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Hubble Captures Earth’s Closest Encounter With A Comet In Recorded History

By Shelley Hazen
Published on: 02:06 PST, May 16, 2016

Hubble recently captured the closest encounter between Earth and a comet in recorded history, and it will never get that close again.

The comet, 252P/LINEAR, whizzed past Earth on March 21, when it was only 3.3 million miles from the blue planet, or 14 times our distance to the moon, CNN reported.

Three million miles may not sound very close, but that distance makes the comet’s visit the planet’s fifth-closest encounter of any kind, ever.

The comet was already notable because it was one of two to zip past Earth around the same time, as the Inquisitr previously reported. The double fly-by featured the larger 252P and its little sister P/2016 BA14; the former was 750 feet across and the latter about half that size.

The smaller of the two actually flew closer to Earth, but it was far too small and dim for Hubble to capture it in a picture.

Last week, NASA released images taken by Hubble of the comet flying past Earth. The pictures were taken on April 4, when the comet was about 8.7 million miles away and two weeks after its closest encounter with Earth, The Washington Post reported.

Hubble’s images were compiled into a little movie of the journey; each frame comprises about 30 to 50 minutes and captures the comet spinning “like a lawn sprinkler,” The Christian Science Monitor noted.

Comets are made of frozen material, including gas, rocks, and dust and when this material warms up, it glows. The center of the celestial bodies is called the nucleus, which is generally about six miles wide. When it vaporizes on the comet’s approach to the sun, it can stretch to 50,000 miles.

The nucleus of 252P was less than one miles across and scientists believe that it’s the nucleus that is spinning in the images. According to Discovery, the spinning wasn’t spotted until the images were seen together, capturing water vapor “blasting” from the center and sending dust out into space.

The bright light that results appears to rotate, like a lighthouse beam, as the Post described it. The nucleus spins and the jet of water vapor sweeps around it in a tail, lit up by sunlight. Though the comet’s rotating vapors were captured by Hubble, its relatively small nucleus was not.

However, the rate of the tail spin can reveal the spin of the nucleus and therefore provide information about the comet’s history and how many volatile materials it contains.

Comet 252P is now flying away from the Earth and it’s already 25 million miles away. It will return to the inner solar system in five years, but it will never fly as close as it did this year.

The comet is 4.5 billion years old, a relic from the days our solar system was formed. It was discovered in 2000 by MIT’s Lincoln Near Earth Asteroid Research (LINEAR) survey. The little sister that passed Earth, and evaded Hubble’s camera, passed by the day after and likely broke off 252P long ago. BA14 could’ve been ripped off 252P and then kept trailing along behind it.

To explain how these two comets could be related, scientists are turning to Jupiter. In 1994, Comet Shoemaker-Levy 9 and 21 pieces of debris battered the planet. Astronomers think Jupiter’s gravitational force pulled the comet apart during a previous pass by, two years prior.

This could’ve happened to 252P during a previous pass through the inner solar system, perhaps even a fly-by of Jupiter. Smaller pieces may also be trailing behind.

The last time the Earth was visited by an impressive comet was 1770. It was called Lexell and soared to within 1.4 million miles of Earth. Reports at the time described a head four times wider than the moon and as bright as the night sky’s brightest stars.

[Photo By ESA & Hubble / Wikimedia Commons]

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