Whatever you call it, Asteroid 2015 TB145 was discovered only three weeks ago – on October 10, 2015 by the University of Hawaii’s Pan-STARRS-1.
It is just over half a kilometer in diameter (600 meters) and made its closest approach to Earth today at 1 p.m. EDT. It’s distance to Earth at its closest point was 486,000 km – or about 1.3 times distance from the Earth to the Moon.
Fittingly, since today is Halloween, if you rotate the images just right the comet/asteroid does sort of look like a skull. Spooky.
The above images were created by NASA using radar data from the 305 meter Arecibo Radio Observatory in Puerto Rico. The images were captured October 30, 2015.
Astronomers have determined, primarily by examining the amount of light the object reflects, that it is likely a dead comet. That is to say it’s a comet, but over the eons it has lost its volatile materials, and so is now reasonably dark and doesn’t produce the typical sign of a comet: a tail. This is why it was initially thought to be (and named) an Asteroid.
In any event, observatories around the world are pointed at it to learn everything we can about it’s composition and orbit. It also underscores the need to keep an eye on the sky, since this is a big piece of rock, reasonably nearby in the grand scheme, and we only found it three weeks ago.
The fireball is near the equator on the left side. This image is captured from the video by “George” – the astronomer in Texas who recorded the impact on September 10, 2012 (click image to enlarge)
This story broke last night, following a report from an amateur astronomer who spotted what they thought looked like the flash from comet/meteor impact on Jupiter.
The problem is though that by the time news of this observation got out, the impact site on Jupiter had rotated out of view so no one could immediately peer through their telescopes to look for the aftermath of the impact (which usually appears as dark spots in Jupiter’s clouds).
And now it would be several hours until the impact site on Jupiter rotated back into view, so the mark left by the impact could possibly have disappeared – only large impacts leave marks that are visible for an extended period of time.
But there is an important fact not to be overlooked: Jupiter is a popular object for amateur astronomers to watch, from all over the world. Some of them (and bona-fide Observatories as well) will record their observations (using photography or video) for any number of reasons. So there was immediately a possibility that someone captured this impact live – perhaps without even realizing it.
As it turns out, that is exactly what happened:
An amateur astronomer by the name of George Hall, who lives in Dallas, caught the impact on video at about 6:30am on September 10, 2012 (time local to Dallas, TX, USA).
It’s a good thing too: this impact could have been small enough that it wouldn’t leave any visible marks for more than a few moments after impact. If George wasn’t recording, it’s possible that this fireball would have remained a rumor. Astronomers will keep their eyes on Jupiter for the next couple nights to see if they can see any dark spots from last nights impact.
This story demonstrates perfectly one of the things I love about astronomy: The word “amateur” doesn’t really mean all that much. If you have a telescope, binoculars, a pair of eyes, (or any of the above) and you record things that you see: you are an astronomer, through and through. You don’t have to work in an Observatory, or for NASA. Anyone can do it. Anyone can have a meaningful impact.
For those of you wondering about Jupiter impacts: They do happen from time to time. Jupiter is a big object, and so it has a lot of gravity and does occasionally pull things in. One of the most famous impacts on Jupiter was the comet SL-9 in 1994 (numerous giant fireballs that left visible marks on Jupiter for a couple days). Actually just a couple years ago, there was a fireball sighted similar to what happened last night. This certainly isn’t something you see every day though, so it is pretty special.
Harrison lives in Ottawa, Canada. He works in politics and is passionate about many things, including space and exploration. He's worked for a national news outlet, managing the digital products, writing news, and appearing on air to talk about science, technology, and politics. In his spare time he enjoys astronomy, scuba diving, flying airplanes, photography, and sports.