Mars - up close and personal
If you've been outside after it gets dark lately, you may have noticed the brilliant reddish star in the nth east. But that's no star; it's Mars! About every year and a half, the Earth passes Mars as they both orbit the Sun, very much like how a faster racing car on the inside track laps a slower-moving car on the outside track.
Mars was at opposition this week ,on January 30, and now is a good time to look at our sister world in a telescope. Last week the Red Planet was only 99 million kilometers away and looked bigger through a telescope than at any time between 2008 and 2014.
In the evening Mars can be seen from around 10pm AEDT low in the northeastern sky as the brightest (and clearly red) object in the sky. . Mars is a distinct nearly full disc in a small telescope, although somewhat small. Larger telescopes will be needed to distinguish surface features. Red Mars is in the constellation of Cancer and from January 31 is within a binocular field of the Beehive cluster.
When Earth does lap Mars, the Red Planet's on the opposite side of the sky from the Sun, rising at sunset and setting at sunrise – we say that Mars is at opposition when that happens. When it does, we get two advantages in one: it's at its closest point, so it's bigger in telescopes, and it's up all night so you can observe it at your convenience. This will be a good week to look at Mars. Mars is looking more impressive than usual. All week it will very nearly match the brightest star in the night sky, Sirius, which is off some distance to the right of the planet.
Roughly every two years the Earth laps its fellow planet, passing it up on the inside track of our smaller orbit. When this happens, Mars appears quite a bit brighter than usual, and also larger in a telescope. The orbit of Mars is noticeably oval rather than circular. Moreover, the Sun is not at the center of the orbit. Johannes Kepler taught us back in the 17th century that planets travel in orbits shaped like ellipses, not circles, and the Sun was at one focus of the ellipse, not at the centre.
As a result, how close we come to Mars depends on where the Red Planet is in its orbit. Back in 2003, it was very close to its perihelion, its closest approach to the Sun. We came within about 35 million miles that year, closer than we've been in more than 50,000 years. This time, however, we're nearly on the other side of the solar system. The space between our respective orbits is much greater. We won't get any closer than 61 million miles this time.
Republished from: http://www.davidreneke.com/astro-space-news
