Thursday, October 13, 2016

New Dwarf Planet Discovered in Our Solar System

Based on observations over the past three years, astronomers know that the Kuiper Belt object known as 2014 UZ224 has a highly elliptical, 1,140-year-long orbit that stretches nearly four times farther from the Sun than Pluto can ever be. NASA / JPL / Horizons

Scientists have identified a new dwarf planet in our Solar System, and it’s lurking way out in the edges, some 13.6 billion km (8.5 billion miles) from the Sun. The Iowa-sized object - for now known as 2014 UZ224 - takes 1,100 years to complete a single orbit of the Sun, and could soon join the ranks of the five established dwarf planets in the Solar System: Ceres, Eris, Haumea, Makemake, and most famous of all, Pluto.

The dwarf planet was discovered by University of Michigan astrophysicist David Gerdes with the help of a team of undergraduate researchers.

Gerdes is part of an international team of scientists working on the Dark Energy Survey — an effort to map the universe and elucidate some of its mysteries, particularly, why the expansion of the universe is accelerating. To do a dark energy survey, you need a dark energy camera, so the DES built a wide-angle camera in Cerro Tololo, Chile, that's capable of snapping images of the whole sky.

The team first spotted this object in August 2014, and then several times again in 2015 and 2016, using the 4-m Victor Blanco reflector at Cerro Tololo Inter-American Observatory in Chile. Thanks to CTIO's Dark Energy Camera, which Gerdes helped develop for DES, 2014 UZ224 stood out clearly in images despite its apparent magnitude of only 23.5.

"The same combination of survey area and depth that makes DES a state-of-the-art cosmological survey also makes it a great tool for making discoveries in our own cosmic backyard," Gerdes explains. "Our search for trans-Neptunian objects is a serendipitous by-product of the survey data." The effort has yielded dozens of Kuiper Belt objects so far, even though the team has examined only a fraction of the amassed observations. "I hope 2014 UZ224 is not the most interesting thing we eventually find!" Gerdes adds.

The discovery has now been confirmed by the International Astronomical Union, but whether or not it will decide to let 2014 UZ224 join the ranks of the five established dwarf planets in our Solar System is another matter.

Both 2014 UZ224, and the other new dwarf planet was discovered in our Solar System back in July - called 2015 RR245 - technically pass the criteria for dwarf planets, which describes an object that resembles a planet, but isn’t a planet.

The most important distinction for a dwarf planet is that it’s large enough to have become round due to its own gravitational attraction.

As notorious "Pluto killer", Mike Brown - the California Institute of Technology astronomer who successfully campaigned for Pluto to be downgraded to a dwarf planet in 2006 - explains, we can pretty much assume that anything larger than 400 km in diameter in the Kuiper belt is round, and therefore could qualify as a dwarf planet. 

2014 UZ224 is estimated to have a diameter of around 530 km (329 miles).

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