Dec. 31: Added Leap-Second at Very End of Leap-Year

By Glenn A. Walsh

Reporting for SpaceWatchtower

Every four years (usually), the calendar year is longer by 24 hours than the previous three years. However this Leap-Year of 2016 will be even longer, by one second, with the addition of a Leap-Second at the very end of the year as determined by Coordinated Universal Time (UTC).

On July 6, the U.S. Naval Observatory in America (after a decision made by the International Earth Rotation and Reference Systems Service) announced that a Leap-Second would be added to the civil time scale on Saturday Evening, 2016 December 31 at 23:59:60 Coordinated Universal Time (UTC) / 6:59:60 p.m. Eastern Standard Time (EST). Leap-Seconds are added, occasionally when needed, at either the end of June or the end of December, or both.

As with all Leap-Seconds, the Leap-Second occurs at the end of the day as determined by Coordinated Universal Time. In the case of a December 31 Leap-Second, this means that the Leap-Second will be added at the very end of 2016 in the Western Hemisphere of Earth. In the Eastern Hemisphere, where January 1 will take-effect before 23:59:60 UTC, the Leap-Second will occur during the first day of 2017.

Coordinated Universal Time (sometimes referred to as Greenwich Mean Time or Greenwich Civil Time), an international time scale used by most of the world's scientists, is configured to begin the day at the Prime Meridian at the Royal Greenwich Observatory (commissioned by King Charles II in 1675) in Greenwich, England, five miles southeast of central London. This is the legacy of the time several centuries ago when Great Britain was the world's foremost seafaring power.

Since the first Leap-Second was added in June of 1972, 26 Leap-Seconds have been added over the years. Leap-Seconds added in both June and December of the same year have occurred only once, thus far: in 1972, the year Leap-Seconds commenced. The last Leap-Second was added on 2015 June 30 at 23:59:60 UTC / 7:59:60 p.m. Eastern Daylight Saving Time (EDT).

Leap-Seconds have been added, periodically, to respond to the continual slowing of the rotation rate of the Earth, so the world's clocks do not vary significantly from the normal sunrise and sunset times throughout the year. Tidal forces from the Moon (and to a lesser extent, the Sun), in addition to the well-known ocean tides, work to slow the Earth's rotation rate. Geologic conditions that change the distribution of the Earth's mass, such as the movement of the Earth's crust relative to its core, are a contributing factor to slowing of the rotation rate.

In theory, a negative Leap-Second, retracting one second at the end of June or December, is also possible. This would occur if the Earth's rotation rate started accelerating. However, there has never been a need for a negative Leap-Second.

The slowing of the Earth's rotation rate is not consistent, and hence, Leap-Seconds are irregularly spaced and unpredictable. No Leap-Seconds were added between the Leap-Second of 1998 December 31 and the Leap-Second of 2005 December 31, while Leap-Seconds were added each year from 1972 to 1979 (including the two Leap-Seconds in 1972). The International Earth Rotation and Reference Systems Service (IERS), based in Frankfurt, Germany, usually decides to install a Leap-Second in the time scale about six months in advance of implementation.

Of course, the Earth's rotation rate does not suddenly slow down by one second, at certain intervals. The Earth's rotation rate has been continually slowing down, and this continues to be monitored by scientists.

Currently, the Earth's rotation rate, measured as UT1 (Universal Time-1 - Mean Solar Time at the Prime Meridian in Greenwich, England), is behind scientists' more consistent UTC [derived from International Atomic Time (TAI), determined by atomic clocks] by four-tenths of a second (clock correction known as DUT1, which is UT1 minus UTC). So, for the civil time scale to stay more consistent with the Earth's rotation rate, a Leap-Second is needed to slow down UTC by one second.

Once the Leap-Second takes effect (at 23:59:60 UTC on Saturday, 2016 December 31), this would make the Earth's rotation rate in advance of UTC by six-tenths of a second. Then, it may take a couple years for the Earth to slow down enough, to the point where UT1 would again be behind UTC and another Leap-Second would be needed. UTC is never allowed to advance more than nine-tenths of a second ahead of UT1, although usually a Leap-Second is added long before that could happen.

