Astronomers find moon around third largest dwarf planet

James Marshall
May 23, 2017

NASA's Hubble Space Telescope (HST) which is positioned in low Earth orbit and is monitoring celestial movements has helped astronomers detecting a new moon, circling solar system's third largest dwarf planet - 2007 OR10! According to NASA, the dwarf planet's moon has lots to teach scientists about how moons formed in the early solar system-but sadly, it has no name.

The team concluded that that the planet and its moon are in the Kuiper Belt, which a realm of freezing leftovers developed by the shaping of the solar system dated 4.6 billion years ago.

Most of the Kuiper Belt's large dwarf planets - those at least 600 miles (960 km) in diameter - are now known to host moons, many of which were probably spawned by long-ago collisions.

NASA's Kepler space telescope, created to search for exoplanets, planets orbiting stars other than the Sun, found 2007 OR10 to rotate on its axis approximately once every 45 hours.

"Typical rotation periods for Kuiper Belt Objects are under 24 hours", said Csaba Kiss of the Konkoly Observatory in Budapest, Hungary.

Two images taken by Hubble, one year apart, confirmed the presence of a gravitationally bound moon around the dwarf planet. The initial investigators failed to notice the presence of the moon in the Hubble images because of its faint appearance.

The astronomers then looked to the archive images of the Hubble Space Telescope, whose Wide Field Camera 3 had captured the moon twice during two different observation runs in 2009 and 2010. The world, named 2007 OR10, is the third largest dwarf planet that we know about - around 955 miles wide. Moons around dwarf planets are elusive, though. Its distance from the Sun is about three times the distance between Pluto and Sun. Scientists believe this is due to collisions between outer Solar System objects when the system was forming more than four billion years ago.

Scientists also think that the density of these bodies could be moderate. In fact, the gravitational force was responsible with displacing these bodies out of their orbits, and offering them the ideal speed to crash and create a new object.

"This gravitational stirring may have nudged the bodies out of their orbits and increased their relative velocities, which may have resulted in collisions", Stansberry said. The speed of the colliding objects also played a key role as it could not have been too fast or too slow. It's the third or fourth largest object in the Kuiper Belt, just after Pluto, Eris, and Makemake. She studied journalism at Douglass College, Rutgers University, and earned a Graduate Certificate of Science from Swinburne University's Astronomy Online program.

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