Astronomers watched in awe as binary asteroid Didymos brightened up immediately after the impact of NASA's DART spacecraft on Monday (Sept. 26).
Italian astronomer Gianluca Masi couldn't contain his excitement at the sight as he shared the observations in a livestream via the Virtual Telescope project. A small, dim dot that marked the Didymos-Dimorphos binary asteroid, at that time some 7 million miles (11 million kilometers) from Earth, began rapidly brightening and within minutes outshined even the brightest of stars in that tiny section of the sky.
"This is exceeding my expectations a lot," Masi said in the stream. "The object is now nearly 3 magnitudes brighter than earlier, this is tens of times more!"
Since Italy was outside of the region with a direct view of Didymos at the time of the collision, Masi viewed the asteroid via a 12-inch (30 centimeters) telescope at South Africa's Klein Karoo Observatory in a feed shared by amateur astronomer Berto Monard.
The two astronomers watched in awe as Didymos not only brightened up, but also grew in size and changed shape as the cloud of debris stirred by DART's impact quickly spread in the surrounding space.
"Soon after the impact, an amount of dust was released like a plume and now this cloud of dust is expanding, sending back light from the sun," Monard explained in the stream. "This is much more than what I could expect. Even the shape is a bit different. It's like a comet. There are particles that are moving away from the asteroid and that's why you have a bigger halo of light."
Masi added that the only other time astronomers could observe such a human-made brightening of a celestial object was in 2005 when NASA's Deep Impact probe intentionally collided with Comet Tempel 1. The goal of that mission, however, wasn't to change the comet's trajectory but to extract some material from its surface to enable scientists to learn more about the composition of these ice balls.
"At that time, I could record a brightness increase, but I have to say that this is by far much more dramatic," Masi commented on his observations of Deep Impact's encounter with the comet.
Telescopes all over the world are currently aiming at the Didymos binary asteroid hoping to learn all they can about the cloud of debris stirred by DART's impact and about the effects the collision had on the orbit of the 560-foot-wide (170 meters) moonlet Dimorphos around the 2,560-foot-wide (780 m) main asteroid Didymos. Altering Dimorphos' orbit around Didymos by at least 73 seconds was the primary purpose of the DART mission.
If last night's impact was successful, the DART experiment could lead to technology that humankind might need one day to protect itself from a space rock on a collision course with Earth.