Leap-Seconds have proven to be a problem for computers. Hence, in 2005 there was a proposal to eliminate Leap-Seconds, possibly replacing them with Leap-Hours as a way to keep the civil time scale in-sync with the Earth's rotation rate. However, this issue has been quite controversial among scientists and government officials, so the decision to make any change has been delayed.

Precise time signals, which will include the Leap-Second on December 31 as well as the daily DUT correction, are now provided by government agencies via radio, telephone, and the Internet. This includes agencies such as the U.S. Naval Observatory (USNO), National Institute of Standards and Technology (NIST) [originally known as the National Bureau of Standards (NBS)] of the U.S. Department of Commerce, and the National Research Council (NRC) of Canada. Earlier in the 19^th century, the Allegheny Observatory in Pittsburgh provided precise time signals to the railroads and some cities via the telegraph.

Radio time signals, with voice announcements each minute, are provided by three short-wave radio stations in North America: WWV in Fort Collins, Colorado and WWVH in Kekaha, Kauai, Hawaii, both operated by the National Institute of Standards and Technology, and CHU in Ottawa, Ontario, operated by the National Research Council of Canada. Radio-controlled clocks automatically receive the precise time from NIST-operated, long-wave radio station WWVB in Fort Collins, Colorado.

Internet Links to Additional Information ---

More on the Leap-Second -
Link 1 >>> http://www.timeanddate.com/time/leapseconds.html
Link 2 >>> https://en.wikipedia.org/wiki/Leap_second
Link 3 >>> http://earthsky.org/human-world/leap-second-june-30-december-31-why-need-controversy

More on Universal Time (including UT1 & UTC):
Link >>> http://en.wikipedia.org/wiki/Universal_Time

More on Coordinated Universal Time:
Link >>> http://en.wikipedia.org/wiki/Coordinated_Universal_Time

More on International Atomic Time:
Link >>> http://en.wikipedia.org/wiki/International_Atomic_Time

International Earth Rotation and Reference Systems Service (IERS):
Link >>> https://en.wikipedia.org/wiki/International_Earth_Rotation_and_Reference_Systems_Service

Royal Greenwich Observatory:
Link >>> https://en.wikipedia.org/wiki/Royal_Observatory%2C_Greenwich

More on precise, international radio time services ---

WWV (SW), Fort Collins, Colorado (Voice announcements of precise time):
Link >>> https://en.wikipedia.org/wiki/WWV_%28radio_station%29

WWVH (SW), Kekaha, Kauai, Hawaii (Voice announcements of precise time):
Link >>> https://en.wikipedia.org/wiki/WWVH

CHU (SW), Ottawa, Ontario, Canada (Voice announcements of precise time):
Link >>> https://en.wikipedia.org/wiki/CHU_%28radio_station%29

WWVB (LW), Fort Collins, Colorado (For Radio-Controlled Clocks only):
Link >>> https://en.wikipedia.org/wiki/WWVB

More on precise time via telegraph in the 19th century, from Pittsburgh's Allegheny Observatory:
Link >>> http://spacewatchtower.blogspot.com/2016/03/some-states-to-abandon-daylight-saving.html

Related Blog Posts ---

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

Link >>> http://spacewatchtower.blogspot.com/2016/07/leap-year-to-be-even-longer-w-added.html

"'Leap Second' Tue. Evening Due to Slowing Earth Rotation Rate." 2015 June 30.

Link >>> http://spacewatchtower.blogspot.com/2015/06/leap-second-tue-evening-due-to-slowing.html

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

Link >>> http://spacewatchtower.blogspot.com/2015/01/slowing-of-rotation-rate-necessitates.html

"End of the "Leap Second"?" 2012 Jan. 17.

Link >>> http://spacewatchtower.blogspot.com/2012/01/end-of-leap-second.html

Source: Glenn A. Walsh Reporting for SpaceWatchtower, a project of Friends of the Zeiss.
             2016 December 27.


