Skip to main content
  1. Home
  2. Space
  3. News

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

Georgina Torbet
By
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.

Recommended Videos

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.

Topics
Georgina Torbet
Georgina Torbet
Space Writer
Georgina is the Digital Trends space writer, covering human space exploration, planetary science, and cosmology. She…
Hubble Space Telescope is in safe mode due to a gyro problem
Hubble orbiting more than 300 miles above Earth as seen from the space shuttle.

The Hubble Space Telescope has experienced a problem with its hardware and is currently in safe mode, with science operations paused until the fault can be corrected. The problem is with one of the telescope's three operational gyros, which are used to control the direction in which the telescope points. When a fault like this is detected, the telescope automatically goes into a safe mode in which it performs only essential operations to prevent any damage to its hardware.

"The telescope automatically entered safe mode when one of its three gyroscopes gave faulty readings," NASA wrote in a statement. "The gyros measure the telescope’s turn rates and are part of the system that determines which direction the telescope is pointed. While in safe mode, science operations are suspended, and the telescope waits for new directions from the ground."

Read more
James Webb finds that rocky planets could form in extreme radiation environment
This is an artist’s impression of a young star surrounded by a protoplanetary disk in which planets are forming.

It takes a particular confluence of conditions for rocky planets like Earth to form, as not all stars in the universe are conducive to planet formation. Stars give off ultraviolet light, and the hotter the star burns, the more UV light it gives off. This radiation can be so significant that it prevents planets from forming from nearby dust and gas. However, the James Webb Space Telescope recently investigated a disk around a star that seems like it could be forming rocky planets, even though nearby massive stars are pumping out huge amounts of radiation.

The disk of material around the star, called a protoplanetary disk, is located in the Lobster Nebula, one of the most extreme environments in our galaxy. This region hosts massive stars that give off so much radiation that they can eat through a disk in as little as a million years, dispersing the material needed for planets to form. But the recently observed disk, named XUE 1, seems to be an exception.

Read more
Astronomers spot rare star system with six planets in geometric formation
Orbital geometry of HD110067: Tracing a link between two neighbour planets at regular time intervals along their orbits, creates a pattern unique to each couple. The six planets of the HD110067 system together create a mesmerising geometric pattern due to their resonance-chain.

Astronomers have discovered a rare star system in which six planets orbit around one star in an elaborate geometrical pattern due to a phenomenon called orbital resonance. Using both NASA's Transiting Exoplanet Survey Satellite (TESS) and the European Space Agency's (ESA) CHaracterising ExOPlanet Satellite (CHEOPS), the researchers have built up a picture of the beautiful, but complex HD110067 system, located 100 light-years away.

The six planets of the system orbit in a pattern whereby one planet completes three orbits while another does two, and one completes six orbits while another does one, and another does four orbits while another does three, and so one. The six planets form what is called a "resonant chain" where each is in resonance with the planets next to it.

Read more