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Observing Mars through a telescope

Mars is the fourth planet from the Sun. It is also known as the "Red Planet", for its orange-red appearance.

What Mars is

Mars is the fourth planet from the Sun. It is also known as the "Red Planet", for its orange-red appearance. Mars is a desert-like rocky planet with a tenuous atmosphere that is primarily carbon dioxide. At the average surface level the atmospheric pressure is a few thousandths of Earth's, atmospheric temperature ranges from −153 to 20 °C, and cosmic radiation is high. Mars retains some water, in the ground as well as thinly in the atmosphere, forming cirrus clouds, fog, frost, larger polar regions of permafrost and ice caps, but no bodies of liquid surface water. Its surface gravity is roughly a third of Earth's or double that of the Moon. Its mean diameter, 6,779 km (4,212 mi), is about half the Earth's, or twice the Moon's, and its surface area is the size of all the dry land of Earth.

Observing Mars through a telescope

Mars is small and only shows detail near its close approaches every two years, when a telescope of 100 mm or more can reveal dark markings and a polar cap. High, steady magnification and patience are needed.

Planets and the Moon reward higher magnification than deep-sky objects, but only up to what the air will allow: on a turbulent night the image boils and less power shows more. Magnification is your telescope's focal length divided by your eyepiece's focal length, so a shorter eyepiece gives more power. Use the Fit My Telescope tool to see the magnification and exit pupil each of your eyepieces gives before you observe.

Mars in NASA imagery

NASA has imaged Mars in detail. One example in the NASA Image and Video Library is titled Composite image of the planet Mars taken by Hubble Space Telescope (HST), from JSC. NASA imagery is in the public domain.

Related

Sources: Mars (Wikipedia, CC BY-SA) · Wikidata (CC0) · NASA Image and Video Library: S91-32389 (public domain)