Educator's Guide to Eclipses . ... In a solar eclipse you observe the Sun (using only safe methods, of course). ... In a lunar eclipse you observe the Moon. ... Because of the geometry described below, you can only view a solar eclipse when the Sun is up, and the Moon is nowhere to be seen. ... Eclipses occur when the Sun, Earth and Moon line up. ... In a solar eclipse the Moon passes directly in front of the Sun. ... In a lunar eclipse the Moon moves into Earth's shadow. ...

This section describes the calculation by which Aristarchus used the duration of a total lunar eclipse to deduce the distance of the Moon. ... This lesson plan supplements: "How Distant is the Moon--1", section #8c: on disk Shipprc2.htm , on the web . ... The shadow of the Earth at the Moon's distance is narrower than the Earth, because the Sun is seen not as a point but as a disk 0.5 degrees wide. ... An eclipse of the Moon is the passage of the Moon through the shadow of the Earth. ...

small image in visible light 10k gif . ... A huge eruptive prominence leaving the sun 261k gif ; 203k jpg ; 6000k tiff . ... X-ray image of the Sun 172k gif . ... radio images of the Sun 140k gif . sun hydrogen alpha image 149k gif ; 34k jpg . Solar flare in H-alpha 147k gif ; 38k jpg . ... July 91 eclipse by Steve Albers ( caption ) 431k gif ; 143k jpg . ... Current solar images (updated daily) html ; html . eclipse images and movies ftp dir ; html from Goddard; html from Bernie Verreau . ...