Eclipses

"Here lie the bodies of Ho and Hi, Whose fate, though sad, is risible; Being slain because they could not spy Th' eclipse which was invisible." Author unknown: Said to refer to the Chinese eclipse of 2136 BC or 2159 BC. "On the day of the new moon, in the month of Hiyar, the Sun was put to shame, and went down in the daytime, with Mars in attendance." One of the earliest written records of an eclipse of the Sun, on 3 May 1375 BC, found in the city of Ugarit in Mesopotamia.(Reprinted, from Chasing the Shadow, copyright 1994 by Joel K Harris and Richard L Talcott, by permission of Kalmbach Publishing Co. "If the Sun at its rising is like a crescent and wears a crown like the Moon: the king wll capture his enemy's land; evil will leave the land, and (the land) will experience good... " Refers to a solar eclipse of 27 May 669 BC. Rasil the older, Babylonian scribe to the king. Quoted in Historical Eclipses and Earth's Rotation, by F Richard Stephenson, Cambridge University Press, 1997, page 125. "Nothing can be surprising any more or impossible or miraculous, now that Zeus, father of the Olympians has made night out of noonday, hiding the bright sunlight, and... fear has come upon mankind. After this, men can believe anything, expect anything. Don't any of you be surprised in future if land beasts change places with dolphins and go to live in their salty pastures, and get to like the sounding waves of the sea more than the land, while the dolphins prefer the mountains." May refer to a total solar eclipse of 6 April 648 BC. Archilochus, Greek poet (c BC) Quoted in Historical Eclipses and Earth's Rotation, by F Richard Stephenson, Cambridge University Press, 1997, page 338. Partly quoted in Encyclopaedia Britannica CD 98. ECLIPSE QUOTES

Eclipses The Sun and Moon occasionally line up perfectly Although the Sun is about 400 times larger than the Moon, it is also about 400 times further away. As a result of this coincidence, the Moon can completely cover the Sun, producing an eclipse

The shadow of any body consists of two parts: The umbra is where the Sun is completely blocked from view. The penumbra is where the Sun is only partially blocked.

Moon's shadow on Earth taken by French cosmonaut Jean-Pierre Haigneré aboard the Mir

When the moon passes through Earth’s shadow.

Three types of Lunar Eclipses Penumbral lunar eclipse—the Moon only passes through the penumbra of Earth’s shadow Partial lunar eclipse—part of the Moon passes through the umbra of Earth’s shadow Total lunar eclipse—the entire Moon passes through the umbra of Earth’s shadow Who on Earth will be able to see a lunar eclipse? Anyone who can see the Moon (anyone who is on the nighttime side of the Earth during the eclipse)

Images from Fred Espenak

Why is the Moon red during an eclipse? The Earth’s atmosphere filters some sunlight and allows it to reach the Moon’s surface The blue light is removed—scattered down to make a blue sky over those in daytime Remaining light is red or orange Some of this remaining light is bent or refracted so that a small fraction of it reaches the Moon Exact appearance depends on dust and clouds in the Earth’s atmosphere

Solar Eclipses When the Moon’s shadow covers part of the Earth Only happens at New Moon Three types: Annular, Partial, and Total

Total Solar Eclipse Observers in the “umbra” shadow see a total eclipse (safe to view the Sun); can see the corona Those in “penumbra” see a partial eclipse—not safe to look directly at Sun Only lasts a few minutes Path of Totality about 10,000 miles long, only 100 miles wide

Photo of a Total Eclipse

Annular Solar Eclipse When the Moon is too far to completely cover the Sun—the umbra doesn’t reach the Earth Sun appears as a donut around the Moon

Photos of an Annular Eclipse photos taken by Fred Espenak

Upcoming Eclipses Will we observe these events? Partial Lunar Eclipse: 2009 Dec 31 A little bit…Partial Lunar Eclipse: 2009 Dec 31 Annular Solar Eclipse: 2010 Jan 15 No!Annular Solar Eclipse: 2010 Jan 15 Partial Lunar Eclipse: 2010 Jun 26 Yes!Partial Lunar Eclipse: 2010 Jun 26 Total Solar Eclipse: 2010 Jul 11 No!Total Solar Eclipse: 2010 Jul 11 Total Lunar Eclipse: 2010 Dec 21 Yes!!Total Lunar Eclipse: 2010 Dec 21 Next Total Solar Eclipse in USA—August 21, 2017 Next Total Solar Eclipse in USA visible in Vermont… April 8 th, 2024!! Mark your calendars!