original: NASAThis vector version by Mysid - Self-made in Inkscape; based on Image:InternationalSpaceStationPatch.png and http://www.spacefacts.de/iss/p_large/iss_project.htm, Public Domain, https://commons.wikimedia.org/w/index.php?curid=3472226)

Astronomical Calendar for 2019 October ---
Link >>> http://buhlplanetarium4.tripod.com/astrocalendar/2019.html#oct

 Related Blog Post ---

"Astro-Calendar: Sep. / 160th Anniv: Carrington Event Solar Mega-Storm"

Tuesday, 2019 September 3.

Link >>> https://spacewatchtower.blogspot.com/2019/09/astro-calendar-sep-160th-anniv.html


Source: Friends of the Zeiss.
              Tuesday, 2019 October 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:
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, 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, September 26, 2019

Place Your Name on Mars 2020 Rover Microchip By This Monday, Sept. 30


(Image Sources: NASA, Wikipedia.org, By NASA/JPL-Caltech - http://photojournal.jpl.nasa.gov/jpeg/PIA19672.jpg, Public Domain, https://commons.wikimedia.org/w/index.php?curid=40891664)

By Glenn A. Walsh
Reporting for SpaceWatchtower

NASA is launching another rover to the Planet Mars next year, and they want your name to be part of the spacecraft! Until this-coming Monday, September 30, you can arrange to have your name etched on a microchip which will be sent along on the voyage of the Mars 2020 Rover mission.

And, after you register for the microchip, NASA will even give you a souvenir “boarding pass” as well as “frequent flyer points!” According to NASA, on the last Mars mission, Insight, more than 2 million names of members of the general public flew to Mars with the spacecraft, which provided those members of the public about 300 million frequent flyer miles / 500 million frequent flyer kilometers!

The Mars 2020 Rover is a robotic scientist weighing more than 2,300 pounds / 1,000 kilograms. This latest mission to the Red Planet will search for signs of past microbial life, characterize the planet's climate and geology, collect samples for future return to Earth, and pave the way for human exploration. It is scheduled to launch from the Cape Canaveral Air Force Station (near the Kennedy Space Center in Florida) in July of 2020, with a landing on Mars expected in February of 2021.

"As we get ready to launch this historic Mars mission, we want everyone to share in this journey of exploration," said Thomas Zurbuchen, Associate Administrator for NASA's Science Mission Directorate (SMD) in Washington, DC. "It’s an exciting time for NASA, as we embark on this voyage to answer profound questions about our neighboring planet, and even the origins of life itself.”

You can add your name to the list of names to be etched on a microchip to be included with the Mars 2020 Rover mission, and down-load your souvenir “boarding pass,” at the following Internet link. Remember, the deadline to submit your name for this list is this-coming Monday, September 30, 11:59 p.m. Eastern Daylight Saving Time (EDT) / October 1, 3:59 Coordinated Universal Time (UTC) !!!


Internet Links to Additional Information ---

Mars 2020 Rover:
Link 1 >>> https://mars.jpl.nasa.gov/mars2020/
Link 2 >>> https://en.wikipedia.org/wiki/Mars_2020

Related Blog-Post ---

"Help Astronomers Name Large Kuiper Belt Asteroid." 2019 April 26.

Link >>> https://spacewatchtower.blogspot.com/2019/04/help-astronomers-name-large-kuiper-belt.html


Source: Glenn A. Walsh Reporting for SpaceWatchtower, a project of Friends of the Zeiss.
              Thursday, 2019 September 26.

                             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:
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, 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 >

Sunday, September 22, 2019

Autumn Begins at Moment of Equinox Early Monday Morning

   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 Autumnal Equinox, as well as the other equinox and solstices of the year.
(Image 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 Autumnal Equinox, the beginning of the season of Autumn or Fall in the Northern Hemisphere of Earth, begins early Monday morning. In Earth's Southern Hemisphere, this equinox marks the astronomical beginning of the season of Spring.

