Two comets in two days will be the 3rd closest comet flyby in recorded history.
Discovered by MIT’s LINEAR survey, comet 252P/LINEAR was discovered at the turn of the centruy. P/2016 BA14, the second comet was discovered just last year by the PanSTARRS telescope of the University of Hawaii. P/2016 BA14 was originally thought to be an asteroid but the Lowell Observatory team and Discovery Channel Telescope proved it to be a comet.
252P is about 750 feet long and roughly 3.3 million miles away. While BA14 is about half that size, it is much closer at 2.2 million miles. At 10:30 EST on March 22nd, it will be the closest, making it the nearest comet approach since Lexell’s comet approached at 1.4 million miles away in 1770 according to Sky & Telescope.
The orbital paths of these two currently passing comets are remarkably similar, but is this all there is to it? Not quite. “We know comets are relatively fragile things,” said Paul Chodas, manager of NASA’s Center for Near-Earth Object Studies at JPL, in a statement. “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 252P.”
Comets breaking up is nothing new. Shoemaker-Levy 9 was 21 individual pieces by the it collided with Jupiter in 1994. Astronomers think that it had passed close enough to jupiter just 30 years earlier which ripped it apart.
To observe these comets, you will probably need a pretty good telescope. Even though they are close by astronomy standards, BA14 will still be about nine times the distance of the Moon.
Your best bet will actually to see the farther 252P because it is rapidly brightening as it approaches. With some estimates predicting that it will be 100 times brighter than expected, you might be able to see it with the naked eye.
252P is, for now, only visible in the Southern Hemisphere, roughly in the direction of the constellation of Scorpius. Conversely, BA14 is passing across Ursa Major in the Northern Hemisphere. Either way, if you miss the pair this time, you’ll have to wait 150 years for their return.