                                                               
        2016: 75th Year of Pittsburgh's Buhl Planetarium Observatory
     Link >>> http://spacewatchtower.blogspot.com/2016/11/75th-anniversary-americas-5th-public.html

                             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 inbox ?
                Send request to < spacewatchtower@planetarium.cc >.

gaw

Glenn A. Walsh, Project Director, Friends of the Zeiss: < http://buhlplanetarium.tripod.com/fotz/ >
& SpaceWatchtower Editor / Author: < http://buhlplanetarium2.tripod.com/weblog/spacewatchtower/gaw/ >
Electronic Mail - < gawalsh@planetarium.cc >
Astronomy Links: < http://buhlplanetarium.tripod.com/#astrolinks >
Science Links: < http://buhlplanetarium.tripod.com/#sciencelinks >
SpaceWatchtower Twitter News Feed: < https://twitter.com/spacewatchtower >
SpaceWatchtower Blog: < http://spacewatchtower.blogspot.com/ >
LibraryWatchtower Blog: < http://librarywatchtower.blogspot.com >
South Hills Backyard Astronomers Blog: < http://shbastronomers.blogspot.com/ >
Barnestormin Blog: Writing, Essays, Pgh. News, etc.: < http://www.barnestormin.blogspot.com/ >
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 >
* Civil War Museum of Andrew Carnegie Free Library:
  < http://garespypost.tripod.com >
* Duquesne Incline cable-car railway, Pittsburgh:
  < http://inclinedplane.tripod.com >
* Public Transit:
  < http://andrewcarnegie2.tripod.com/transit >

Winter Begins Early Wed.; Ursid Meteors Peak Wed. Night

This graphic generally shows the location and configuration of the Earth, in relation to the Sun, at
the times of Solstices and Equinoxes during the year.
(Graphic Source: ©1999, Eric G. Canali, former Floor 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 December Solstice tomorrow morning (Wednesday, 2016 December 21) at 5:44 a.m. Eastern Standard Time (EST) / 10:44 Coordinated Universal Time (UTC). This moment also marks the astronomical beginning of the Summer season in the Southern Hemisphere.

Tomorrow evening / early Thursday morning will mark the best time to see the annual Ursid Meteor Shower. This meteor shower peaks Thursday, 2016 December 22 at 4:00 a.m. EST / 9:00 UTC.

                                               Winter Solstice 2016

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 17^th 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.

Special Thanks: Eric G. Canali, former Floor 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/

Source: Glenn A. Walsh Reporting for SpaceWatchtower, a project of Friends of the Zeiss.
             2016 December 20.


                                                               
        2016: 75th Year of Pittsburgh's Buhl Planetarium Observatory
     Link >>> http://spacewatchtower.blogspot.com/2016/11/75th-anniversary-americas-5th-public.html

                             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 inbox ?
                Send request to < spacewatchtower@planetarium.cc >.

gaw

Glenn A. Walsh, Project Director, Friends of the Zeiss: < http://buhlplanetarium.tripod.com/fotz/ >
& SpaceWatchtower Editor / Author: < http://buhlplanetarium2.tripod.com/weblog/spacewatchtower/gaw/ >
Electronic Mail - < gawalsh@planetarium.cc >
Astronomy Links: < http://buhlplanetarium.tripod.com/#astrolinks >
Science Links: < http://buhlplanetarium.tripod.com/#sciencelinks >
SpaceWatchtower Twitter News Feed: < https://twitter.com/spacewatchtower >
SpaceWatchtower Blog: < http://spacewatchtower.blogspot.com/ >
LibraryWatchtower Blog: < http://librarywatchtower.blogspot.com >
South Hills Backyard Astronomers Blog: < http://shbastronomers.blogspot.com/ >
Barnestormin Blog: Writing, Essays, Pgh. News, etc.: < http://www.barnestormin.blogspot.com/ >
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 >
* Civil War Museum of Andrew Carnegie Free Library:
  < http://garespypost.tripod.com >
* Duquesne Incline cable-car railway, Pittsburgh:
  < http://inclinedplane.tripod.com >
* Public Transit:
  < http://andrewcarnegie2.tripod.com/transit >

Book: "Einstein for Anyone: A Quick Read"

                                

Amateur Astronomers Association of Pittsburgh (AAAP) Co-Founder
Leo J. Scanlon (left), who would later become one of the first Buhl
Planetarium lecturers, thanks Albert Einstein (right) for visiting the
AAAP booth at the 1934 convention of the American Association for
the Advancement of Science at Mellon Institute in Pittsburgh.
More Information: Link >>> http://old.3ap.org/features/leo/leoScanlonBio6.shtml
(Sources: AAAP, Scanlon Family Collection; Photo Reproduction: © Copyright David Smith)

By Glenn A. Walsh

Reporting for SpaceWatchtower

Need a last-minute stocking-stuffer for the Science-minded relative or friend?

