The God of War is on the Horizon

The old Roman god of war will be "marching" its way into our evening sky this month. (Yes, we do indeed call this month "March" because it was when the Roman Army could once again get on the move.) The planet Mars has been keeping a discreet distance from us for quite some time. It will finally start becoming prominent again in our evening sky this month. As March progresses, Mars will become an eye catcher, a dazzler in binoculars, a treat in a small telescope, and a rewarding experience in a larger one.

The earth is catching up to Mars as it does every two years and two months. Mars will reach opposition on April 8. Since the orbits of our two planets aren't exactly circular (and because the planes of our orbits aren't quite the same), we pass at different distances at each opposition. The distance varies from about 56 to 100 million km, about a factor of two. That means the apparent size of its disc can vary from about 13.9 to 25.1 arcseconds at opposition. Its maximum brightness also varies accordingly.

In 2003, Mars made its closest pass in 50,000 years! However, it is now nine years into a fifteen year cycle of far and close approaches. This spring Mars will pass a healthy 92 million km away and present us with a disc only 15.1" wide, but this will still be its best pass in seven years. It will become brighter than any star in the sky at magnitude -1.5 and compare most favorably to nearby Spica, a star famous for being almost exactly magnitude +1.0. It will also be quite noticeably red.

Mars begins the month of March below the evening horizon, rising in the east around 10 p.m. But it will rapidly rise earlier and grow brighter each night as the earth overtakes Mars on the inside of the track, as it were. By the end of March, it will almost become the brightest object in the sky at times. (In early April, it will be.)

Mars will certainly become the reddest object to the naked eye. Binoculars help bring out its color, but it takes a telescope to show Mars as a disc. On this pass, it will take a 150-mm/6-inch scope to see details such as the North Polar Ice Cap.

The best time for viewing will be toward the end of March and into early April near midnight. Our weather and seeing should be improving by then also.

While you're gazing at the Red Planet, keep in mind all of the robotic activity going on up there. NASA/JPL currently has two orbiters and two rovers examining Mars, and the European Space Agency has an orbiter working with us. The Curiosity rover continues to detect simple organic compounds in the dry lakebed of Gale Crater. While not all organics are biogenic, they are difficult to explain in the absence of life. Stay tuned! Maybe it's time to get more excited about sending a team of humans to Mars.

Two more space probes are on the way. NASA/JPL's MAVEN orbiter will study the Martian atmosphere to determine how Mars lost its water and atmosphere over time. MAVEN is flying in loose formation with India's Mars Orbiter Mission. It is a very ambitious "technology demonstrator" mission designed to show (especially to their regional space revival China) that they have the technology to conduct an interplanetary mission. While scientific objectives are secondary, the probe is designed to add to humanities pool of data on the Martian surface and atmosphere. Both probes are due to arrive in September. So far, so good. Let us look forward to welcoming India to a very exclusive club!

Dark Sky Watch

With such a mild winter, it's hard to think in terms of spring coming so soon.

Yet, it officially arrives on Mar. 20 at 8:30 p.m.

Jupiter is still high at sundown, but Saturn is best seen in the early morning. Venus will be bright, but low in the east late in the month.

Sunrise/Sunset (Mar. 1) 6:23 a.m./5:50 p.m. PST (Spring forward Mar. 9)