From the May 2003 issue

Getting the best view of Mars

Here is the equipment you'll need to see details on the Red Planet's surface.
By | Published: May 7, 2003 | Last updated on May 18, 2023
Pathfinder Landing Site
Dark sand dunes that surround the polar cap merge into a large, dark region called Acidalia Planitia. This area, is composed of dark, sand-sized grains of pulverized volcanic rock. Below and to the left of Acidalia are the massive martian canyon systems of Valles Marineris. Early morning clouds can be seen along the left limb of the planet, and a large cyclonic storm composed of water ice, is churning near the polar cap.
Steve Lee / Jim Bell / Mike Wolff / STScI / JPL / NASA
This image of Mars is centered on the region of the planet known as Tharsis. The bright, ring-like feature just to the left of center is the volcano, Olympus Mons. This monster is more than 340 miles (550 kilometers) across and 17 miles (27 kilometers) high. Thick deposits of fine-grained, windblown dust cover most of this hemisphere. The colors indicate the dust is heavily oxidized or “rusted.”
Steve Lee / Jim Bell / Mike Wolff / STScI / JPL / NASA
Syrtis Hemisphere
Prominent features in this hemisphere include Syrtis Major Planitia, the large dark feature seen just below the center of the disk. The giant impact basin Hellas (near the bottom of the disk) is shrouded in bright water-ice clouds. Water-ice clouds also cover several great volcanos in the Elysium region near the eastern edge of the planet (right). A diffuse water-ice haze covers much of the martian equatorial region as well.
Steve Lee / Jim Bell / Mike Wolff / STScI / JPL / NASA
Elysium Planitia
This image is centered near the volcanic region called Elysium Planitia. The area has many small, dark markings that appear to change as a result of sand and dust movements across the planet’s surface. In the upper left, at high northern latitudes, a large chevron-shaped area of water-ice clouds marks a storm front. Along the right limb, a large cloud system has formed around the Olympus Mons volcano.
Steve Lee / Jim Bell / Mike Wolff / STScI / JPL / NASA

To find the best magnification for the Red Planet on a given night, start with a low-power eyepiece and then increase the magnification to roughly 20 to 25 times the telescope’s aperture in inches. (For example, shoot for about 160x if you use an 8-inch telescope). This should give you a crisp view with enough magnification to see plenty of detail. Continue trying successively higher-power eyepieces until increasing the magnification shows no more detail. Back off to the previous eyepiece and you should have an aesthetically pleasing view with as much detail as your telescope and the night’s conditions allow.

The best optics in the world won’t do much good if you have to battle a lot of turbulence in Earth’s atmosphere. A nice steady atmosphere, what observers commonly refer to as “good seeing,” is just as important for getting sharp views — particularly when Mars rides low in the sky and its light has to pass through more air than normal.

Although you might think that the state of the atmosphere lies well beyond your control, that’s only partially true. If you observe Mars when it’s at its highest, you won’t be looking through as much of the atmosphere. You can also improve the local seeing significantly by choosing an observing site in an open grassy area or looking over a large body of water. Avoid obvious heat sources, such as concrete buildings and asphalt parking lots, that soak up the sun’s heat during the day and release it at night. Letting your telescope cool down to the ambient air temperature for 30 to 60 minutes before observing will also help.

Finally, experienced Mars observers swear by a good set of color filters. An orange (Wratten #21 or #23A) filter or a red (#25 or #29) filter works best for showing the ubiquitous dark surface markings. These filters brighten the orange-red deserts and darken the markings, enhancing contrast in the process. Green (#56, #57, and #58) and blue (#38, #38A, or #80A) filters will emphasize the polar caps and bring out any fog, haze, or clouds in the planet’s thin atmosphere.

No other features on Mars stand out like the polar caps. Consisting of water ice and frozen carbon dioxide (dry ice), the caps glow bright white and appear conspicuous whenever they face Earth. Even a small telescope will let you see them wax and wane with the planet’s changing seasons.

Mars experiences seasons much like those on Earth because its axis tilts 25&mdeg; to the plane of its orbit around the sun, just 2&mdeg; more than the tilt of Earth’s axis. The only major differences: Martian seasons last nearly twice as long as those on Earth because the planet’s year equals nearly two Earth years, and seasons in the southern hemisphere of Mars are more severe because the planet always lies farther from the sun when it’s winter in the south and closer to the sun when it’s summer.