Astronomy Picture of the Day

Explanation: Yesterday the Sun crossed the celestial equator heading south, marking the Equinox -- the first day of Autumn in the northern hemisphere and Spring in the south. Equinox means equal night and with the Sun on the celestial equator, Earthlings will experience 12 hours of daylight and 12 hours of darkness. For those in the northern hemisphere, the days will continue to grow shorter with the Sun marching lower in the sky as winter approaches. A few weeks after the Autumnal Equinox of 1994, the Crew of the Shuttle Endeavor recorded this image of the Sun poised above the Earth's limb. Glare illuminates Endeavor's vertical tail (pointing toward the Earth) along with radar equipment in the payload bay.