David R. Topper, Senior Scholar of the History of Science at the University of Winnipeg, has just introduced the second revised edition of his biography of Albert Einstein, titled, Einstein for Anyone: A Quick Read. Dr. Topper has expanded this paperback edition, and he says it is 35 per cent longer than the original book published exactly a year ago (and, he says, this edition is 40 per cent less expensive than the original book! - Internet link to the publisher's web site, regarding the book, at the end of this blog-post).

According to the promotional Internet web page for the book, “Here is the compact story of this famous man, from the smiling contrarian in his grade school picture to the nonconformist adult who refused to groom his hair.”

The book examines the life of Albert Einstein in three general sections. First is his personal life, including his parents, his two wives, and his children. Next, Dr. Topper examines his struggles as a young Jew, including fleeing Nazi Germany for America, and his devotion to social justice. Finally, he is examined as a scientist, including radical ideas that brought forth a new cosmic model of the universe.

Dr. Topper, who recently (2012 June) retired, was Professor of History at the University of Winnipeg from 1970 to 2012. The Pittsburgh native taught courses in the history of both Science and Art.

He was the recipient of two teaching awards: the Robson Memorial Award for Excellence in Teaching at the University of Winnipeg (1981), and the National 3M Teaching Fellowship (1987). For the journal Leonardo, he has been International Co-Editor (since 1982) and Honorary Editor (since 2005).

Three other books he has published include:

1. Quirky Sides of Scientists: True Tales of Ingenuity and Error from Physics and Astronomy (Springer, 2007)
2. How Einstein Created Relativity from Physics and Astronomy (Springer, 2013)
3. Idolatry and Infinity: Of Art, Math, and God (Brown Walker, 2014)

David Topper, who grew up in Pittsburgh in the 1940s and 1950s, credits Pittsburgh's original Buhl Planetarium and Institute of Popular Science for his interest in Science. He says, "I have very fond memories of the Buhl Planetarium...It stimulated my interest in science and especially astronomy, which has not abated over the years."

Publisher's Internet Web Site - Vernon Press - For the book Einstein for Anyone: A Quick Read:
Link >>> https://vernonpress.com/title?id=228#.WFIrQX21Pdg

Internet Links to Additional Information ---

Regarding David Topper's 2010 Lecture at Carnegie Mellon University in Pittsburgh, about Albert Einstein's visit to the 1934 convention of the American Association for the Advancement of Science at Mellon Institute in Pittsburgh:
Link >>> http://buhlplanetarium.tripod.com/archivenews/releases/einsteinpgh.html

David Topper's Remembrance of Pittsburgh's original Buhl Planetarium and Institute of Popular Science:
Link >>> http://buhlplanetarium4.tripod.com/friendsofthezeiss/HRCnom/support/BuhlDT.htm

Leo J. Scanlon, inventor of the 1st all-aluminum astronomical observatory dome in 1930:
Link >>> http://buhlplanetarium2.tripod.com/bio/ScanlonL.htm

Related Blog Posts ---

"Advanced Interplanetary Laser Altimeter to Map Surface of Mercury."                  2016 October 7. (The interest in the Planet Mercury, by the University of Bern, is inspired by Albert Einstein, who was appointed as a Professor of Theoretical Physics at the University in 1909.)

Link >>> http://spacewatchtower.blogspot.ch/2016/10/advanced-interplanetary-laser-altimeter.html

 

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

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

 

"Einstein's Gravity Theory Passes Toughest Test Yet." 2013 April 27.

Link >>> http://spacewatchtower.blogspot.com/2013/04/einsteins-gravity-theory-passes.html

 

"Einstein Right Again: Dead Star Warps Light." 2013 April 6.

Link >>> http://spacewatchtower.blogspot.com/2013/04/einstein-right-again-dead-star-warps.html

 

"Pics of Einstein's Brain; Tycho Brahe Not Poisoned." 2012 Nov. 16.

