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https://www.space.com/dart-asteroid-impact-debris-tail-photo

After DART crash, asteroid Dimorphos sports a tail of debris thousands
of miles long
By Robert Lea published about 3 hours ago
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bright patch at center of image with long bright line to the right
The aftermath of the DART collision with the asteroid Dimorphos as seen
by SOAR Telescope. (Image credit: NOIRLab)

A new stunning image shows that two days after NASA's Double Asteroid
Redirection Test (DART) spacecraft slammed into the asteroid Dimorphos,
the space rock had grown a tail of glowing debris extending thousands of
miles.

The comet-like tail is made of dust and debris was blasted from the
surface of Dimorphos, part of a double asteroid system, by the
intentional impact of DART, the first mission designed to test whether
such a collision could divert a hypothetical asteroid threatening to hit
Earth. Dimorphos' new tail was imaged by astronomers Teddy Kareta from
the Lowell Observatory and Matthew Knight from the U.S. Naval Academy
using the 4.1-meter Southern Astrophysical Research (SOAR) Telescope, at
the National Science Foundation-funded NOIRLab's Cerro Tololo
Inter-American Observatory in Chile.

"It is amazing how clearly we were able to capture the structure and
extent of the aftermath in the days following the impact," Kareta said
in a statement(opens in new tab).

Related: Here's the last thing NASA's DART spacecraft saw before it crashed

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Observing the ejected material could allow scientists to better
determine the nature of the surface of Dimorphos by revealing just how
much material the collision with DART ejected, the speed at which the
material was launched and the size of the ejected particles. This
knowledge could ultimately help space agencies like NASA protect Earth
from asteroid impacts because a better understanding of asteroid
structure and composition helps scientists model how best to divert them.

The material in the dust trail was initially ejected on Sept. 26 when
DART hit Dimorphos, forming a cloud around the asteroid. The tail-like
structure formed when radiation pressure from the sun pushed the debris
away from the body of the asteroid, just as happens with the tails of
comets as they approach the sun from the distant reaches of the solar
system.

The SOAR image shows Dimorphos' new feature extending from the center of
the image to the right-hand edge of the image. Using Dimorphos' distance
from Earth at the time the image was captured, the astronomers estimated
the tail was around 6,200 miles (10,000 kilometers) long. (Before the
impact, scientists estimated that Dimorphos itself was about 525 feet,
or 160 meters, wide.)

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SOAR will continue to observe the aftermath of the DART impact,
collecting data that will help researchers assess how successful this
attempt to modify the orbit of an asteroid has been. SOAR is a key
member of the Astronomical Event Observatory Network (AEON) of
telescopes, which is dedicated to nimbly following up on reports of new
astronomical phenomena.

"Now begins the next phase of work for the DART team as they analyze
their data and observations by our team and other observers around the
world who shared in studying this exciting event," Knight said. "We plan
to use SOAR to monitor the ejecta in the coming weeks and months. The
combination of SOAR and AEON is just what we need for efficient
follow-up of evolving events like this one."

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Robert Lea
Robert Lea
Contributing Writer
Robert Lea is a science journalist in the U.K. whose articles have been
published in Physics World, New Scientist, Astronomy Magazine, All About
Space, Newsweek and ZME Science. He also writes about science
communication for Elsevier and the European Journal of Physics. Rob
holds a bachelor of science degree in physics and astronomy from the
U.K.’s Open University. Follow him on Twitter @sciencef1rst.