You’ve probably already seen it this month, perhaps without realizing what it was — the bright, orange “star” in the southeast sky every evening. It’s Mars, our neighbor and fourth from the sun, in its closest approach to Earth since 2003.
It rises just after sunset in the Capricorn constellation. With clear skies, it is visible all night from its starting point in the southeast to where it sets in the southwest. This month, Mars is highest in the sky around midnight local time.
You can see it by heading outside around sunset. With the glow of dusk, it will be a beautiful time to photograph the planet. A crescent moon will be setting in the west, getting progressively larger and closer to Mars as the nights pass. On July 30, Mars and the moon will be close enough to photograph together in the southeast sky.
The exact moment of Mars’s closest approach to Earth is around 4 a.m. Eastern time July 31. It will be closer to our planet than it has been since 2003. That was Mars’s year to shine, when it was closer to Earth than it had been in 60,000 years.
A few days earlier, July 27, Mars will have reached opposition, when a planet is exactly opposite the sun in our sky. The time of opposition is the brightest that planet will be all year.
With these two events combined, Mars will be largest and brightest in the sky from July 27 to July 30.
The two events — closest approach and opposition — are not unrelated. They happen around the same time every year. Picture the Earth and Mars right next to each other on the same side of the sun. When Earth is directly between Mars and the Sun, the two planets are naturally going to be very close.
Not all close approaches are equal. If all of the planets had a perfectly circular orbit around the sun, they would be. But the orbits are elliptical, like an oval, and they are tilted. The passing of other planets can even change the shape of an orbit. Jupiter, in particular, is large enough to influence the orbit of Mars, according to NASA.
Of course, “close” is a relative term. The average distance between Earth and Mars is 140 million miles. If the orbits of the two planets came together just right, Earth and Mars could technically get 33.9 million miles apart, according to Space.com, which also reports that this has not happened in recorded history.
On July 31, Mars will be 35.8 million miles from Earth. In 2003, the planets were around 34.8 million miles apart.
The 2003 approach will remain the closest until Aug. 28, 2287, NASA says. On that day, the Red Planet will be just 34.6 million miles away.