Mars Opposition 2012

About a month from today, on March 3rd, the planet Mars will pass through opposition.

Mars orbits the Sun every 1.88 years, with Earth only taking one year for each orbit. Like two runners on a track the two planets race each other around the Sun. But we have the inside lane, lapping the red planet every two years. These events are called opposition, when Mars is closest to us and best positioned for viewing by earthbound telescopes.

Closest approach of the two planets is not necessarily on the same day as opposition, but can vary up to two weeks. This year closest approach will occur March 5th with the two planets approaching to 99,331,411 km (61,721,554 miles) at 07:01HST.1 At this distance the red planet will show a disk 13.89″ arc-seconds across in the eyepiece.2

Mars during the 2005 oppositionMars during the 2005 opposition

Do not worry about viewing on the 3rd or 5th, any time in the month leading up to and after opposition the viewing will be very good. With even a modest telescope it should be possible to see the bright polar caps and light and dark markings on the planet.

All month Mars will be visible throughout the night, high in the sky at midnight. This is the time to enjoy observing our closest neighboring planet while it is nearby and high in the night sky.

1) 2012 Mars Opposition at SEDS
2) The 2012 Aphelic Apparition of Mars

The Moon and Venus

This evening a nice crescent Moon will join Venus in the dusky sky. The pair will be reasonably close, about 8° apart. Venus is currently shining very brightly at about -4.1 magnitude, contrasting nicely with a 9% illuminated Moon. The two will still be close tomorrow, about 9° apart with the Moon 15% illuminated.

Venus and Neptune

Venus will pass about one degree from Neptune on January 12th. The two will be quite close for several days, under 3°, from the 10th to the 15th, with close approach on the 12th. As the two are located high in the evening sky they are well placed for observation. This is an opportunity to find the distant ice giant with no difficulty at all. A telescope is required to see Neptune, at about 8th magnitude Neptune is about 60,000x dimmer than Venus shining at -4 magnitude. Check a chart for proper identification, there are several moderately bright stars in the region to confuse with the dim planet. On the 12th, a 6.9 mag star will directly between the two. The odd green-blue color of Neptune should help distinguish the planet.

Mercury Transit

About a dozen times a century Mercury passes in front of the Sun as seen from Earth. The event is observable with a modest telescope and a solar filter, Mercury can be seen as a small black dot crossing the surface of the Sun. If half of those happen when the sun is below your horizon the average person will have the chance to observe five or six in a lifetime. Since the next opportunity will not occur until May 9th, 2016 I didn’t want to miss this one!

Photographing a Mercury Transit
90mm refractor Violet Haze photographing the transit
I took the day off.

Considering that Mercury never gets very far from the Sun means that most of the time you can observe Mercury it is low on the horizon and is typically seen through a great deal of atmospheric distortion. A transit is one exception to this, during a transit mercury is a sharp disk, very different from the multicolor jello ball that is usually seen.

The 2006 Transit was well timed for observation across western North America, starting just after noontime and ending at 5:09pm MST. This put the Sun high in the sky for all but the last part of the event. Our weather cooperated as well, delivering a cloudless blue sky the entire day in place of the clouds that had been forecast. The air was reasonably steady as well allowing good photographic and observing conditions.

I took advantage of the weather and photographed almost the entire transit, all but the very end when the sun sank below the trees in my neighborhood. I used the Canon 20Da and setup a timer to shoot every 5min. The only issue was the inability to do a polar alignment on the mount when setting up in the middle of the day. The result was I had to manually guide the scope every 10-15 min to keep the sun centered.

I got plenty of good photographic material, enough for a few single photos as well as an animation of the transit. A transit is an impressive demonstration of the scale and arrangement of our solar system. Not hard to visualize the reality of those textbook drawings of planetary orbits after you have had such an opportunity to see the real thing.

No complaints on my second Mercury transit.

Mercury Transit 8Nov2006
The Mercury transit of 8 Nov 2006 in progress. Mercury is about halfway between the center to the bottom, a large sunspot complex is visible on the left edge. Photo with a 90mm APO refractor, a Thousand Oaks full aperture filter and a Canon 20Da camera.