|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
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
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
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!