A storm
from the sun ripped a tail off a comet, and a NASA satellite captured the whole
event.
The
spectacular cosmic crash occurred on April 20 when the sun cast out a coronal
mass ejection (CME), or large cloud of magnetized gas. The tempest was
thrust directly in the path of Comet Encke,
which was traveling around the sun, within the orbit of Mercury. As the gas
swept over the comet, its tail brightened and then was separated completely
from its parent icy rock and carried away.
NASA's pair
of Solar Terrestrial Relations Observatory (STEREO) satellites captured the
whole incident in newly released images
and video.
"We
were awestruck when we saw these images," said Angelos Vourlidas of the
Naval Research Laboratory. "This is the first time we've witnessed a
collision between a coronal mass ejection and a comet, and the surprise of
seeing the disconnection of the tail was the icing on the cake."
Comets are
icy leftovers from the solar system's formation billions of years ago. They
occasionally detour from their home in the cold, distant regions of the solar
system, after a gravitational tug from a planet or another comet sends them
into the inner solar system.
The sun's
heat vaporizes gas and dust from the ice core of the comet, forming its tail.
CMEs are
violent eruptions on the sun, with masses upwards of a few billion tons
traveling anywhere from 62 to 1,864 miles per second (100 to 3,000 kilometers
per second). They can cause geomagnetic
storms in the Earth's atmosphere, which can disrupt satellite and radio
communications and sometimes disable satellites.
While
scientists were aware that a comet's tail would occasionally completely
disconnect and suspected CMEs were the culprit, this is the first observation
of the violent event.
The NASA
observations are detailed in the Oct. 10 issue of Atmospheric Journal
Letters.
Another
study announced today showed comets can sometimes slow
the solar wind down, too.
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