Pair of Dwarf Planets May Lurk Beyond Pluto

At least two unknown dwarf planets may be lurking beyond Pluto, orbiting around the Sun in our own solar system just waiting to be discovered, according to a new study.

This comes from an analysis of objects observed beyond Neptune, called extreme trans-Neptunian objects (ETNO), which normally should be flying around randomly in space, but in this case show some unusual symmetry.

"This excess of objects with unexpected orbital parameters makes us believe that some invisible forces are altering the distribution of the orbital elements of the ETNO," Carlos de la Fuente Marcos, with the Complutense University of Madrid, said in a press release.

"We consider that the most probable explanation is that other unknown planets exist beyond Neptune and Pluto," he added.

According to conventional theory, there is a certain set of characteristics that ETNO orbits must fulfill. For example, they should have a semi-major axis, or average distance from the Sun, of about 150 astronomical units (AU). (1 AU is the distance from Earth to the Sun - roughly 93 million miles, or 150 million kilometers.) These orbits should also have an inclination, relative to the plane of the solar system, of almost 0 degrees.

However, the actual orbits of the 13 ETNOs studied are quite different, with semi-major axes ranging from 150 to 525 AU and average inclinations of about 20 degrees.

"The exact number is uncertain, given that the data that we have is limited, but our calculations suggest that there are at least two planets, and probably more, within the confines of our solar system," Marcos said.

The new results are detailed in two papers in the journal Monthly Notices of the Royal Astronomical Society.

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