Link >>> http://spacewatchtower.blogspot.com/2012/11/pics-of-einsteins-brain-tycho-brahe-not.html

Source: Glenn A. Walsh Reporting for SpaceWatchtower, a project of Friends of the Zeiss.
             2016 December 15.


                                                               
        2016: 75th Year of Pittsburgh's Buhl Planetarium Observatory
     Link >>> http://spacewatchtower.blogspot.com/2016/11/75th-anniversary-americas-5th-public.html

                             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 inbox ?
                Send request to < spacewatchtower@planetarium.cc >.

gaw

Glenn A. Walsh, Project Director, Friends of the Zeiss: < http://buhlplanetarium.tripod.com/fotz/ >
& SpaceWatchtower Editor / Author: < http://buhlplanetarium2.tripod.com/weblog/spacewatchtower/gaw/ >
Electronic Mail - < gawalsh@planetarium.cc >
Astronomy Links: < http://buhlplanetarium.tripod.com/#astrolinks >
Science Links: < http://buhlplanetarium.tripod.com/#sciencelinks >
SpaceWatchtower Twitter News Feed: < https://twitter.com/spacewatchtower >
SpaceWatchtower Blog: < http://spacewatchtower.blogspot.com/ >
LibraryWatchtower Blog: < http://librarywatchtower.blogspot.com >
South Hills Backyard Astronomers Blog: < http://shbastronomers.blogspot.com/ >
Barnestormin Blog: Writing, Essays, Pgh. News, etc.: < http://www.barnestormin.blogspot.com/ >
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 >
* Civil War Museum of Andrew Carnegie Free Library:
  < http://garespypost.tripod.com >
* Duquesne Incline cable-car railway, Pittsburgh:
  < http://inclinedplane.tripod.com >
* Public Transit:
  < http://andrewcarnegie2.tripod.com/transit >

Celestial Navigation Classes Return to Naval Academy After Absence of Nearly a Decade

This photograph shows a U.S. Naval Officer, at sea, practicing Celestial Navigation with a sextant.
[Image Sources: U.S. Navy (Photographer: Mass Communication Specialist 2nd Class Scott Raegen), Sky and Telescope Magazine]

By Glenn A. Walsh

Reporting for SpaceWatchtower

Like many civilians, the U.S. Navy finds GPS (Global Positioning System) an easy and convenient way to determine the location of their ships at sea. However, classes in the age-old science of Celestial Navigation have returned to the U.S. Naval Academy in Annapolis, Maryland, as a back-up method in case of some technological failure in the GPS equipment.

Training in Celestial Navigation was standard for all midshipmen ever since the U.S. Naval Academy opened on 1845 October 10. However, the use of GPS equipment became so easy and extremely precise that the Navy ROTC ended Celestial Navigation training in 2000 and the Naval Academy stopped teaching Celestial Navigation in 2006.

While the Pentagon's Defense Advanced Research Projects Agency (DARPA) helped develop GPS technology for the military in February of 1978, the U.S. Department of Defense and the Navy are now recognizing several technological vulnerabilities of GPS. In time of war or national emergency, enemies of the United States could attack and disable GPS satellites by missile or an electronics-disabling EMP (Electromagnetic Pulse) attack. Space debris could also knock-out a GPS satellite. Additionally, commercial GPS jammers can now be purchased on the Internet.

A major solar flare could have the same effect as an EMP attack and knock-out the circuitry on GPS satellites. Such major solar activity has affected electronics in the past, including solar storms in 1921 and 1960 which disrupted radio communication. A major solar flare in March of 1989 knocked-out the power-grid in a large part of Quebec Province in Canada. And, a huge solar flare known as a CME (Coronal Mass Ejection) in September of 1859 (known as the Carrington Event) caused major disruptions of telegraph systems around the world (even causing small fires in some telegraph offices). Further, NASA observed a similarly-sized CME in July of 2012, but the trajectory of this particular solar flare missed the Earth.

Classes in Celestial Navigation returned to the Naval Academy in the Summer of 2015. The graduating class of 2017 will be first in more than a decade to be trained in Celestial Navigation theory.

