Touched by the sun, oddball asteroid crumbles before our very eyes

he NASA/ESA Hubble Space Telescope photographed the break-up of P/2013 R3 from Oct. 29, 2013 to Jan. 14, 2014. Although fragile comet nuclei have been seen to fall apart as they approach the Sun, nothing like this breakup, which occurred in the asteroid belt, has ever been observed before. Click to enlarge. Credit: NASA/ESA/D. Jewitt (UCLA)

The Hubble Space Telescope has photographed a never-seen-before breakup of an asteroid. Named P/2013 R3 (Catalina-PanSTARRS), it was discovered last September 15 by the Catalina and Pan-STARRS sky surveys as a faint, slightly fuzzy object. Two weeks later, the giant Keck Telescope in Hawaii took a closer look and saw not one but three separate pieces cruising along convoy-style in a dust cloud of their own making.

Animation showing the break up of P/2013 R3

By December it had crumbled into ten pieces, the four largest of which measure about 650 feet (200 meters) across or nearly two football fields apiece. The Hubble data show the fragments are drifting apart at the leisurely rate of just under 1 mile per hour (1.5 km/hr) or about the speed of someone walking while texting.


P/2013 R3 on Oct. 22, 2013 looked very much like a comet. The individual pieces that comprise the shattered asteroid are too small to resolve in this photo. The fresh dust exposed as the asteroid fell apart shows as a faint tail. Credit: Damian Peach

Astronomers have ruled out a collision, which would have happened suddenly and sent pieces flying apart at much great speeds. Shattering from the pressure of vaporizing ices in its interior also seems unlikely given the asteroid’s distance of 298 million miles (480 million km) from the sun –  believed too cold for any ice it might possess to suddenly turn to vapor and pry the body apart. Besides, if it did contain ice, P/2013 R3 wouldn’t be considered an asteroid anymore but a main belt comet, an asteroid-like object between Mars and Jupiter that occasionally flares up as a comet.

So what could be responsible for perpetrating killing off an asteroid? Scientists suspect it was YORP up to his old tricks. YORP or the Yarkovsky-O‘Keefe-Radzievskii-Paddack effect requires only the light touch of sunshine to get rolling.

This illustration shows one possible explanation for the disintegration of asteroid P/2013 R3. Sunlight absorbed unequally across the asteroid’s surface can spin up its rotation and cause it to fall apart. More details on how this happens below. Credit: NASA, ESA, D. Jewitt (UCLA), and A. Feild (STScI)

Sunlight absorbed by P/2013 R3 is re-emitted as heat. Assuming the asteroid is irregular in shape – and most are because they’re so small – some areas get hotter and give off more heat than others. The imbalance causes a torque on the asteroid, increasing its spin rate.

Hubble Space Telescope close up of P/2013 R3 breaking up as seen on Nov. 15, 2013. Although fragile comet nuclei have been observed to fall apart as they approach the sun, this is the first time an asteroid has been seen to do so. Click to enlarge. Credit: NASA/ESA/D. Jewitt (UCLA)

Many asteroids are “rubble piles” of individual objects held together by gravity rather than solid rocks. Collisions with other asteroids over the 4.5 billion year lifetime of the solar system have shattered and pulverized their interiors. Primed to fall apart, the spin-up from YORP causes the asteroid to come apart at the seams. Pieces that were loosely-bound can drift away due to centrifugal forces; fresh dust exposed creates an enveloping comet-like cloud of debris. Pretty darn cool.

Yorping the day away. Illustration showing how sunlight absorbed unevenly by an asteroid’s surface creates torque that can increase its spin rate. Illustration: Bob King

We’ve seen one other instance of an asteroid breaking to pieces when Hubble photographed the aftermath of a head-on collision between the peculiar comet-like asteroid P/2010 A2 and a smaller asteroid in January 2010. But this is the first time ever we’ve watched an asteroid fall apart of its own accord.

“This indicates that the Sun may play a large role in disintegrating these small Solar System bodies, by putting pressure on them via sunlight,” said Agarwal.

Much of P/2013’s debris, weighing in at around 200,000 tons, will spiral its way into into the sun, but a portion could one day light up Earth’s skies as a lovely meteor shower. Amazing isn’t it how nature shares its incredible stories when we pay attention.

7 Responses

  1. Steven

    Or, it’s an extraterrestrial self-replicating probe scooping up raw materials in order to self replicate! No, but it’s probably YORP.

  2. Paul

    Astrobob, I cannot accept the official explanation and I hope you will indulge me a little. Now this is the third unprecidented event we’ve seen in the asteroid belt in so many months. First, the six-tailed asteroid, then water vapor (or more likely ozone [O3]) around Ceres, and now this – another asteroid behaving more like a comet. I don’t know if we’ll get anymore photos, but my prediction is that every visible fragment of this asteroid will desintigrate into dust and small pieces just like, say, Ison did when it went around the sun. In fact, we already see this taking place in the photos provided. I’m not sure how you feel about the electric universe theory, particulary The Electric Comet Full documentary (I know it is hotly contested) but my contention is that something is heavily ionizing objects in the asteroid belt, drawing solar flares from the sun to them, and then picking away at them through electrical arcing on the surfaces until they form single or multiple tails. had to post it

    1. Profile photo of astrobob

      Hi Paul,
      Brave man. You’re welcome to your opinion about the EC idea, but unfortunately there’s no evidence to support this happening. The clouds of material that leave the sun, while composed of ionized electrons and protons, are in sum total neutral. The flares themselves do not travel – they propel the high speed clouds into space.

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