Saturn and Venus bracket the pre-dawn sky now. As Saturn drops from view in the west, Venus nudges into view in the east. Saturn looks like a bright star, while Venus is the brilliant morning star.

The planets are both sliding eastward against the background of distant stars.

Saturn lined up opposite the Sun a couple of weeks ago. For a few months around that point, the planet looks like it’s “backing up” against the background of stars – a result of the relative motions of Saturn and Earth.

Earth is closer to the Sun than Saturn is, so our planet moves faster. It overtakes Saturn every 13 months, making Saturn appear to shift into reverse. It’s actually still moving in its usual direction – only our viewing angle is changing. It’s like passing another car on the highway. For a while, the other vehicle looks like it’s moving backward against the background of buildings and trees. When you move far enough past it, though, it appears to resume its normal forward motion.

Saturn will end its backward motion and shift back into forward at the end of November.

Venus, on the other hand, is about to pass behind the Sun as seen from Earth, so it’s dropping closer to the Sun every day. That’s also a result of the orbital motions of the two planets. Venus will disappear in the twilight in December, and cross behind the Sun in January – depriving us of the “morning star.”

More about Saturn tomorrow.

Script by Damond Benningfield