Observing Mars

The visibility of Mars is quite variable as it and the Earth go through their cycles. The orbit of Mars is the next beyond the Earth's, so when both planets are on the same side of the Sun, Mars is near, brighter, and bigger in a telescope. When an outer planet like Mars is lined up with the Sun and the Earth, beyond the Earth, it is said to be at opposition. The planet is then closest, and high in the midnight sky. After the Earth passes Mars in its orbit, Mars gets much further away, and is smaller and dimmer.

So the best time to look at Mars is near the opposition time, but, because the orbit of Mars is very elliptical, some oppositions are more favorable that others.

As you see from the diagram, the 1999 opposition is not a particularly favorable one, and the next really favorable oppositions are in 2003 and 2005

Viewing through a telescope near a favorable opposition, it is fairly easy to see the polar caps of Mars, and some dark areas on the disk of the planet. At other times, even at oppositions that are unfavorable, the planet is likely to look like a small red dot in the telescope. Wait for very good seeing (quiet atmosphere), and try high power on your scope, and you may be able to see a polar cap.

The next opposition of Mars is April 24, 1999.
To the naked eye, Mars is distinctly red and, near opposition, as bright as all but one or two of the very brightest stars. At a favorable opposition Mars is stunningly bright and red, outshining all the stars, and even Jupiter sometimes. Away from opposition, Mars fades to second magnitude, and becomes the dimmest of the five planets known to the ancients.

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