Jupiter is backing up. The planet is in the “retrograde” portion of its trip across the sky. Instead of its usual eastward motion against the background of stars, it’s moving to the west. And right now, it’s about half way through that “reverse” period. That’s because Jupiter is at opposition – it lines up opposite the Sun in our sky.

Some people see a planet’s retrograde period as an omen. What kind of omen depends on the planet and the person making the prognostication.

In reality, retrograde is just an optical illusion. The planet doesn’t move backward at all. It only appears to do so because of the relative motions of Earth and the other planet. Now, for example, Earth is moving past Jupiter in our smaller, faster orbit around the Sun. As we do so, Jupiter appears to stop and back up for a while.

The effect is like passing a slower car on the highway. For a while, the other car appears to move backward against the background of buildings and trees. But when you get far enough away it appears to resume its forward motion. The car itself hasn’t actually changed direction – it only looks that way.

Jupiter entered retrograde in early October. It’ll resume its normal course in early February.

Jupiter is low in the east-northeast as darkness falls, and climbs high across the sky during the night. It looks like a brilliant star, with Aldebaran, the brightest star of Taurus, close by.

More about Jupiter tomorrow.

Script by Damond Benningfield