The “evening star” is sneaking up on a true star. Spica, the leading light of Virgo, is close to the upper right of brilliant Venus as darkness falls this evening. They’ll get even closer between now and Friday night. After that, Venus will move away from the star, adding separation each night.

Such an encounter is possible because both Venus and Spica lie near the ecliptic, which is the Sun’s path across the sky.

Spica’s position relative to the ecliptic is fixed — it never changes. Spica is moving around the center of the galaxy at hundreds of thousands of miles per hour. But it’s also 250 light-years away. That distance is so incredibly vast that it takes many human lifetimes for any change in position to become apparent.

Venus, on the other hand, is our closest planetary neighbor. As Venus and Earth orbit the Sun, our viewing angle changes quickly. So Venus changes position from night to night. That motion is quite easy to follow, especially when Venus is passing another celestial body, such as Spica.

In a few weeks, Venus will reverse course and begin to drop back toward the Sun. It’ll pass between Earth and the Sun in late October, moving from evening sky to morning sky. By the time it climbs into good view, in early November, it’ll once again be close to Spica — a frequent companion for our close planetary neighbor.

Tomorrow: discovering moons around some chunks of cosmic rubble.

Script by Damond Benningfield