Solar Eclipses Through Space and Time Cycles in the Sky Lou Mayo, NASA/GSFC Chinese astrologers wrote of an eclipse occurring over 4000 years ago. Historians and astronomers believe that this was an eclipse that happened on 22 October 2134 B.C.
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Cycles in the Sky
Lou Mayo, NASA/GSFC
Historians and astronomers believe that this was an eclipse that happened on 22 October 2134 B.C.
Two astrologers at the time, Hsi and Ho, had apparently failed to predict this eclipse, and so were beheaded.
"Nothing can be sworn impossible since Zeus made night during mid-day, hiding the light of the shining Sun."
- Archilochus 648 BC
Norse mythology: the wolflike giant Sköll follows the Sun hoping to devour it.
Ancient Egypt: the evil god Set was thought to have leapt into the eye of the Sun god, Horus.
Ancient China: A heavenly dog ate the Sun.
Chippewa Indians shot flaming arrows at the Sun hoping to rekindle the flames.
(32.7’ to 31.6’)
(33.5’ to 29.4’)
August 16, 1868: Helium is discovered in solar corona.
May 29, 1919: General relativity is verified
Total solar eclipses provide opportunity to study composition of corona.
Accurate timings allow calculation of solar dimensions.
Studies of ancient records reveal 0.001s slowing of Earth’s rotation
Oh leave the Wise our measures to collateOne thing at least is certain, LIGHT has WEIGHTOne thing is certain, and the rest debate --Light-rays, when near the Sun, DO NOT GO STRAIGHT.- Arthur S. Eddington (1920)
August 11, 1999
HD 209458 (mv = +7.7) in Pegasus
GOALS: To simulate a solar eclipse To understand the concept of angular size To make estimates of absolute and
MATERIALS: Yard or meter stick (don't
confuse your units!) Construction paper Tape Scissors CD-ROM Pencil Black and yellow markers
1. MAKE THE SUN: Lay the CD on the construction paper and trace around its outer edge. Then trace around the center hole.
2. Draw two lines (a tab) down from the CD and fanning out so the CD circle and tab look like the picture on this slide. The tab will be used to mount the CD circle on the yard/meter stick.
3. Cut out the large CD circle and connected tab. This will represent the sun. The small circle in the center will represent the size of the moon (of course, this is not to scale).
4. Color the CD circle yellow (for the sun) and the small center circle black.
5. MAKE THE MOON: Now, on a different piece of construction paper, trace just the center hole in the CD. Make the same kind of tab for this circle as you did for the sun circle. Make the tab a bit longer than the sun's tab. Color the moon black and cut it out.
6. ASSEMBLE: Bend the sun and moon back 90 degrees from their tabs at the BASE of the tab. Wrap the fanned out portion of the tabs around the yard/meter stick and tape the ends together. The sun should be near the end of the stick and the moon should be near the front. The sun and moon should now be able to slide up and down the stick.
Looking at the yard/meter stick, note the distance (in inches or cm) of the moon. Then note the distance of the sun. Finally, measure the diameter of the moon. You can now create similar triangles that will help you answer the following questions: