First, the important stuff: No one is getting hit with a comet today. Or tomorrow.
Now, the fun stuff: A pair of twin comets is in the process of zipping past Earth. On Tuesday morning, one will pass closer to our planet than any comet since 1770. It's the third-closest flyby in recorded history.
Now, the surprising stuff: It doesn't take much to break the record for cometary Earth proximity. Monday's comet, the fifth-closest ever reported, was 3.3 million miles away from Earth at its closest point. The comet shooting by us on Tuesday, dubbed P/2016 BA14, will still be 2.2 million miles away — more than nine times farther away from us than the moon — when it makes its "close" encounter.
"There are many more asteroids in near-Earth space than comets, which are significantly more rare," Michael Kelley, an astronomer at the University of Maryland, told the Los Angeles. "When a comet does come this close to Earth it is something to get excited about, and take advantage of to learn whatever we can."
Scientists initially thought that P/2016 BA14 was an asteroid — a space body made up of metals and rocky material. But then they spotted its tail: Because comets are mostly made up of ice with a little dust and rock mixed in, they spew gas into space as the sun warms their frozen surface.
They soon realized that the comet shared an unusually similar orbit with 252P/LINEAR, which is about 750 feet across and made its closest pass of the Earth early on Monday. The researchers believe that Tuesday's comet, which is about half the size of its twin, may have broken off of it at some point.
"We know comets are relatively fragile things. . . Perhaps during a previous pass through the inner-solar system, or during a distant flyby of Jupiter, a chunk that we now know of as BA14 might have broken off of 252P," Paul Chodas, manager of NASA's Center of NEO Studies (CNEOS) at the Jet Propulsion Laboratory said in a statement.
252P/LINEAR has been unexpectedly bright, and may even wind up being visible with the naked eye at some point during the week — so keep your eyes peeled. Even though the smaller twin is much closer, it probably won't be quite as visible — though backyard telescopes should still be able to catch a glimpse.
The Virtual Telescope Project will host a live broadcast of the comet's transit starting at 5 p.m. Eastern on Monday. Meanwhile, scientists will be using its scopes to study the unusually friendly comet.
"Comet P/2016 BA14 is not a threat," Chodas said. "Instead, it is an excellent opportunity for scientific advancement on the study of comets."
Correction: A previous version of this post stated that the larger comet was 750 miles across, instead of 750 feet. That would be one big comet! The text has been corrected.