The universe smiles down on us Monday

If you haven't been watching Venus grow closer to Jupiter every night, I suggest that tonight would be a good time to start. Venus and Jupiter are very easy to find.

Just face west where the Sun disappeared and as it grows dark, you'll see two very bright stars. The upper one is Jupiter and the lower one is Venus.

Keep watching every night this weekend, because on Monday, Dec. 1, there will be an astounding conjunction of these two planets and the crescent moon. It'll be easy to find if the clouds let you see it at all.

Just watch the sunset on Monday night and look for the smiley face in the western sky. Venus will be the left "eye", Jupiter will be the right "eye" and the moon will form the smile.

Venus and Jupiter will be making their closest point of approach for this pass on Monday night. Start looking for the smiley face at sunset, but it won't set until 8:30 p.m., so there'll plenty of time for the clouds to move out of the way. Mark your calendars now for Monday to see the smiley face in the sky!

After you find Jupiter and Venus this week, turn completely around at 7 p.m., or so, and look about a fist-width above the horizon. You'll see a bright red star. That's Aldebaran.

There's an interesting story about the moon and Aldebaran that involves a famous astronomer. Edmund Halley is best known for predicting the return of the comet that's now named for him, but Halley made other contributions to science that may have been more important.

For one thing, Edmund Halley was a very good friend of Isaac Newton and it was Halley who persuaded Newton to publish the Principia, arguably the most important scientific document in history. Halley used Newton's laws of gravity to predict the time of Comet Halley's return.

Halley's great interest was in orbital mechanics and he plotted the courses of the planets and of the moon far into the past. In 1735, Halley plotted the path of the moon and discovered something strange. An occultation occurs when the moon passes directly between the Earth and a distant star and there was a very famous occultation of the star Aldebaran by the moon in 509 A.D.

Aldebaran is close to the ecliptic plane, the path that the moon and planets all follow in the night sky and Aldebaran is periodically covered by the moon. But Halley's calculations showed that the moon could not have covered Aldebaran in 509 AD. Obviously, something was wrong but Halley did his calculations over and over and always got the same result.

He proposed something revolutionary. He said that in the 1,200 years since the 509 AD occultation, Aldebaran had moved. Although that theory wasn't widely accepted at the time, today we know it's true.

Although the stars are so far away their motion appears glacially slow, Aldebaran, at 68 light years, is fairly close -- so its motion is apparent if 1,200 years have passed. But don't expect the star patterns to change in your lifetime. They'll look the same in 2050 as they do tonight.

Go outside tonight and gaze at the star patterns of your ancestors. Find some planets and watch their positions change from night to night. Have a look at the smiley face in the western sky on Monday night. Spend some quiet, quality time with your kids. It's the best present you can give them. Look up tonight, the universe awaits you!