WHAT TO LOOK FOR The most prominent dark markings to look for are Syrtis Major, Mare Acidalium, Utopia, Mare Erythraem and Sinus Sabeus. These markings vary from year to year and may even show changes during the next two months. More transient features are the clouds that come and go. They appear as white spots that often cover the same areas at the same time of the martian day. With larger instruments it is possible to see the clouds that often top the great martian volcanoes in Tharsis.
Dust storms can also come and go.
They appear as yellowish clouds that start out small, yet may possibly grow to encompass the entire planet. There is no way to predict when or where these dust storms will appear. Because the martian day is only 40 minutes longer than the earth's, you will be presented with the same side of mars observed at the same time on successive nights. If you observe every night at 1 AM, for instance, it will take over 40 nights to see the entire planet slowly rotate into view. See mars features to identify these features in your telescope.