By Dave Grosvold
|
| Looking east at 9:00 PM CST Jan 14, 2010 |
January 2010 is a great time to observe Mars. This is the time just before the Red Planet passes closest to earth in its 687-day journey around the Sun. When Mars appears bright in the night sky, it is in
opposition to the Sun, meaning that it is opposite the Sun in the sky as seen from Earth. It is also closer to Earth at this time than at any other time in its orbit. As such, this is when it is brightest and best positioned for observational study. Whenever Mars or any other planet is visible in the night sky for a period of weeks, this entire period is said to be a single
apparition. Mars’ latest apparition began several weeks ago. This week, you will see it above the eastern horizon early on clear cold evenings as a bright ruddy “star”. By 9:00 PM, it will be high enough above the horizon that you can view Mars without the usual distortion caused by the thicker atmosphere lower on the horizon.
|
| Looking west-southwest at 6:00 PM CST Jan 17, 2010 |
Mars will actually make its closest approach to us in its orbital cycle on January 29, 2010. As Mars approaches opposition it begins a period of
retrograde motion, which means it will
appear to move backwards in a looping motion with respect to the background stars. This is due to the fact that Earth passes Mars in its orbit. So initially, we see it in front of us, and then as we pass, it falls behind. The duration of this retrograde motion lasts for about 72 days, and Mars reaches its peak luminosity in the middle of this motion this coming March.
Careful observers should be able to identify the larger features on Mars’ surface using a small telescope. These include the polar ice caps and Syrtis Major, which appears as the largest dark splotch on Mars. These darker areas were once thought to be seas or canals, but have been revealed as areas of darker rock with less dust than the brighter surroundings.
Also this week,
Jupiter is low in the southwest just after sunset. Jupiter will continue to get lower in the western sky every evening until it sinks below the horizon. On Jan 16, if the sky is clear, look for the waxing crescent Moon very low on the western horizon. By the evening of Jan 17, the Moon will be very close in conjunction below Jupiter in the western sky. A conjunction occurs when two or more celestial objects appear very close together in the night sky.
