Astronomy Picture of the Day |
APOD: 1999 October 5 - Two Hours Before Neptune
Explanation:
Two hours before closest approach to
Neptune in 1989, the
Voyager 2 robot spacecraft snapped
this picture.
Clearly visible for the first time were long light-colored
cirrus-type clouds floating high in
Neptune's atmosphere. Shadows of these clouds can even
be seen on lower cloud decks.
Most of
Neptune's atmosphere is made of
hydrogen and
helium, which is invisible.
Neptune's blue color therefore comes from
smaller amounts of atmospheric
methane,
which preferentially absorbs red light.
Neptune has the fastest winds in the
Solar System, with gusts reaching 2000 kilometers per hour.
Recent speculation holds that
diamonds may be created in the
dense hot conditions that exist under the clouds-tops of Uranus and Neptune.
APOD: 1998 February 21 - Neptune: Big Blue Giant
Explanation:
This picture was taken by the Voyager 2 spacecraft in 1989 - the only spacecraft
ever to visit Neptune. Neptune will be the furthest planet from the
Sun until 1999, when the
elliptical orbit of
Pluto
will cause it to once again resume this status. Neptune, like Uranus, is composed mostly of liquid water,
methane and ammonia, is surrounded by a thick gas
atmosphere of mostly hydrogen and helium,
and has many moons and rings. Neptune's moon
Triton is unlike any
other and has active volcanoes. The nature of
Triton's unusual orbit around
Neptune
is the focus of much discussion and speculation.
APOD: 1999 October 25 - Neptune in Infrared
Explanation:
Neptune has never looked so clear in
infrared light.
Neptune is the eighth most distant planet from the Sun,
thirty times the Earth-Sun distance.
Neptune is the fourth largest planet,
almost four times Earth's diameter.
Surprisingly, Neptune
radiates about twice as much energy as it receives from the Sun.
A fascinating feature of the above photograph is that it was taken far from distant
Neptune,
through the Earth's normally blurry atmosphere.
The great clarity of this recently released image was made
possible by "rubber mirror"
adaptive optics technology.
Here, mirrors in the new
Palomar High Angular Resolution Observer
(PHARO) instrument connected to the
200-inch Hale Telescope
flex to remove the effects of turbulence in the Earth's atmosphere.
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.