| Home | Articles | Guide to Observing | Tour of the Constellations | Book Reviews |
No planet has captured the imagination, mystified, fascinated and just plain terrified people like the first superior planet, Mars. Unfortunately, there probably has never been a systematic survey of science fiction movies, but without a doubt, Mars is the most popular place of origin for bugged-eye monster and other friendly creatures from outer space attempting to subjugate the Earth. It seems somehow easier to conjure up a picture of a Martian (green or otherwise) than a denizen of Jupiter, Venus or Pluto.
And of course there are its canals. In a fairly good 1964 film, "Robinson Crusoe On Mars", a stranded American astronaut peers out of an opening in a sheer cliff towards a vast canyon and proclaims that he has discovered the Martian canals. There are no such things. Giovanni Schiaparelli, in 1877, observed what appeared to him to be straight lines on the surface of Mars. He described them as canali, the Italian word for channels, which was promptly mistranslated to canals. Once people hear about the canali or canals, they quickly began to see them for themselves; they also began to fill them with water. Alas, when the first space probes photographed Mars, unhampered either by the Earth’s unsteady atmosphere or people’s overactive imaginations, the canals vanished.
So what does Mars really look like? For one thing, it is very red. I remember the first time I saw Mars. I was taking a quick glance at the evening sky and suddenly noticed this incredibly red star. It wasn't particularly bright, which made it even more extraordinary. Never before had I seen such a comparatively dim star with such a striking color and later I confirmed that it was Mars.
Mars does not pass through phases, but its synodic period is still useful to know. Mars is 1.52 a.u. from the Sun, with a year almost twice as long as our own. It synodic period is 780 days, over two years long. Mars is the first planet which contains details that we are able to see, if we are close enough to it and its synodic period is intimately related to the question of proximity. Once during every synodic period, Mars is in opposition from the Earth. At opposition, the Sun, Earth and mars are on a straight line with the Earth in the middle. Also once every synodic period, Mars and Earth are in conjunction, being also located on a straight line with the Sun in the middle position. When at conjunction, the Earth and Mars are at opposite sides from the Sun and there is a maximum distance between them. Mars will be both dim and small; it will be difficult to see any of its surface details (not the canals, but the real one.) When Mars is at opposition, it is in the middle of its retrograde loop and the distance between the two planets will be relatively small, its disk will appear large and it will have a negative magnitude.
If the orbits of both Mars and Earth were perfect circles, every 780 days Mars would reach the same brightness, but both planets move in an ellipse. For instance, the Earth approaches closest to the Sun on January 2 and it reaches the greater distance from the Sun around July 4. The tilt of the Earth's axis affects the weather far more than its distance from the Sun. The deviation from a perfect orbit is small for the Earth, only about 1,600,00 miles, but greater for Mars, which can approach over 13,000,000 miles closer to the Sun than its average distance. The most favorable time for viewing Mars is at an opposition in which Mars is at a minimal distance from the Sun and Earth. The next favorable opposition of Mars will take place at August 28, 2003 and the planet will have a magnitude of –2.7.
Mars' remarkable color is not steady. At times the planet's color pales to yellow as giant dust storms rage over its surface. Through binoculars during a favorable opposition, it is possible to see the ice caps on the Martian North and South Poles. Thanks to the tilt of Mars' axis, it passes through seasons once every 22-˝ month revolution around the Sun. While it is winter at one pole, it is summer at the other, so that alternatively one white polar cap shrinks as the other expands. Even though one is unable to see any of the hundreds of Martians crater from the Earth, it is possible through binoculars to pick out a dark triangular form called Syrtis Major, which is now known to be a giant depressed plain. The shades of Mars are particularly subtle and the more experience you gather of looking at Mars, the more you will be able to see.
Mars has two small satellites called Phobos and Deimos, which can only be seen through a large telescope.