You are here

Moon and Planets

November 30, 2013

The crescent Moon finds itself flanked by a pair of planets as day breaks tomorrow. Saturn stands above the Moon, with brighter Mercury about the same distance to the lower left of the Moon. They’re quite low in the sky, but binoculars will help you separate them from the glow of early twilight.

Saturn is a “superior” planet, which means it orbits outside Earth’s own orbit around the Sun. So over time, Saturn crosses the entire night sky.

Right now, the planet is just emerging into the dawn sky after recently passing behind the Sun. But as the days and weeks roll by, Saturn will rise a little earlier and stand a little farther from the Sun each day. By the middle of next spring it’ll rise at midnight, then move into the evening sky. Finally, late in the year, it’ll disappear in the evening twilight as it prepares to pass behind the Sun — starting the cycle all over again.

Mercury, on the other hand, is an inferior planet, because its orbit is inside Earth’s. In fact, Mercury is closer to the Sun than any other planet. As a result, Mercury never wanders far from the Sun in our sky. At best, it’s visible for a little while before sunrise or after sunset.

This is actually a fairly good morning appearance for Mercury. But the planet is beginning to drop back toward the Sun, so it’ll soon disappear from view. It’ll make a brief appearance in the evening sky in January, then move back to the morning sky in March.


Script by Damond Benningfield, Copyright 2013

Get Premium Audio

Listen to today's episode of StarDate on the web the same day it airs in high-quality streaming audio without any extra ads or announcements. Choose a $8 one-month pass, or listen every day for a year for just $30.