Twin Comets Will Fly By Earth This Week, Astronomers Speculate The Pair Are Related

A pair of comets is set to whisk past the Earth this week and many are hoping to catch a glimpse of the rare event. The first comet, enveloped in an emerald-green cloud of gas, will shoot by early on Monday, March 21. The second is expected to fly by on Tuesday morning.

The bigger of the two comets, dubbed 252P/LINEAR, may be visible with the naked eye in the southern hemisphere as long as city lights do not interfere. As reported by the LA Times, sky-watchers in the U.S. will need a good pair of binoculars to observe the event.


However, scientists aren’t taking any chances of missing the comets during their historic journeys near the Earth. The Hubble Space Telescope, the ground-based Gemini telescopes as well as others will be focused on the space objects, offering an astonishing close-up view.

“This is one for the record books,” says Michael Kelley of the University of Maryland. “It’s a fantastic opportunity for professionals to learn more about comets, and if you have a chance to try to find them… it’s a fantastic chance to see part of history as it happens.”

Early Monday around 5:14 a.m. PDT, Comet 252P/LINEAR will come within 3.3 million miles of Earth. At that distance, it will be much farther away than the moon, but will come closer than most any other comet has ever had. According to Matthew Knight, also with the University of Maryland, the comet is about 750 feet in size and will appear bright green from the carbon gas being expelled from the celestial object.

The comet is expected to get even brighter as it races toward the sun and more gases are discharged into space.


The second comet, named P/2016 BA14, will get even closer to Earth. At 7:30 a.m. PDT March 22, the comet will be within 2.2 million miles as it zips past Earth. This will make it the second closet comet to ever fly by in recorded history.

“There are many more asteroids in near-Earth space than comets, which are significantly more rare,” said Kelley. “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.”

While it will fly by the Earth closer than the first comet, P/2016 BA14 is about half the size of P252 and will be difficult to see without a telescope. Astronomers only just discovered the tiny comet two months ago after observing it through a powerful telescope in Hawaii. They originally thought it was an asteroid as the tail was not visible.


In February, Kelley and Knight used a telescope in Arizona to take pictures of P/2015 BA14. It was then that a tail was discovered attached to the small “asteroid,” thereby making it a comet.

The bigger comet, 252P/LINEAR, was discovered 16 years ago and astronomers are unclear how the two are related. While their orbits are not exactly identical, some speculate that BA14 is a piece that broke off from 252P.

“Comets split relatively often,” Knight says. “[B]ut we rarely get a chance to study them soon after it happens, and when we do usually only the bigger fragment survives. …We have two fragments in this case.”

There are many reasons that a comet may fracture in two, according to Kelley. One possibility is the comet’s path brought it close to a planet and gravity pulled it apart. Another option is the space rock began to rotate too fast and part of it sheared off. It also might have gotten too hot when it flew by the sun and pressure built up in one particular spot which caused an explosion.

The twin comets’ unusually close Earth flyby will give researchers a rare opportunity to try and find out how the pair are related, if at all. If they end up being part of the same family, it will be an unparalleled discovery for the scientific community.

[Photo by Christopher Furlong/Getty Images]