NASA Center: |
Hubble Space Telescope Center |
Image # : |
PR99-27D |
Date : |
06/30/1999
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Title
Mars and Syrtis Major
Full Description
Taking advantage of Mars's closest approach to Earth in eight years,
astronomers using NASA's Hubble Space Telescope have taken the space-
based observatory's sharpest views yet of the Red Planet.
The telescope's Wide Field and Planetary Camera 2 snapped these images
between April 27 and May 6, when Mars was 54 million miles (87 million
kilometers) from Earth. From this distance the telescope could see
Martian features as small as 12 miles (19 kilometers) wide.
The telescope obtained four images, which, together, show the entire
planet. Each view depicts the planet as it completes one quarter of its
daily rotation. In these views the north polar cap is tilted toward the
Earth and is visible prominently at the top of each picture. The images
were taken in the middle of the Martian northern summer, when the polar
cap had shrunk to its smallest size. During this season the Sun shines
continuously on the polar cap. Previous telescopic and spacecraft
observations have shown that this summertime "residual" polar cap is
composed of water ice, just like Earth's polar caps.
These Hubble telescope snapshots reveal that substantial changes in the
bright and dark markings on Mars have occurred in the 20 years since
the NASA Viking spacecraft missions first mapped the planet. The
Martian surface is dynamic and ever changing. Some regions that were
dark 20 years ago are now bright red; some areas that were bright red
are now dark. Winds move sand and dust from region to region, often in
spectacular dust storms. Over long timescales many of the larger bright
and dark markings remain stable, but smaller details come and go as
they are covered and then uncovered by sand and dust.
The dark feature known as Syrtis Major was first seen telescopically by
the astronomer Christiaan Huygens in the 17th century. Many small,
dark, circular impact craters can be seen in this region, attesting to
the Hubble telescope's ability to reveal fine detail on the planet's
surface. To the south of Syrtis is a large circular feature called
Hellas.
Viking and more recently Mars Global Surveyor have revealed that Hellas
is a large and deep impact crater. These Hubble telescope pictures show
it to be filled with surface frost and water ice clouds. Along the
right limb, late afternoon clouds have formed around the volcano
Elysium.
Keywords
Hubble Space Telescope HST Mars Syrtis Major Viking Wide Field Planetary Camera WFPC Olympus Mons Elysium Syrtis Major Acidalia Tharsis
Subject Category
Planet-Mars, Hubble, Planetary Astronomy,
Reference Numbers
- Center:
HSTI
- Center Number:
PR99-27D
- GRIN DataBase Number:
GPN-2000-000923
Source Information
- Creator/Photographer: NASA, Steve Lee University of Colorado, Jim Bell Cornell University,
- Original Source: DIGITAL
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Updated October 31, 2002
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