Since the beginning of recorded history, or perhaps even before, mankind has used the stars to help find their way. Many of the stars have Arabic names, because people crossing deserts used stars as direction-finders.

Homer's Odyssey is the first written record of the use of navigating by the stars. Calypso told Odysseus, as he sailed on the ocean eastward from her island Ogygia, to keep the bear (Constellation Ursa Major) on his left side, while observing the positions of the Pleiades (star cluster), the late-setting Bootes the Herdsman (constellation) and Orion the Hunter (constellation).

Celestial Navigation, also known as Astronavigation, is the method of using celestial bodies and angular measurements to determine a particular location on land or at sea. When using Celestial Navigation, the goal is to derive the latitude and longitude of the location desired. Three tools are used for Celestial Navigation:

1. Sextant – invented in 1731, an astronomical instrument which determines latitude and longitude by measuring angular distances, particularly the altitudes of celestial objects.
2. Nautical Almanac – first one published in 1766, provides tables and charts providing astronomical data to assist with Celestial Navigation.
3. Chronometer – invented in 1761, timepiece with a special mechanism for ensuring and adjusting its accuracy, for use in determining longitude.

To obtain the latitude of a ship, a sextant would be used to measure the angular distance between a celestial object and the horizon, at a specific time. This information can be used to “fix” the latitude on a nautical chart.

While sailors mostly use the Sun for latitude readings, the Moon, a planet, or one of 57 navigational stars are also used. The most popular “Guide Star” is Polaris, also known as the North Star in current times (over thousands of years, other stars have been, and will be again, known as the North Star). Other popular Guide Stars include Arcturus, Antares, Canopus (2^nd brightest star in the night sky), and Sirius (brightest star in the night sky).

To determine the longitude before invention of the marine chronometer, sailors would use the sextant to measure the angular distance between the Moon and planets or bright stars (called the “lunar distance”). Then, with the use of a nautical almanac, they could calculate the Greenwich Mean Time (today, known as Coordinated Universal Time or UTC). By comparing the calculated time to the local time measured on-board the ship, they can derive the longitude of the ship.

A nautical almanac for mariners has been published each year, for the last 250 years. The British Nautical Almanac and Astronomical Ephemeris started publication in 1766. Starting with the calculations for the year 1855, the United States began publishing The American Ephemeris and Nautical Almanac. Over the years, these annual almanacs have had name changes. In 1981, the American and British publications merged to become the annual Astronomical Almanac.

In 1940, Columbia University Astronomer Wallace J. Eckert became Director of the U.S. Naval Observatory, and the Pittsburgh native immediately took charge of producing the annual The American Ephemeris and Nautical Almanac. As war had already broken-out in Europe, the Navy had a greater demand for navigation tables. This prompted Dr. Eckert to automate the process using punched cards in a mechanical computer to generate the needed astronomical calculations, a system he had pioneered at Columbia University with the assistance of IBM. Previously, all of these calculations had been done by-hand.

However, marine navigation was no longer the only challenge he had to deal with. Air power was very important during World War II. So, Dr. Eckert found the need to create a separate Air Almanac, as the usual techniques for marine Celestial Navigation required too much time for aircraft navigators.

The Air Almanac was published three times a year beginning in 1941, with 730 pages of tables and charts showing the positions of the Sun, Moon, planets, and other objects at 10-minute intervals for every day of the year (today, it is available for free via .pdf file download, or can be purchased on a CD-ROM). This additional information, which had to be accurate, was critical, as even a small error could send an aircraft far in the wrong direction. And, the mechanical computers helped to provide the additional accuracy that was required.

Later, after America entered World War II, a colleague of Dr. Eckert, Columbia University Professor Dana P. Mitchell, who worked on the Manhattan Project at Los Alamos National Laboratory, suggested that Dr. Eckert's IBM mechanical computers could be used for physics research. Nicholas Metropolis and Richard Feynman set-up a punch-card system, which helped develop the first atomic bombs.

During World War II several planetaria, including Pittsburgh's original Buhl Planetarium and Institute of Popular Science, taught Celestial Navigation classes to military servicemen bound for service in the War. In fact, Buhl Planetarium premiered a public planetarium program on Celestial Navigation, titled “Bombers By Starlight,” just two and one-half weeks before the surprise Japanese attack on Pearl Harbor, Hawaii on 1941 December 7 – 75 years ago, today.

