Big Planets and Bright Planets
By Calvin L. Chrisman
There are many planets to see in November as the winter constellations begin to come into view. The two biggest, Jupiter and Saturn are visible in opposite directions as the Sun rises; while the two brightest, Jupiter and Venus are visible in opposite directions as the Sun sets. OK we’re talking about three planets and it sounds a little confusing. Try it this way.
For the biggest planets, go out on a clear night just before sunrise. First, look toward the southeast where Saturn will be rising before the Sun comes up. It will be higher and higher in the sky as the month progresses. It will be slightly brighter than first magnitude and will slightly out-shine Spica, the blue-white star a short distance to its right. If you do this on the morning of November 22nd these two will be joined by the crescent new Moon. After you have enjoyed this sight, turn around and look west. You will see bright Jupiter, shining at magnitude -2.9 (remember that minus magnitudes are brighter) setting in the West. Jupiter is just past being directly opposite the Sun; it is relatively close to us in its orbit and so is putting on a good show.
For the brightest planets, go out on a clear night just after sunset. Again, look toward the east, now you will again see Jupiter, but this time it will be just beginning its transit of the night sky. If you have a telescope, later in the evening, see if you can spot the four moons that are visible in small scopes and perhaps the great red spot on its surface. After observing Jupiter, turn to the west and you will see Venus shining at magnitude -3.9. It will be brilliant and will be easy to spot within fifteen minutes or so after sundown. As a bonus, take along some binoculars; wait another fifteen or twenty minutes after sundown, and scan the sky just below Venus. You should be able to see the planet Mercury sitting about two degrees lower in the sky.
We are beginning to learn new things about Mercury as NASA’s Messenger spacecraft settles into orbit around the planet. It has long been thought that Mercury was geologically inert; just a ball of rock being hit by the occasional meteor or asteroid and being fried on one side by the Sun and in deep freeze on the opposite side. Messenger has recently sent back images that may indicate some type of volcanic activity indicating a magma core to the planet. We won’t know for a while, but we can enjoy seeing Mercury in the evening sky.