These color and black and white pictures of Mars were taken by NASA's Hubble Space Telescope just two weeks after Earth made its closest approach to the Red Planet during the 1997 opposition. When the Hubble pictures were taken Mars was at a distance of 62 million miles (100 million kilometers) and the resolution at the center of the disk is 13.5 miles/pixel (22 kilometers/pixel). Both images were made with the Wide Field and Planetary Camera 2. The color composite (left image) is constructed from three images taken in red (673 nanometers), green (502 nm) and blue (410 nm) light. The right image, in blue light only, brings out details in the cloud structure and is remarkably similar to weather satellite pictures taken of Earth. A planetary-scale wave curls around the north pole, similar in behavior to high latitude cold fronts which descend over North America and Europe during springtime.
The picture was taken when Mars was near aphelion, its farthest point from the Sun. The faint sunlight results in cold atmospheric conditions which stimulate the formation of water ice clouds. The clouds themselves further reduce atmospheric temperatures. Atmospheric heating, resulting when sunlight is absorbed by the dust, is reduced when ice forms around the dust particles and causes the dust to gravitationally settle to the ground.
These images of Mars are centered at approximately 94 degrees longitude and 23 degrees N latitude (oriented with north up). The four largest Tharsis Montes (massive extinct volcanoes) are visible as dark spots extending through the clouds. The vast canyon system, Valles Marineris, stretches across the eastern (lower right) half of the image; the Pathfinder landing site is near the eastern edge of the image.
It is early summer in the northern hemisphere, and the North polar cap has retreated to about 80 degrees N latitude; the "residual" summer cap, which is composed of water ice, is about one-third the size of the "seasonal" winter cap, which consists mostly of carbon-dioxide frost (dry ice) condensed on the surface. The polar cap is surrounded by a "sand sea" made up of dark sand dunes. A distinct belt of water-ice clouds extends over much of this hemisphere.
Credits
Phil James (Univ. Toledo), Todd Clancy (Space Science Inst., Boulder, CO), Steve Lee (Univ. Colorado), and NASA| About The Object | |
|---|---|
| Object Name | Mars |
| Object Description | Planet |
| Distance | At the 1997 Mars opposition, the planet was approximately 62 million miles (100 million kilometers) from Earth. |
| Dimensions | The planet has a diameter of 4,222 miles (6,794 km) at the equator. |
| About The Data | |
| Instrument | HST>WFPC2 |
| Exposure Dates | March 1997 |
| Filters | 410 nm, 502 nm, and 673 nm |
| About The Image | |
| Color Info | Color image Blue: 410 n nanometers Green: 502 nanometers Red: 673 nanometers Grayscale image Blue: 410 n nanometers |
| About The Object | |
|---|---|
| Object Name | A name or catalog number that astronomers use to identify an astronomical object. |
| Object Description | The type of astronomical object. |
| R.A. Position | Right ascension – analogous to longitude – is one component of an object's position. |
| Dec. Position | Declination – analogous to latitude – is one component of an object's position. |
| Constellation | One of 88 recognized regions of the celestial sphere in which the object appears. |
| Distance | The physical distance from Earth to the astronomical object. Distances within our solar system are usually measured in Astronomical Units (AU). Distances between stars are usually measured in light-years. Interstellar distances can also be measured in parsecs. |
| Dimensions | The physical size of the object or the apparent angle it subtends on the sky. |
| About The Data | |
| Data Description |
|
| Instrument | The science instrument used to produce the data. |
| Exposure Dates | The date(s) that the telescope made its observations and the total exposure time. |
| Filters | The camera filters that were used in the science observations. |
| About The Image | |
| Image Credit | The primary individuals and institutions responsible for the content. |
| Publication Date | The date and time the release content became public. |
| Color Info | A brief description of the methods used to convert telescope data into the color image being presented. |
| Orientation | The rotation of the image on the sky with respect to the north pole of the celestial sphere. |
