Thursday, November 29, 2007

Three days ago on the evening of the 26th Molly was struck by an intriguing sight that she had forgotten was coming. I'm speaking of the conjunction of Mars with the waning gibbous Moon in the constellation Gemini. Molly tends to shut down her stargazing in the winter months, even though these are perhaps the best of times because Molly hates cold beyond all other things. Thus it was that I was surprised by the sight that I saw. On that evening mars came within 1.5 degree of the Moon, just to the southeast (yes, the photo presented above is from the last conjunction in the spring of this year, so don't berate me too much).
Last Monday's view of Mars was perhaps one of the most striking, but for those with a specific interest in the planet itself it is hardly the best that will occur this year. About every 26 months Mars makes its closest approach to Earth, and this is the time when amateur astronomers have the best view of the red planet. Mars is actually the only planet on which one can see surface detail in the usual backyard scope, though this detail may be obscured this year due to recent dust storms on the planet. This year Mars will rise higher in the sky than it will for any time until 2022. The point of closest approach will be on December 19th. The apparent size of Mars on that date will be about 15.9 arc seconds, far lower than the close approach of 2003 when it had an apparent diameter of 25.1 arc seconds. The best times of viewing will be in the middle of the night. If the dust in the atmosphere has cleared you may be able to see the gradual turning of Mars from night to night because Mars' rotation period is 24 hours and 37 minutes. Thus each night you will see about 1/40th more of the Martian surface towards the East side. As Mars reaches its maximum size in December the northern hemisphere spring will have begun (Martian Equinox is on December 9th). The northern polar icecap will be prominently visible.
The closest approach of Mars to the Earth(88 million kms) will not be exceeded until 2016, and thus this is the best time to observe the surface for another 7 years. On the evening of December 23rd there will be an occultation of Mars by the Moon visible on the west coast and points west of Lloydminster on the Alberta/Saskatchewan border. Further east, such as here in Winnipeg, there will be merely another close approach such as what Molly saw three nights ago.

No comments: