NASA Great Images in Nasa Collection

Mars and Syrtis Major

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.

06/30/1999

Hubble Space Telescope Center

Planetary Astronomy

Planet-Mars

Hubble

Space

Field

Camera

Viking

Mars

Telescope

Wide

Planetary

Hubble

HST

Major

WFPC

Olympus

Mons

Elysium

Syrtis

Acidalia

Tharsis

General Public

Camera 2

Earth

Sun

Crater

Surveyor

Polar

Mars

Viking

Huygens Probe

Deep Impact

Hubble Space Telescope (HST)

Mars Global Surveyor Orbiter (MGS)

Mars

Colorado

17th century

06-30-1999

1999

PR99-27D

http://grin.hq.nasa…

SPD-GRIN-GPN-2000-00 0923

HSTI

PR99-27D

GPN-2000-000923

NASA, Steve Lee University of Colorado, Jim Bell Cornell University,

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