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car appear to slow down even more as you watch it against the more distant landscape (perhaps a grandstand filled with onlookers). Just as you are passing the slower car, you see it appear to reverse its motion and move backward against the grandstand. The slowing - and reversed motion - of the slower car is purely geometric illusion. The car doesn't really slow down to let you pass; its driver still wants to win the race and is pushing forward as fast as it can. But you are moving faster still, and your faster motion as you pass the other car creates the illusion that it slows and even moves backward for a time. You've probably seen this happen on a highway many times, as you pass a slower car.
• So Earth and Jupiter are planets on the great racetrack of the solar system. For the next several months Jupiter will appear to drift slowly westward among the stars of the constellation Taurus the Bull. You guessed it … we'll soon pass between Jupiter and the sun.
• On December 3, 2012, Jupiter will be at opposition. At opposition, the Earth passes in between the sun and Jupiter, at which time Jupiter lies opposite the sun in Earth's sky. If you could look down upon the solar system plane on that day, you'd see the sun, Earth and Jupiter making a straight line in space, with Earth sitting in between the sun and Jupiter. Because Jupiter is opposite the sun at opposition, Jupiter will be in the east at sunset in early December, soaring to its highest point in the sky at midnight and setting in the west at sunrise.
• What's more, the 2012 opposition of Jupiter will present Jupiter nearest to Earth until the opposition on August 20, 2021.
• In the months around opposition, Jupiter will be moving westward - in contrast to its nor

mal eastward motion - in front of the stars. It ends its westward or retrograde motion on January 30, 2013. How can you notice its westward motion? You can notice it - over a period of several weeks - if you note Jupiter's position relative to some nearby stars. Then after January 30, 2013, you can watch it shift eastward again
• Right now Jupiter is in the eastern sky at middle to late evening. It's rather high in your southern sky by daybreak. On the up side, Jupiter is very easy to identify - just face east at late evening tonight and look for the brightest object in the sky. Also, on the plus side, the King of the Planets is now passing through Taurus, which is a particularly prominent constellation. Watch how Jupiter moves relative the bright star Aldebaran and the Pleiades star cluster. At the end of Jupiter's retrograde in late January 2013, you'll see Jupiter in between Aldebaran and the Pleiades.
• If you start tonight (or sometime soon), and plot Jupiter's apparent position every week or so through the end of January, you should notice Jupiter's retrograde or westward motion in front of the backdrop stars.
• Bottom line: The giant planet Jupiter begins retrograde, or westward, motion in front of the stars now. Its stationary point, where it is poised motionless in front of the stars, is today. Jupiter will move westward until January 30, 2013. Its apparent westward motion is caused by the fact that we will pass between Jupiter and the sun on December 3, 2012. At that time, Jupiter will be said to be at opposition to the sun. This will be Jupiter's closest opposition until 2021.