Hold on to your hats and keep a pair of binoculars handy: After a 26-month sprint around the track of the solar system, we are about to lap Mars again. Today, the red planet is in “opposition,” an event that puts Earth between Mars and the Sun. On June 21, Mars will be at its closest distance from Earth since 1988, a mere 67.3 million kilometers (approximately 42 million miles). All summer long, Mars will be brighter than usual, particularly for sky-watchers in the southern United States and those in the Southern Hemisphere.