Moon and Companions

A couple of bright orange dots accompany the gibbous Moon across the sky tonight: the planet Mars and the star Aldebaran. Mars is the brighter of the two, and rises close to the lower left of the Moon. Aldebaran is farther to the right of the Moon. They’re all in good view by about 8 o’clock.

Mars and Aldebaran appear orange for different reasons. Mars is “rusty” — it’s covered by dust that contains a lot of iron, which has a dark orange color. Aldebaran is orange because its surface is fairly cool, and cooler gas looks redder than hotter gas.

Mars is about eight times brighter than Aldebaran right now. Aldebaran’s brightness doesn’t really change. The star is so far away that any changes in its distance are insignificant.

But Mars is in our own solar system. It’s the next planet out from the Sun. So over a couple of years, its distance from Earth varies by a wide margin — from a maximum of almost 250 million miles to a minimum of less than 40 million.

Now, Earth and Mars are heading toward one of those close encounters. On December 1st, they’ll pass about 50 million miles apart. And as Mars gets closer, it gets brighter. At its brightest, the only objects in view in the night sky that will outshine it will be the Moon and the planet Jupiter.

Mars and the Moon will move closer to each other during the night, and will appear to almost touch each other at dawn. They’ll remain close tomorrow night.

Script by Damond Benningfield