Tyche (//) is the nickname given to a possible gas giant planet in the Solar System's Oort cloud. It was first proposed in 1999 by astronomer John Matese of the University of Louisiana at Lafayette.   Matese and Daniel Whitmire say that the points of origin for long-period comets gives a pattern that suggests Tyche's existence. They noted that Tyche, if it exists, should be seen in the archive of data that was collected by NASA's Wide-field Infrared Survey Explorer (WISE) telescope. However, several astronomers disagree that Tyche exists. It will take two years to look over the WISE data learn if WISE has actually found such a world or not.
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- Wolchover, Natalie (February 15, 2011). "Article: Astronomers Doubt Giant Planet 'Tyche' Exists in Our Solar System". Space.com. http://www.space.com/10863-mystery-planet-tyche-debate.html. Retrieved February 15, 2011.
- Matese, John J.; Whitmire, Daniel P. (2011). "Persistent evidence of a jovian mass solar companion in the Oort cloud" (PDF). Icarus 211 (2): 926–938. doi:10.1016/j.icarus.2010.11.009. http://arxiv.org/PS_cache/arxiv/pdf/1004/1004.4584v1.pdf.
- Plait, Phil (February 14, 2011). "No, there’s no proof of a giant planet in the outer Solar System". Discovery Magazine. http://blogs.discovermagazine.com/badastronomy/2011/02/14/no-theres-no-proof-of-a-giant-planet-in-the-outer-solar-system/#more-28256. Retrieved February 15, 2011.
- Whitney Clavin (2011-02-18). "Can WISE Find the Hypothetical 'Tyche'?". NASA/JPL. http://www.jpl.nasa.gov/news/news.cfm?release=2011-060. Retrieved 2011-02-19.