People are able to see Mars by naked eyes till early February 2008, as the planet moves opposite the sun and nearest the Earth.

On average Mars moves closest to the Earth every two years and two months. These periodic encounters are due to the differences in the two planets' orbits. Earth goes around the sun twice as fast as Mars, lapping the Red Planet about every two years. Both planets have elliptical orbits, so their close encounters are not always at the same distance.

This year, Mars comes as close as 54.8 million miles (some 87 million km) -- not as close as the historic pass-by of 2003 (55.36 km), but still a night-brightener.

Although 2003 offered astronomers a view of Mars closer than this year's approach, Hubble's most recent detailed look at the red planet shows it's free of dust storms. However, ice crystal clouds in the northern and southern polar caps can be seen. 

 Source : Xinhua English