The red planet is unusually bright as it moves into position where it can be seen from Earth.

Mars only spends the better part of two years as an undistinguished ”star” shining with a diminished light. It hardly catches our eye.

But when the Earth – with its ”inside” orbit – finally catches up with Mars about every 26 months, something wonderful happens: it appears to come alive.

At such an event, Mars is said to be in ”opposition”. It’s nothing to do with politics but, rather, it is in the opposite part of the sky to the sun, at sunset. The geometry of Earth’s orbit and that of Mars line up so they are both on the same side of the sun and at their closest. We’re about to reach such a stage this weekend, when Earth draws level with the red planet and then, like an 800-metre runner on an inside lane, overtakes it.

While this happens, a strange phenomenon may be observed – it used to drive astronomers batty as they had no explanation. We now know it’s just our perspective from an inner orbit.

Until late January, Mars was moving slowly eastward night by night, then it stopped dead still for a couple of days and began moving back towards the west – we call this retrograde motion.

It will continue in this direction, getting closer to Regulus, the brightest star in Leo, until Easter, when it will stop once more for a few days.

Mars will then continue in an easterly direction until the next opposition in 2014.

In the two months leading up to an opposition, there is a gradual but dramatic rise in brightness. I’ve even had stargazers ask if there’s a new supernova in the sky.

By now there’s no mistaking Mars for anything else; it ranks as fourth brightest in the sky after Venus, Jupiter and Sirius.

Furthermore, it has a distinct orange hue and is found low in the east half-an-hour after sunset. There is no other comparable object in that part of the sky. If it helps, it’s in the hindquarters of Leo the lion but the truth is you will spot Mars way before you see any of Leo’s other stars.

Related articles

• NASA budget cuts threaten Canadian contribution to Mars missions (vancouversun.com)
• Mars rocks indicate relatively recent quakes, volcanism, on Red Planet (physorg.com)