Brian Sheen, Director of Cornwall Sea to Stars and the Roseland Observatory, gives an introduction to Mars and the Mars Atlas.
When the ancients looked to the sky they observed all the stars and soon grouped them into constellations and gave them names of animals and gods – many of which we use today. However some of these “stars” refused to stay put and were known as “Wandering Stars”. Mars was a member of this “Awkward Squad” with very strange movements as it crossed the sky.
However all the planets and the Sun and Moon (more or less) follow a track across the sky which we call the ecliptic. The Moon, of course, moves very quickly from West to East following this track over a lunar month. In the course of this movement it passes close to the planets and indeed the Sun giving eclipses. The Moon and all the planets shine by reflecting the light of Sun falling upon them.
The stars and planets rise in the East and set in the West. The Earth rotates on its axis not in twenty four hours but twenty three hours fifty six minutes. This results in the stars rising four minutes earlier every day by our clocks. The whole Solar System orbits the Sun from West to East. Because of this movement Mars can beseen close to the western horizon for a good while after it should have vanished from view.
A recent good example planetary movement was in 2020/21. Jupiter was seen leading Saturn across the sky. As the weeks went by Jupiter closed with Saturn until by Christmas both planets could be seen in a low power telescope at the same time. The reason for these relativemovements is that Jupiter orbits the Sun in a shorter time than Saturn. In 2021 Saturn led Jupiter across the sky with Jupiter falling further and further behind the ringed planet!
When you turn a good telescope on Mars Polar ice caps can be seen and dark patches. These are not vegetation but craters, mountains and valleys as well as volcanoes. These are well shown in the Mars Atlas.
Because the various markings change from time to time and some astronomers thought they could see channels on the surface, the search for life on the planet has been ongoing from the first landers. Viking in 1976 was the first to detect something unusual in tests it carried out. However it was agreed that the strange results were due to inorganic reactions. However as time has gone on and it is now generally agreed that Mars was very much wetter and warmer in the past making it more likely that simple life could have existed many years ago on the planet.