This new “sky show” premiered on 1941 November 19, the same evening when famous astronomer Harlow Shapley (then Director of the Harvard College Observatory) gave the keynote address at the dedication of Buhl Planetarium's new, and rather unique, 10-inch Siderostat-Type Refractor Telescope. And after the sky show, a new Buhl Planetarium gallery exhibit opened, with the-then intriguing title, “Can America Be Bombed?”

Dr. Eckert continued helping guide aircraft pilots long after the end of World War II. In fact, NASA used his calculations of the Moon's orbit to guide Apollo astronauts to the Moon in the 1960s and 1970s.

However, the Apollo astronauts were also trained in Celestial Navigation for their missions to the Moon, in case a loss of communication with Mission Control in Houston meant they had to navigate their way home on their own.

Special Note: This article was reprinted in the 2017 March issue (Volume 46, Number 1, Pages 56 to 58, of the .pdf file) of the Quarterly Journal of the International Planetarium Society, Planetarian.

Internet links to additional information ---

Celestial Navigation: Link >>> https://en.wikipedia.org/wiki/Celestial_navigation

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

Astronomical Almanac: Link >>> https://en.wikipedia.org/wiki/Astronomical_Almanac

U.S. Naval Academy: Link >>> https://en.wikipedia.org/wiki/United_States_Naval_Academy

EMP (Electromagnetic Pulse): Link >>> https://en.wikipedia.org/wiki/Electromagnetic_pulse

1859 Carrington Solar Flare Event: Link >>> https://en.wikipedia.org/wiki/Solar_storm_of_1859

Cain, Fraser. "What Was The Carrington Event?"
UniverseToday.com 2017 Jan. 17.
Link >>> http://www.universetoday.com/132890/what-was-the-carrington-event/

CME (Coronal Mass Ejection): Link >>> https://en.wikipedia.org/wiki/Coronal_mass_ejection

Columbia University Professor Wallace J. Eckert:
Link >>> https://en.wikipedia.org/wiki/Wallace_John_Eckert

Buhl Planetarium:
Link >>> http://spacewatchtower.blogspot.com/2014/10/75th-anniversary-of-americas-5th-major.html

Buhl Planetarium Observatory:
Link >>> http://spacewatchtower.blogspot.com/2016/11/75th-anniversary-americas-5th-public.html

Related Blog Posts ---

"Astronomical Calendar: 2016 December." 2016 Dec. 1.

(Includes rare color photograph of Pearl Harbor attack from 75 years ago.)

Link >>> http://spacewatchtower.blogspot.com/2016/12/astronomical-calendar-2016-december.html

"75th Anniversary: America's 5th Public Observatory." 2016 Nov. 19.

(Pittsburgh's original Buhl Planetarium Observatory)

Link >>> http://spacewatchtower.blogspot.com/2016/11/75th-anniversary-americas-5th-public.html

 

"Largest Sunspot in 24 Years Returns for 2nd Month." 2014 Nov. 23.

Link >>> http://spacewatchtower.blogspot.com/2014/11/largest-sunspot-in-24-years-returns-for.html

 

75th Anniversary of America's 5th Major Planetarium." 2014 Oct. 24.

(Pittsburgh's original Buhl Planetarium & Institute of Popular Science)

Link >>> http://spacewatchtower.blogspot.com/2014/10/75th-anniversary-of-americas-5th-major.html

"Laser Weapon Funding from Science Fiction Book?" 2013 Jan. 27.

(Proposal for funding a Laser Weapon, as a defense against guided-missiles which could carry electronics-disabling EMP capability)

Link >>> http://spacewatchtower.blogspot.com/2013/01/laser-weapon-funding-from-science.html

 

Source: Glenn A. Walsh Reporting for SpaceWatchtower, a project of Friends of the Zeiss.
             2016 December 7.


