A thin crescent moon appears low in the southwestern sky Friday night. You only have a few minutes to enjoy it, as it will soon set. The moon is in the zodiacal constellation Taurus, not far from the star cluster Pleiades. Best of all, the moon is a short distance away from the red planet Mars.

We are losing Mars. Mars has been with us in the evening sky for a year. A year ago, the planet was brilliant in the evening sky and not difficult to find. Friday night, Mars is low in the western sky and in the span of an hour, it sets with the westward movement of the stars. Mars is not as easy to see, but it still has that distinct reddish tint.

We have less than two more months of Mars in our evening sky, before it shifts to becoming a morning planet late in the summer.

Mars is the one planet in our sky which varies the most in brilliance. Brightness is tied to the fact that the planet varies so much in distance from the Earth, and it is also a small planet. Mars is about 213 million miles away this week, more than twice the distance from us as the sun. Last summer Mars got as close as 46 million miles from us.

Next year Mars gets even closer. The planet will be in opposition in July 2018 and it will be only 36 million miles away.