After a slow crawl across the predawn darkness earlier this year, Mars is finally moving into the evening sky - just as it comes its closest to Earth in 15 years. According to Sky and Telescope magazine, the two planets' centers will be separated by just 35,784,871 miles or 57,590,017 km on July 31st at 3:50 a.m. EDT (7:50 Universal Time).
This is the closest Mars has come to us since August 27, 2003, when the separation was 34,646,418 miles. On that date, the Red Planet was closer to Earth than it had been since 57,617 BC.
Right now Mars appears especially big and bold in the night sky. Its peak brightness, as measured with the magnitude scale used by astronomers, will be -2.8. This means Mars now appears twice as bright as Jupiter, which is also prominent now in the southwestern evening sky, and it will continue to outshine Jupiter until the first week of September.
"When you first spot Mars rising in the east after sunset, you'll be startled by how bright it looks," notes Diana Hannikainen (pronounced "huhn-ih-KY-nen"), Sky and Telescope's Observing Editor. "Its pale orange color is unmistakable." In fact, it's called the "Red Planet" for a reason: Mars really has a reddish-orange hue, caused by rust-colored iron oxides on its surface.
There are actually two related events involving the Red Planet this week:
JULY 27: At 1:07 a.m. EDT (5:07 UT), Mars reaches "opposition." This means that the planet appears directly opposite the Sun as seen from Earth. Mars rises at sunset, remains in the sky all night, and sets as the Sun rises. Mars takes 1.88 years (687 days) to circle the Sun, and faster-moving Earth essentially "laps" its neighbor about every 26 months. The previous opposition of Mars was May 30, 2016, and the next one will be October 6, 2020 - but on those dates the Red Planet will be considerably farther away than it is now.