Astronomers are so excited about a cosmic event happening this Sunday that some of them would probably jump at the chance of getting a one-way ticket to Mars. A comet knocked out of the Oort cloud at the edge of the solar system millions of years ago is set to buzz by Mars at a "mind-bogglingly" close distance of 87,000 miles—only a third of the distance from Earth to the moon, and far closer than any comet has come to our planet in recorded history, USA Today reports. The comet, the size of a small mountain and named Siding Spring after the observatory that first spotted it, was formed at the dawn of the solar system, and scientists have never been able to get a good look at anything like it before.
"Think about a comet that started its travel probably at the dawn of man and it's just coming in close now," a John Hopkins University astrophysicist tells the AP. "And the reason we can actually observe it is because we have built satellites and rovers. We've now got outposts around Mars." The NASA rovers on the surface of Mars will be in position for what's expected to be a spectacular view, and spacecraft in orbit around the planet—including NASA's newly arrived Maven—will observe the 5-mile-wide comet before ducking behind the planet to avoid debris from its tail. Space.com has some viewing tips for the flyby that scientists believe happens only once in a million years, though the best views for non-Martians will be from our planet's Southern Hemisphere. (Read more comet stories.)