If you see a blazing red light in the sky tonight (July 31) don’t panic.
It’s just Mars, rushing toward Earth.
Not that there is any danger of collision—the two planets will be 35.8 million miles apart, give or take a few miles. But Mars will be closer to the Earth than it has been since 2003—its second-closest approach in the past 60,000 years.
Tonight the red planet will be at its brightest.
Every 15 to 17 years, Mars and Earth pass each other in opposition while Mars is at perihelion—the point in its orbit where the planet is closest to the sun. When these two conditions coincide, the two planets are as close together as they can get.
The distance between the two is not constant. Planets’ orbits are constantly, minutely changing, as they tug on each other with gravitational force. If one of the gas giants like Jupiter or Saturn is in the neighborhood, it will pull all the inner planets toward it a little.
“Right now, we’re approaching Mars when Mars is near the closest point to the sun on its orbit,” Betts said. “But next time we come close to Mars, it will be further from the sun, and further from us.”
If you don’t want to wait that long, take a few minutes this evening to step outside and glance skyward. If you have binoculars, or better still, know someone with a telescope, take advantage of the opportunity.
Unfortunately, weather conditions might make it hard to see Mars clearly.
Not weather on Earth—weather on Mars. Planetwide dust storms might obscure features, which even a small telescope would usually be able to pick out, with Mars being so close.
“It happens every couple of years, but this is the worst we’ve seen in a long time,” Betts said.
The weather on Earth might not be suitable for stargazing tonight, either—but Mars will be exceptionally bright through the first week of September.
