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Дата изменения: Unknown Дата индексирования: Sat Dec 22 01:32:30 2007 Кодировка: Поисковые слова: moon |
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Astronomy Picture of the Day |
APOD: 2002 November 24 - Hubble Floats Free
Explanation:
Why put observatories in space?
Most telescopes are on the ground.
On the ground, you can deploy a heavier telescope
and fix it more easily.
The trouble is that
Earth-bound telescopes
must look through the Earth's atmosphere.
First, the Earth's atmosphere
blocks out a broad range of the
electromagnetic spectrum, allowing
a narrow band of visible light to reach the surface.
Telescopes which explore the Universe using light
beyond the visible spectrum, such as those onboard the
Chandra X-ray Observatory
need to be carried above the absorbing atmosphere.
Second, the Earth's atmosphere blurs the light
it lets through.
The blurring is caused by varying density and
continual motion of air.
By orbiting above the Earth's atmosphere,
the Hubble Space Telescope,
pictured above,
can get clearer images.
In fact, even though HST
has a mirror 15 times smaller than large Earth-bound telescopes,
it can still resolve finer details.
A future large
optical telescope in space is
planned.
APOD: 2000 January 16 - The Compton Gamma Ray Observatory
Explanation:
The
Compton Gamma Ray Observatory (CGRO) was the
most massive instrument ever launched by a
NASA Space Shuttle in 1991
and continues to revolutionize
gamma-ray astronomy.
Before Compton loses more stabilizing gyroscopes,
NASA is considering firing onboard rockets to
bring it on a controlled reentry into the ocean.
This orbiting observatory sees the sky in
gamma-ray photons - light so blue humans can't see it.
These photons are blocked by the Earth's atmosphere
from reaching the Earth's surface.
Results from CGRO,
pictured above, have shown the
entire universe to be a violent and rapidly changing place -
when viewed in gamma-rays.
Astronomers using
CGRO data continue to make
monumental discoveries, including identifying
mysterious gamma-ray bursts that uniquely illuminate
the early universe, discovery of a whole new class of QSOs,
and discovery of objects so strange that astronomers
can't yet figure out what they are.
APOD: 199 July 27 - Chandra X Ray Telescope
Explanation:
Wrapped in protective blankets and mounted atop an
Inertial Upper Stage (IUS) rocket,
the Chandra X-ray Telescope is
seen in this wide-angle view
before launch snuggled into the
space shuttle Columbia's payload bay.
Columbia's crew released
the telescope, named in honor of the late Nobel Laureate
Subrahmanyan Chandrasekhar,
into orbit on Friday, July 23rd,
where it is now undergoing check out and
activation of its scientific instruments.
To help realize its enormous potential for
exploration of the distant Universe at
X-ray energies, controllers
will perform a series
of firings in the coming days
which will eventually
boost the 10,000 pound telescope into a highly ecentric orbit.
In fact, the final working orbit for Chandra
will range from a close point of about 6,200 miles out
to 87,000 miles or one third of
the distance to the Moon.
The elongated orbit will carry Chandra's
sensitive
X-ray detectors beyond interference caused
by the Earth's
radiation belts allowing Chandra to make about 55 hours
of continuous observations per orbit.
The shuttle Colombia, commanded by
Eileen Collins is
scheduled to land this evening at
11:20 pm EDT at Kennedy Space Center.
Authors & editors:
Robert Nemiroff
(MTU) &
Jerry Bonnell
(USRA)
NASA Web Site Statements, Warnings, and
Disclaimers
NASA Official: Jay Norris.
Specific rights apply.
A service of:
EUD at
NASA /
GSFC
& Michigan Tech. U.