A tiny pebble could have caused the dramatic self-destruction of a 5-mile-long asteroid

asteroid gault yorp effect 6478
The asteroid 6478 Gault is seen with the NASA/ESA Hubble Space Telescope, showing two narrow, comet-like tails of debris that tell us that the asteroid is slowly undergoing self-destruction. The bright streaks surrounding the asteroid are background stars. The Gault asteroid is located 214 million miles from the Sun, between the orbits of Mars and Jupiter. NASA, ESA, NASA, ESA, K. Meech and J. Kleyna (University of Hawaii), O. Hainaut (European Southern Observatory), L. Calçada

Hubble has observed something unusual in the sky — a self-destructing asteroid called 6478 Gault, or simply Gault for short. But what caused it?

The Gault asteroid, named after planetary geologist Donald Gault, is between four and nine kilometers long (that’s 2.5 to 5.6 miles) and has a distinctive double tail. The two comet-like tails of debris are evidence of activity in which the asteroid is ejecting material into space, suggesting that Gault is breaking apart.

The asteroid is disintegrating due to a process called YORP torque (short for the Yarkovsky–O’Keefe–Radzievskii–Paddack effect) which is caused by the scattering of solar radiation. Sunlight hits the asteroid and heats it, producing infrared radiation which is sent out into space and which carries heat and momentum with it. This creates a force which in rare cases can make an asteroid spin faster.

As the asteroid spins faster and faster, the centrifugal force pulling the asteroid apart eventually becomes more powerful than the gravitational force holding it together. When this happens, rocks and dust are pulled off the surface of the asteroid and create a tail of debris.

“This self-destruction event is rare,” Olivier Hainaut of the European Southern Observatory, Germany, explained in a statement. Of the 800,000 asteroids in the belt between Mars and Jupiter, astronomers estimate that only one YORP disruption is seen per year.

But Hubble and other new telescopes are now able to view these wild asteroids as they disintegrate. “Active and unstable asteroids such as Gault are only now being detected by means of new survey telescopes that scan the entire sky,” Hainaut said, “which means asteroids such as Gault that are misbehaving cannot escape detection any more.”

Gault is important not only because it is rare to see a YORP event in action but also because it is believed to have a rotation period of two hours, which is right on the border of the speed required for the YORP effect to kick in. “Gault is the best ‘smoking-gun’ example of a fast rotator right at the two-hour limit,” lead author Jan Kleyna of the University of Hawaiʻi, confirmed in the statement. “It could have been on the brink of instability for 10 million years. Even a tiny disturbance, like a small impact from a pebble, might have triggered the recent outbursts.”

One tiny pebble, eh?

The findings will be published in The Astrophysical Journal Letters.

Emerging Tech

Awesome Tech You Can’t Buy Yet: Robots that eat landmines and clean your floors

Check out our roundup of the best new crowdfunding projects and product announcements that hit the web this week. You may not be able to buy this stuff yet, but it's fun to gawk!
Emerging Tech

Gravitational forces at heart of Milky Way shaped this star cluster like a comet

Hubble has captured the stunning Messier 62 cluster. The cluster is warped, with a long tail which stretches out to form a shape like a comet. It is thought this distortion is due to Messier 62's proximity to the center of the galaxy.
Emerging Tech

Star gives off superflare equal to 80 billion megatonnes of TNT. That’s a lot

A tiny star the size of Jupiter has been observed giving off a massive superflare 10 times more powerful than any flare from our Sun. The findings are raising questions about how much energy small stars can hold.
Movies & TV

The best shows on Netflix right now (April 2019)

Looking for a new show to binge? Lucky for you, we've curated a list of the best shows on Netflix, whether you're a fan of outlandish anime, dramatic period pieces, or shows that leave you questioning what lies beyond.
Gaming

The best of the last generation: Our 50 favorite Xbox 360 games

The Xbox 360 thrived during a generation where games were plentiful. Here's our list of the best Xbox 360 games of all time, including all game genres and even a few special indie hits.
Emerging Tech

Happy birthday, Hubble! Telescope celebrates with image of Southern Crab Nebula

In 1990 the Hubble Space Telescope was launched into low Earth orbit, where it has remained for nearly three decades collecting information about deep space. To celebrate its birthday, Hubble imaged the beautiful Southern Crab Nebula.
Emerging Tech

The grid of the future will be powered by … giant subterranean bagpipes?

In order to transition to a more renewable-focused energy system, we need to scale up our grid storage capacity --- and our existing methods aren't going to cut it. Could compressed air be the key?
Emerging Tech

SpaceX experiences problem during test, Crew Dragon capsule may have exploded

SpaceX has experienced a problem during the testing of its Crew Dragon capsule. During the engine test firing at Cape Canaveral yesterday afternoon, an unspecified anomaly occurred which lead to plumes of smoke rising from the test site.
Emerging Tech

Beresheet crash caused by manual command, but reflector device may have survived

Details are emerging about what may have gone wrong with spacecraft Beresheet's failed moon landing. A manual command was entered which led to a chain reaction. But NASA still hopes to salvage use of its Laser Retroreflector Array device.
Emerging Tech

The oldest type of molecule in the universe has been located at last

A milestone in the development of the early universe was the combination of helium and hydrogen atoms into a molecule called helium hydride. But strangely enough, this ancient molecule has never been detected in space before now.
Emerging Tech

Mercury’s wobble as it spins reveals that it has an inner solid core

Scientists have long wondered what the inside of Mercury looks like, and they now have strong evidence that the planet has a large and solid metallic core. The data for the new findings was collected by the now-defunct MESSENGER mission.
Emerging Tech

Burgers are just the beginning: Embracing the future of lab-grown everything

You’ve almost certainly heard of the 'farm to fork' movement, but what about 'lab to table'? Welcome to the fast-evolving world of lab-grown meat. Is this the future of food as we know it?
Emerging Tech

Troubleshooting Earth

It’s no secret that humans are killing the planet. Some say it’s actually so bad that we’re hurtling toward a sixth major extinction event -- one which we ourselves are causing. But can technology help us undo the damage we’ve…
Emerging Tech

Inside the Ocean Cleanup’s ambitious plan to rid the ocean of plastic waste

In 2013, Boyan Slat crowdfunded $2.2 million to fund the Ocean Cleanup, a nonprofit organization that builds big, floating trash collectors and sets them out to sea, where they’re designed to autonomously gobble up garbage.