In Photos: 167 Miles Wide ‘Dog Bone’-Shaped Asteroid Snapped By Scientists

By Jamie Carter, Contributor
This image provides a size comparison of the asteroid Kleopatra with Chile.  The top half of the image shows a computer model of Kleopatra, a “dog-bone” shaped asteroid which orbits the Sun in the Asteroid Belt between Mars and Jupiter. End to end, Kleopatra is 270 kilometres long.  The bottom half of the image gives an aerial view of Chile, with the footprint Kleopatra would have if it were hovering above the country.  ESO/M. Kornmesser/Marchis et al.

Astronomers have snapped the best photos yet of “Kleopatra,” an asteroid measuring 167 miles/270 kilometers in diameter—and which resembles a dog bone.

Calling it a “weird outlier,” the team—whose papers are published today in Astronomy & Astrophysics—also imaged and examined Kleopatra’s two moons, most likely the product of an ancient, violent collision.

Here are seven things to know about Kleopatra:

This processed image, based on observations taken in July 2017, shows the two moons of the asteroid Kleopatra (the central white object), AlexHelios and CleoSelene, which appear as two small white dots in the top-right and bottom-left corners of the picture. Kleopatra’s moons are difficult to see in the raw images — which were taken with the Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) instrument on ESO’s VLT — owing to glare around the asteroid, inherent to this kind of adaptive-optics observations. To achieve this view, the images of Kleopatra have been processed to remove the glare and reveal the moons.  ESO/Vernazza, Marchis et al./MIS

1. It has twin moons

Asteroids can have moons? Sure. Back in 1993 NASA’s Galileo spacecraft noticed the first moon orbiting the asteroid 243 Ida in the asteroid belt and astronomers have been noticing them ever since. It’s thought that the most likely way for an asteroid to get a moon or two is after a collision with another asteroid.

Kleopatra’s moons, called Cleoselene and Alexhelios after the twin children of the Egyptian queen, were found in 2008. One of the papers published today confirms their exact orbits for the first time.

These eleven images are of the asteroid Kleopatra, viewed at different angles as it rotates. The images were taken at different times between 2017 and 2019 with the Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) instrument on ESO’s VLT.  Kleopatra orbits the Sun in the Asteroid Belt between Mars and Jupiter. Astronomers have called it a “dog-bone asteroid” ever since radar observations around 20 years ago revealed it has two lobes connected by a thick “neck”. ESO/Vernazza, Marchis et al./MIS

2. It’s a unique and weird outlier

“Kleopatra is truly a unique body in our Solar System,” said Franck Marchis, an astronomer at the SETI Institute in Mountain View, USA and at the Laboratoire d'Astrophysique de Marseille, France, who led one of the studies.

“Science makes a lot of progress thanks to the study of weird outliers. I think Kleopatra is one of those and understanding this complex, multiple asteroid system can help us learn more about our Solar System,” he added.

3. It lives in the Main Asteroid belt

Officially called 216 Kleopatra, this huge asteroid orbits the Sun in the Main Asteroid Belt between Mars and Jupiter. It’s about 124 million miles/200 million kilometres away from Earth at its closest. It will never hit Earth.

These eleven images are of the asteroid Kleopatra, viewed at different angles as it rotates. The images were taken at different times between 2017 and 2019 with the Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) instrument on ESO’s VLT.  Kleopatra orbits the Sun in the Asteroid Belt between Mars and Jupiter. Astronomers have called it a “dog-bone asteroid” ever since radar observations around 20 years ago revealed it has two lobes connected by a thick “neck”. ESO/Vernazza, Marchis et al./MIS

4. It’s made of pebbles

Mostly a pile of metal, possibly a nickel-iron alloy rubble, Marchis was one of the scientists who used the W.M. Keck II telescope to discover back in 2011 that Kleopatra is 30-50% empty space.

The second paper published today indicates that Kleopatra is made up of loose “pebbles” that may have formed its two moons.

5. It was first found in 1880

No—this is not an asteroid that’s new to science. Kleopatra was first discovered in 1880, but not until 2000 did its odd shape become obvious when NASA astronomers imaged it using the now dead Arecibo Observatory in Puerto Rico to bounce radar signals off it.

6. It’s shaped like a ‘dog bone’

That 2000 study found that Kleopatra has two lobes connected by a thick “neck,” and it’s since been referred to as the “dog-bone asteroid.”

7. It’s 167 miles long

Marchis’ study, using the European Southern Observatory’s Very Large Telescope (ESO’s VLT) in the Atacama Desert in Chile to take photos between 2017 and 2019, found that Kleopatra one of the lobes to be larger than the other, and determined the length of the asteroid to be about 167 miles/270 kilometers.

Wishing you clear skies and wide eyes.


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