Mars will be at its biggest and brightest in two years when it arrives at opposition to the sun Saturday. The Red Planet comes to about 63 million miles from Earth during opposition and will shine at a brilliant --1.2 magnitude, just slightly dimmer than Sirius, the brightest star in the night sky.

Mars will continue its backward or westward motion toward Leo's brightest star Regulus until April 16, after which it resumes direct motion (west to east) against the background stars. Mars will remain an "evening star" throughout the spring and summer, but it will grow dimmer as Earth travels away from Mars. By the end of March, the Red Planet will have faded to --0.8 magnitude.

This week, look for Mars to the right of the triangle of stars that form the hindquarters of Leo, 30 degrees above the eastern horizon at 9 p.m.

Weather permitting, the Buhl Observatory at Carnegie Science Center will have an extended Skywatch session for observing Mars this weekend. Call 412-237-3327 for information.

First Published: February 27, 2012, 5:00 a.m.