dipper@utastro.UUCP (Debbie Byrd) (05/04/85)
If you lived on the moon, you'd see the Earth eclipse the sun today. More -- after this. May 4 A Lunar Eclipse Observers on the opposite side of the globe from North America will see a total eclipse of the moon today -- an event during which the moon passes through the shadow cast by its larger sister world -- our Earth. At mid-eclipse, the moon will appear coppery red in the shadow of the Earth. From the Earth, we see an eclipse of the moon -- but today any beings that happened to BE on the moon would see an eclipse of the sun. They'd see the Earth pass in front of the sun -- blocking its light from their view. The sun is much farther away than the moon -- but we on Earth see both the sun and moon appear nearly the same size on the dome of our sky. It's just lucky geometry. The moon is about 400 times smaller than the sun -- but the sun is about 400 times farther away. On the other hand, from the moon, the disk of the Earth appears about twelve times the size of the sun's disk. An eclipse of the sun by the Earth -- seen from the moon -- would last longer. What's more -- during an eclipse of the sun by the Earth, beings on the moon would see Earth's atmosphere stand out around our world as a many-colored silhouette. The colors are produced when the air around Earth acts like a prism to split the sun's light. Such a thing has been seen only once by earthlings -- when astronauts coming back from the moon in 1969 actually saw an eclipse of the sun by the Earth. Script by Diana Hadley and Deborah Byrd. (c) Copyright 1984, 1985 McDonald Observatory, University of Texas at Austin