Close encounters of the comet kind: Earth to see third-closest comet fly-by

Story highlights

  • At 2.2 million kilometers, this will be the third-closest a comet has approached Earth
  • It comes a day after another comet buzzed the planet
  • Astronomers think the two are related

(CNN)Earth is getting a paid a visit by a celestial traveler -- comet P/2016 BA14 -- which will buzz the planet early Tuesday morning (ET) at a distance of 2.2 million miles (3.5 million kilometers), making it the third-closest fly-by ever recorded.

The comet won't be visible to the naked eye, and will require a professional-grade telescope to witness. It will be closest to Earth around 10:30 a.m. Eastern Time.
The fly-by comes hot on the heels of another comet, 252P/LINEAR, which streaked past the planet at a distance of 3.3 million miles (5.3 million km) Monday -- the fifth-closest encounter. Given the two bodies' similar orbits, it is thought that the two may be "twins" -- with 2016 BA14 possibly a fragment that came off the larger 252P/LINEAR at some point in the past.
    Comet 252P/LINEAR flew past Earth on March 21, 2016, at a range of about 3.3 million miles (5.2 million kilometers). Comet P/2016 BA14 will safely fly by our planet at a distance of about 2.2 million miles (3.5 million kilometers) on March 22.

    Frozen balls of ice and dust

    Comets are "cosmic snowballs" of frozen gases, rock and dust, according to NASA, and can be the size of a small town. This week's visitors are much smaller: 252P/LINEAR, the larger of the two, is only 750 feet (230 meters) in size.
    As they tumble through space, their orbit can bring them near to the sun and when they heat up, form a giant glowing head and a tail that can stretch for millions of kilometers.
    The Virtual Telescope Project offers an opportunity for those of us without a pro telescope a chance to track them from here on Earth.
    "We know comets are relatively fragile things, as in 1993 when comet Shoemaker-Levy 9 was discovered and its pieces linked to a flyby of Jupiter," said Paul Chodas, manager of NASA's Center of NEO Studies (CNEOS) at the Jet Propulsion Laboratory in a statement released earlier this month.
    "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."

    Close call?

    Although Tuesday's encounter represents a remarkably close call in celestial terms, there is no danger to us here on Earth, and the two comets' visits provide a rare chance for astronomers to study them (relatively) close up, with the Hubble telescope and NASA's Infrared Telescope Facility.
    "March 22 will be the closest comet P/2016 BA14 gets to us for at least the next 150 years," said Chodas. "Comet P/2016 BA14 is not a threat. Instead, it is an excellent opportunity for scientific advancement on the study of comets."
    A comet that flew by Mars in 2014, however, was a much closer-run thing. Comet Sliding Spring came within 140,000 km (87,000 miles) of the planet then, disrupting its atmosphere and magnetic field.