In 2003 Mars was closer to Earth than any time in the past 60,000 years. Tonight Mars is slightly farther away, but won’t be this close again until 2035. Doesn’t have to be tonight, but please look up and ponder Mars.
Ours is not a symmetrical universe, celestial objects don’t march in perfect circular orbit. Mass, proximity, tilt of axis, speed of rotation and composition dictate elliptical waltzes across the night sky. Every elliptical planetary orbit has a closest point (perihelion) and farthest point (aphelion) from the Sun. On July 27, 2018 “opposition” placed Earth directly between Mars and the Sun, but thanks to elliptical orbit not closest to Earth until tonight. Time between Mars opposition and closest point to Earth varies from 8.5 days (1969) to 10 minutes (2208 and 2232).
Illustration of a telescopic view of Mars at its last opposition in 2016, in contrast to 2018. Mars appears larger through a telescope in 2018. Its larger size in our sky means it’s brighter, very bright indeed, as you’ll see if you look for Mars tonight! Illustration via nasa.tumblr.com.
Mars will still be visible after July and August, 2018, but each month it will shrink in apparent size as Earth rushes ahead of Mars in our smaller, faster orbit around the sun. As telescopes show Mars smaller in apparent sky, our unaided eyes will see Mars fade in brightness. Image via NASA Tumblr.