Astronomy Picture of the Day Index - Solar System: Earth's Moon

APOD: 1999 November 8 - Lunation
Explanation: Our Moon's appearance changes nightly. This slow-loading time-lapse sequence shows what our Moon looks like during a lunation, a complete lunar cycle. As the Moon orbits the Earth, the half illuminated by the Sun first becomes increasingly visible, then decreasingly visible. The Moon always keeps the same face toward the Earth. The Moon's apparent size changes slightly, though, and a slight wobble called a libration is discernable as it progresses along its elliptical orbit. During the cycle, sunlight reflects from the Moon at different angles, and so illuminates different features differently. A full lunation takes about 29.5 days, just under a month (moon-th).

APOD: 1996 September 26 - Tonight: A Total Lunar Eclipse
Explanation: Tonight brings the last total lunar eclipse visible from North America until the year 2000 - with the Moon becoming completely immersed in Earth's shadow. The above time- lapse photograph shows a lunar eclipse that occurred in April 1993. Tonight's eclipse will begin at 8:12 pm Eastern Daylight Time, with totality extending from 10:19 pm to 11:29 pm. In North and South America, the Moon will be just rising at the beginning of the eclipse. In West Europe and Africa, tonight's lunar eclipse will be visible before the dawn of September 27^th. The Moon is not expected to become completely dark - usually it has a slight red glow caused by sunlight refracted through the Earth's dusty atmosphere - but every lunar eclipse is slightly different. This year's eclipse will be enhanced by the proximity of bright Saturn just 3 degrees away.

APOD: 1998 May 3 - Standing on the Moon
Explanation: Humans once walked on the Moon. Pictured above is the second person to stand on the lunar surface: Edwin "Buzz" Aldrin. During this Apollo 11 mission, Neil Armstrong (the first person to walk on the moon) and Buzz Aldrin landed on the Moon while Michael Collins circled in the Command Module above. The lunar team erected a plaque on the surface that reads: HERE MEN FROM THE PLANET EARTH FIRST SET FOOT UPON THE MOON JULY 1969 A.D. WE CAME IN PEACE FOR ALL MANKIND. The Apollo missions demonstrated that it is possible to land humans on the Moon and return them safely.