M ars is at opposition tonight. That means it is "opposite" the sun from Earth's perspective, rising in the east as the sun sets in the west. It is Mars' closest approach to Earth this year, about 62 million miles. It's the best time to see Mars through a telescope. Or just step outside after 8 p.m. on the next clear night. Look east for a moderately bright, reddish "star" just below the twin stars of Gemini. We have three working satellites orbiting Mars, and two surface rovers, one stuck in sand.