Retrograde Motion and the Opposition of Mars

Superior planets (planets that are further from the Sun than Earth) can undergo retrograde motion when they are near opposition (the point in the sky that is opposite the Sun). Mars in particular has an opposition about every two years and so makes a retrograde loop every two years as well. Mars will next be at opposition at the end of January, 2010.

Видео Retrograde Motion and the Opposition of Mars канала astrogirlwest