Recent observations show that there may be a large planet at the edge of the solar system which causes comets in the Oort Cloud to enter the solar system and its orbit may correlate with the mass extinctions on Earth.
There are several groups of scientists who believe that there is a massive object just beyond the edge of our solar system that causes comets to enter the planetary region. Observations and calculations have been ongoing for decades, yet many scientists feel that there is not an above average occurrence of comet entries in the solar system from the Oort Cloud.
Some scientists suggest that our sun may have a companion that disturbs comets from the edge of the solar system that is a giant planet with up to four times the mass of Jupiter. Other scientists have long conjectured that a hidden star, a red or brown dwarf, that they call “Nemesis” may orbit the solar system about 1 light-year away.
Diagram showing the position of the Oort Cloud.
Southwest Research Institute
A NASA space telescope launched in 2009 may soon detect a hidden companion to our sun inside the Oort cloud. This cloud surrounds our solar system with billions of icy objects and where comets reside until they are bumped out of this stable region from comet-to-comet collisions or gravitational forces from larger objects.
A massive Jupiter-like planet would be difficult to spot since it would be extremely cold, roughly minus 100 degrees F, and receive little if any light from the sun. It could be found up to 30,000 astronomical units from the sun. (1 AU is the distance between the Earth and the sun, about 93 million miles,150 million km).
Most systems with stars like our sun, called class G stars, have companions. Only about one-third are single-star systems like our solar system.
Scientists have already proposed that a hidden star, which they call "Nemesis," might lurk a light-year or so away from our sun. They suggest that during its orbit, this red dwarf or brown dwarf star would regularly enter the Oort cloud, altering the orbits of many comets there and causing some to fall toward the inner solar system. They suspect that this may provide an explanation for what seems to be a cycle of mass extinctions on Earth.
Other astronomers have calculated that if Nemesis did exist, its orbit could not be nearly as stable as claimed. A group of researchers point to evidence that our sun might have a different sort of companion.
To avoid confusion with the Nemesis model, astrophysicists John Matese and Daniel Whitmire at the University of Louisiana at Lafayette dub their extrasolar object "Tyche" which is the good sister of the goddess Nemesis in Greek mythology, and a name proposed by scientists working on NASA's Wide-Field Infrared Survey Explorer (WISE) space telescope.
It is the WISE observatory that has the best chance of having spotted Tyche, if this companion to the sun exists at all.
Two centuries of observations have indicated an anomaly that suggests the existence of Tyche, Matese said. "The probability that it could be caused by a statistical fluke has remained very small," he added.
The pull of Tyche might also explain why the dwarf planet Sedna has such an unusually elongated orbit. Sedna was discovered in 2003 and ranges from 76 to 1000 AU. Another dwarf planet Quaoar is about 4 billion miles away from Earth, well over a billion miles farther away than Pluto. Unlike Pluto, its orbit around the Sun is very circular, even more so than most of the planetary-class bodies in the solar system.
Orbit of Sedna – the purple ring is Pluto’s orbit
Many planetary scientists expect the undiscovered companion to be the size of Neptune or smaller. Very few anticipate the discovery of a Jupiter-sized object. If a large object is found scientists will then have to determine how it got there and may alter our understanding of how planets were formed in the early solar system.
Where is Tyche?
Tyche's existence is questionable since the patterns seen in the outer Oort cloud is not seen in the inner Oort. Scientists expect the patterns to correlate, but they do not.
The WISE team may have caught evidence for Tyche twice before the space observatory's original mission ended in October 2010. There could be enough data to corroborate the object's existence within a few months as researchers analyze WISE's data. If WISE detected signs of Tyche only once, or not at all, researchers would have to wait several years for other telescopes to be launched to confirm or deny the existence of a solar companion.