This powerpoint compiled by the Education Staff at the Lunar and Planetary Institute www.lpi.usra.edu Image from http://solarsystem.nasa.gov/multimedia/gallery/Earth_Moon.jpg This picture of the Earth and Moon in a single frame, the first of its kind ever taken by a spacecraft, was recorded September 18, 1977, by NASAs Voyager 1 when it was 11.66 million km (7.25 million miles) from Earth. The moon is at the top of the picture and beyond the Earth as viewed by Voyager. In the picture are eastern Asia, the western Pacific Ocean and part of the Arctic. Voyager 1 was directly above Mt. Everest (on the night side of the planet at 25 degrees north latitude) when the picture was taken.
Total Solar Eclipse showing the corona and a few prominences off the limb (in red). When the moon blocks the light from the bright solar photosphere, we can see the much dimmer, more subtle evidence of the corona.
Only after phases have been mastered should you try to teach the reason for eclipses; otherwise, students will often assume that the reason for the Moon’s phases is the Earth’s shadow. To understand why we have eclipses, we use the golfballs and blacklights, along with an embroidery hoop to model out the changing intersection of the Moon’s orbit with the ecliptic, as the Earth goes around the Sun.
Shadow of the moon on the Earth as observed from the MIR space station.
Diagram from Fred Espenak, may be found along with lots of good information at http://www.mreclipse.com/Special/SEprimer.html
Diagram by Fred Espenak and more information may be found at www.MrEclipse.com
This graphic shows the path of totality for different solar eclipses through 2025. Notice there are two solar eclipses that cross the United States (2017 and 2024).
Diagram from Fred Espenak, may be found along with information at http://www.mreclipse.com/Special/SEprimer.html
From http://sunearthday.nasa.gov/2006/multimedia/gal_010.php; photos taken by Fred Espenak
http://www.mreclipse.com/Special/LEprimer.html Additional details are at http://en.wikipedia.org/wiki/Lunar_eclipse
Images from Fred Espanak and may be found at http://www.mreclipse.com/LEphoto/LEgallery1/LEgallery1.html
Information at http://sunearth.gsfc.nasa.gov/eclipse/solar.html
Transcript of "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 (c680-640 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 <ul><li>The Sun and Moon occasionally line up perfectly </li></ul><ul><li>Although the Sun is about 400 times </li></ul><ul><ul><li>larger than the Moon, it is also about </li></ul></ul><ul><ul><li>400 times further away. </li></ul></ul><ul><ul><li>As a result of this coincidence, the Moon can completely cover the Sun, producing an eclipse </li></ul></ul>
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
Solar Eclipses <ul><li>When the Moon’s shadow covers part of the Earth </li></ul><ul><li>Only happens at New Moon </li></ul><ul><li>Three types: Annular , Partial , and Total </li></ul>
Solar Eclipse Factoids <ul><li>Under the most favorable conditions, the </li></ul><ul><li>diameter of the shadow (umbra) is only 269 km wide (155 miles). </li></ul><ul><li>At the equator, the shadow moves at 1730 km/hr . </li></ul><ul><li>Totality can last as long as 7½ minutes . </li></ul><ul><li>A total solar eclipse occurs about once every </li></ul><ul><li>18 months somewhere in the world . </li></ul><ul><li>At any given location, a total solar eclipse </li></ul><ul><li>occurs once every 360 years . </li></ul><ul><li>Sun’s corona is visible. </li></ul>
Total Solar Eclipse <ul><li>Observers in the umbra shadow see a total eclipse (safe to view the Sun) </li></ul><ul><li>Those in penumbra see a partial eclipse—not safe to look directly at Sun </li></ul>
Frequency of Solar Eclipses <ul><li>We do not get solar eclipses at every new </li></ul><ul><li>moon because the orbit of the Moon is tilted </li></ul><ul><li>by about 5 degrees with respect to the </li></ul><ul><li>ecliptic. </li></ul><ul><li>At most new moons the Moon is either above or </li></ul><ul><li>below the Sun. </li></ul><ul><li>The tilted orbit of the Moon crosses the ecliptic at </li></ul><ul><li>two points. When the Sun approaches these </li></ul><ul><li>points, eclipses are possible. This will happen </li></ul><ul><li>twice a year. </li></ul>
Photo of a Total Eclipse http://sunearthday.nasa.gov/2006/multimedia/gal_008.php
Annular Solar Eclipse <ul><li>When the Moon is too far to completely cover the Sun—the umbra doesn’t reach the Earth (at or near Apogee ) </li></ul><ul><li>Sun appears as a donut around the Moon </li></ul>
Photos of an Annular Eclipse http://sunearthday.nasa.gov/2006/multimedia/gal_010.php; photos taken by Fred Espenak
<ul><ul><li>When the moon passes through Earth’s shadow. </li></ul></ul>
Three types of Lunar Eclipses <ul><li>Penumbral lunar eclipse —the Moon only passes through the penumbra of Earth’s shadow </li></ul><ul><li>Partial lunar eclipse —part of the Moon passes through the umbra of Earth’s shadow </li></ul><ul><li>Total lunar eclipse —the entire Moon passes through the umbra of Earth’s shadow </li></ul><ul><li>Who on Earth will be able to see a lunar eclipse? </li></ul>Anyone who can see the Moon (anyone who is on the nighttime side of the Earth during the eclipse)
Images from Fred Espenak http://www.mreclipse.com/LEphoto/LEgallery1/LEgallery1.html
Why is the Moon red during an eclipse? <ul><li>The Earth’s atmosphere filters some sunlight and allows it to reach the Moon’s surface </li></ul><ul><li>The blue light is removed—scattered down to make a blue sky over those in daytime </li></ul><ul><li>Remaining light is red or orange </li></ul><ul><li>Some of this remaining light is bent or refracted so that a small fraction of it reaches the Moon </li></ul><ul><li>Exact appearance depends on dust and clouds in the Earth’s atmosphere </li></ul>
Upcoming Eclipses <ul><li>Will we observe these events? </li></ul><ul><li>Full Lunar Eclipse Dec. 10 th , 2011: No </li></ul><ul><li>Annular eclipse of sun May 20: No (West Coast of US will see it) </li></ul><ul><li>Transit of Venus June 5 th /6 th , 2012: Partial View </li></ul><ul><li>2 other lunar eclipses 2012 (June 4, Nov 28): No </li></ul><ul><li>Next Total Solar Eclipse in USA—August 21, 2017 </li></ul><ul><li>Next Total Solar Eclipse in USA visible in Vermont… </li></ul><ul><li>April 8 th , 2024!! Mark your calendars! </li></ul>
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