Volcanoes 101 . Site map . 07.26.99 Early Wednesday morning, July 28, will be your last chance this millennium to see a lunar eclipse . A lunar eclipse occurs when Earth blocks the light from the Sun that normally makes the Moon visible by reflection. Wednesday's event will be what astronomers call a partial eclipse, because only part of the Moon will pass through the full shadow cast by our home planet.
Earth blocks the Sun in a cone-shaped shadow called an umbra.
The penumbra is an area where Earth blocks some of the Sun's rays. The best seats In the United States and the rest of the Americas, west coast residents will have the best view, astronomers say. In eastern North and South America, only the beginning of the event will be visible before sunrise. The eclipse will also be visible in Australia, New Zealand, and much of East Asia and the Pacific, where it occurs Wednesday evening. Astronomers say the Moon may take on an eerie orange or red glow as some of the Sun's light is scattered through Earth's atmosphere, with only certain wavelengths of light reaching the Moon.