Moon and the Twins

The twins of Gemini are pretty popular among the worlds of the solar system right now. Mars lined up side by side with them last week, and Venus will join them next week. But tonight, it’s the Moon’s turn. Pollux and Castor stand to the Moon’s right and upper right this evening, with Pollux closer to the Moon. And to spice things up a bit, Venus is close below them — the brilliant “evening star.”

All of the close encounters are made possible by the location of the twins. They’re not far from the ecliptic — the Sun’s path across the sky. The Moon and planets travel close to the ecliptic as well. So when they slide through Gemini, they’re naturally going to pass near the twins — with Pollux always the closer one.

As the seasons change, though, so do the timing of those encounters. That’s because Earth basically has two “days” — one related to the Sun, and the other related to the rest of the stars.

It takes our planet 23 hours and 56 minutes to make one full turn relative to the panoply of stars. But during that time, Earth moves about one degree in its orbit around the Sun. So our planet has to rotate an extra four minutes to bring the Sun back to the same position in the sky — giving us a 24-hour day. On that clock, all the other stars rise and set four minutes earlier each day. So as the seasons change, the stars move across the sky — changing the timing of their encounters with the Moon and planets.
 

Script by Damond Benningfield