Is There a Large Planet Orbiting Beyond Neptune?

By Keith Cowing
March 31, 2001
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TNOA comet orbiting in the most distant regions of our solar system has an orbit that isn’t where astronomers expect it to be – given the gravitational forces that are expected to govern the path of bodies in these regions. Something is apparently causing this comet’s orbit to diverge from what would otherwise be predicted.

The comet (2000 CR105) is rather large (over 400 km in diameter) and was discovered in February 2000. Its orbit is highly elliptical. 2000 CR105 is currently 53 AU away from the sun. The comet is one of perhaps 70,000 so-called “Trans Neptunian Objects” (TNOs) thought to be more or less undisturbed since their formation during the early days of the solar system. Interactions with one of the larger planets (probably Neptune) in the outer solar system led to the movement of these objects outward to much more distant orbits. Recent observations show that this comet’s orbit is much larger than previously calculated leading astronomers to suspect that another large gravitational influence is affecting the comet’s orbit – and influence that may still be exerted to the present day.

In a paper submitted to the journal Icarus, a team lead by Brett Gladman of the Observatoire de la Côte d’Azur, France, several astronomers have suggested that the planet Neptune may have once had a more eccentric orbit – one that could have allowed it to affect objects such as 2000 CR105. The team also suggests that the perturbation of 2000 CR105 could be caused by a “resident planet” of a size somewhere between our Moon and Mars that formed in these outer regions well beyond the orbit of Pluto a distance of 10 billion kilometers from the sun.

The research team posposes that 2000 CR105 may be just one example of a much larger population of TNOs that form an ‘extended scattered disk’ in the outer solar system beyond a ditsance of 38 AU.

It is important to note that the on again – off again – on again – off again Pluto-Kuiper Express mission would have studied the largest of these objects – the planet Pluto and its moon Charon – as well as other regions of the outer solar system.

Related Links

° abstract Evidence for an extended scattered disk”;
Submitted to Icarus, Mar 26/2001

° The Kuiper Belt Electronic Newsletter, SouthWest Research Institute

° The Kuiper Belt, University of Hawaii

Background Information

° Pluto-Kuiper Express Mission, NASA JPL

° NASA Reconsiders a Mission to Pluto, SpaceRef

° Pluto’s moon Charon is covered with crystalline water and ammonia Ice, SpaceRef

SpaceRef co-founder, Explorers Club Fellow, ex-NASA, Away Teams, Journalist, Space & Astrobiology, Lapsed climber.