The September Equinox occurs early Monday Morning, 2019 September 23 at 3:50 a.m. Eastern Daylight Saving Time (EDT) / 7:50 Coordinated Universal Time (UTC).

On the day of Equinox, the Sun appears directly overhead at local Noon on the Equator. At the moment of Equinox, the Northern and Southern Hemispheres of Earth are illuminated equally. And, the time of Equinox is the only time when the Earth Terminator (dividing line on Earth between daylight and darkness) is perpendicular to the Equator.

This, and the reason for seasons on Earth in the first place, is due to the fact that Earth rotates on its axis, which is tilted at an approximate 23.44-degree angle from the plane of the Earth's orbit around the Sun. As the Earth revolves around the Sun, this axial tilt causes one hemisphere of the planet to receive more direct solar radiation during that hemisphere's season of Summer and much less direct solar radiation a half-year later during that hemisphere's season of Winter. As mentioned, during an Equinox (about half-way between Summer and Winter, and about half-way between Winter and Summer) both planetary hemispheres receive an equal amount of solar radiation.

Although "Equinox" in Latin means equal-night, the day of the Equinox does not actually have an equal amount of daylight and nightfall, as it appears on the Earth's surface. If the Sun was just a pin-point of light in our sky, as all other stars appear, day and night would be equal.

But, because the Sun is a disk, part of the Sun has risen above the horizon before the center of the Sun (which would be the pin-point of light); so there are extra moments of light on the Equinox. Likewise, part of the Sun is still visible, after the center of the Sun has set.

Additionally, the refraction of sunlight by our atmosphere causes sunlight to appear above the horizon, before sunrise and after sunset.

September 25 will mark the Equilux ("equal-light"), the actual day with equal hours and minutes of the Sun above the horizon, and equal hours and minutes of the Sun below the horizon. The Equilux occurs twice each year, approximately 3-to-4 days before the Vernal Equinox, when Spring begins,  and 3-to-4 days after the Autumnal Equinox.

An urban legend that has been making the rounds for decades has it that eggs can be stood on their ends only during an Equinox, whether the Vernal Equinox in the Spring or the Autumnal Equinox in the Fall. This is completely false. Depending greatly on the size and shape of the particular egg, eggs can be stood on their ends any day of the year! Astronomy has nothing to do with whether an egg can stand on its end. If an egg can stand on its end on the Equinox (and, due to the shape and size of some eggs, this is not even possible), it can stand the same way any other day of the year.

In the last few years, with the help of the Internet and Social Media, another urban legend has become prevalent. Now it is claimed that brooms can stand, on their own, on their bristles, only on an Equinox day. This is also false. Again, as with eggs, if a broom can stand on its bristles by itself (this usually only works with newer brooms, with more even bristles) on an Equinox, it can do so any day of the year!

September 23 is also designated as the annual Falls Prevention Awareness Day for this year.

Internet Links to Additional Information ---


Season of Autumn or Fall: Link >>> http://en.wikipedia.org/wiki/Autumn

Equinox: Link >>> http://en.wikipedia.org/wiki/Equinox

Earth's Seasons: Link >>> http://en.wikipedia.org/wiki/Season

Tilt of a planet's axis: Link >>> http://en.wikipedia.org/wiki/Axial_tilt

Urban legend of eggs and brooms standing on their own, only on an Equinox:
Link >>> http://www.snopes.com/science/equinox.asp

Falls Prevention Awareness Day: Link >>> http://www.ncoa.org/improve-health/center-for-healthy-aging/falls-prevention/falls-prevention-awareness.html

Related Blog Post ---

 

"2019 Summer Begins at Moment of Solstice, Mid-Day." 2019 June 21.

Link >>> http://spacewatchtower.blogspot.com/2019/06/2019-summer-begins-at-moment-of.html


Source: Glenn A. Walsh Reporting for SpaceWatchtower, a project of Friends of the Zeiss.
              Sunday, 2019 September 22.

                             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:
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, 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 >