Astronomy Picture of the Day |
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 27th.
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.
Authors & editors:
Robert
Nemiroff
(MTU)
& Jerry Bonnell (USRA)
NASA Technical Rep.:
Jay Norris.
Specific rights apply.
A service of:
LHEA at
NASA/
GSFC
&
Michigan Tech. U.