Mars will be at opposition in the small hours of March 4, 2012. At opposition, Earth will overtake Mars during its revolution around the Sun and will pass between Mars and Sun. Consequently, the distance between Earth and Mars will be minimal. This has rendered Mars as one of the brightest objects in the night sky for last few weeks. Moreover, being close to Earth, Mars exhibits relatively larger angular diameter. Mars will be closest to the Earth on the next day i.e. March 5, 2012. As Mars and Sun are on opposite sides of Earth, Mars now-a-days rises when sun sets and vice versa. Due to this, Mars can be spotted in the sky throughout the night.
The present closest approach is however not really 'the closest approach', as Mars can come within about 55 million kilometers of Earth under favourable oppositions. This happens when the opposition takes place when Mars is near perihelion. At the present apparition, Mars is close to its aphelion position.
Details about Mars on the day of closest approach:
Constellation: Leo
Closest Approach: 05/03/2012 (21.30 hours IST)
Earth-Mars distance: 0.6737 A.U. (100.8 million km)
Sun-Mars Distance: 1.6643 A.U. (249.6 million km)
Angular diameter of Mars: 13.9”
Apparent Magnitude: -1.2
Illumination 99.9%