                                                               
        2016: 75th Year of Pittsburgh's Buhl Planetarium Observatory
     Link >>> http://spacewatchtower.blogspot.com/2016/11/75th-anniversary-americas-5th-public.html

                             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 inbox ?
                Send request to < spacewatchtower@planetarium.cc >.

gaw

Glenn A. Walsh, Project Director, Friends of the Zeiss: < http://buhlplanetarium.tripod.com/fotz/ >
& SpaceWatchtower Editor / Author: < http://buhlplanetarium2.tripod.com/weblog/spacewatchtower/gaw/ >
Electronic Mail - < gawalsh@planetarium.cc >
Astronomy Links: < http://buhlplanetarium.tripod.com/#astrolinks >
Science Links: < http://buhlplanetarium.tripod.com/#sciencelinks >
SpaceWatchtower Twitter News Feed: < https://twitter.com/spacewatchtower >
SpaceWatchtower Blog: < http://spacewatchtower.blogspot.com/ >
LibraryWatchtower Blog: < http://librarywatchtower.blogspot.com >
South Hills Backyard Astronomers Blog: < http://shbastronomers.blogspot.com/ >
Barnestormin Blog: Writing, Essays, Pgh. News, etc.: < http://www.barnestormin.blogspot.com/ >
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 >
* Civil War Museum of Andrew Carnegie Free Library:
  < http://garespypost.tripod.com >
* Duquesne Incline cable-car railway, Pittsburgh:
  < http://inclinedplane.tripod.com >
* Public Transit:
  < http://andrewcarnegie2.tripod.com/transit >

Astronomical Calendar: 2016 December

In a rare color photograph from 75 years ago, Navy sailors save another sailor who jumped overboard after a Japanese torpedo hit the USS West Virginia, which sank next to the USS Tennessee, during the surprise attack on Pearl Harbor, Hawaii on 1941 December 7. Just two and one-half weeks earlier, during the activities surrounding the dedication of a unique 10-inch Siderostat-Type Refractor Telescope at Pittsburgh's original Buhl Planetarium and Institute of Popular Science, a new Buhl Planetarium gallery exhibit also opened with the-then intriguing title, "Can America Be Bombed?"
More on the Attack on Pearl Harbor:
Link >>> https://en.wikipedia.org/wiki/Attack_on_Pearl_Harbor
More on the 10-inch Siderostat-Type Refractor Telescope at Pittsburgh's original Buhl Planetarium:
Link >>> http://spacewatchtower.blogspot.com/2016/11/75th-anniversary-americas-5th-public.html [Image Sources: Associated Press (photographer unknown), BuzzFeed.com ]

Astronomical Calendar for 2016 December: 
Link >>> http://buhlplanetarium4.tripod.com/astrocalendar/2016.html#dec

Source: Friends of the Zeiss.
             2016 December 1.


                                                               
        2016: 75th Year of Pittsburgh's Buhl Planetarium Observatory
     Link >>> http://spacewatchtower.blogspot.com/2016/11/75th-anniversary-americas-5th-public.html

                             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 inbox ?
                Send request to < spacewatchtower@planetarium.cc >.

gaw

Glenn A. Walsh, Project Director, Friends of the Zeiss: < http://buhlplanetarium.tripod.com/fotz/ >
& SpaceWatchtower Editor / Author: < http://buhlplanetarium2.tripod.com/weblog/spacewatchtower/gaw/ >
Electronic Mail - < gawalsh@planetarium.cc >
Astronomy Links: < http://buhlplanetarium.tripod.com/#astrolinks >
Science Links: < http://buhlplanetarium.tripod.com/#sciencelinks >
SpaceWatchtower Twitter News Feed: < https://twitter.com/spacewatchtower >
SpaceWatchtower Blog: < http://spacewatchtower.blogspot.com/ >
LibraryWatchtower Blog: < http://librarywatchtower.blogspot.com >
South Hills Backyard Astronomers Blog: < http://shbastronomers.blogspot.com/ >
Barnestormin Blog: Writing, Essays, Pgh. News, etc.: < http://www.barnestormin.blogspot.com/ >
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 >
* Civil War Museum of Andrew Carnegie Free Library:
  < http://garespypost.tripod.com >
* Duquesne Incline cable-car railway, Pittsburgh:
  < http://inclinedplane.tripod.com >
* Public Transit:
  < http://andrewcarnegie2.tripod.com/transit >