Sedna

First pictures of Sedna, the most distant known planetoid in the solar system.

8 billion miles from our little blue dot is the planet Sedna, making its residence within the Oort Cloud. Sedna is currently the furthest known object in the solar system, aside from the icy comets that also call the Oort Cloud their home. It was discovered in November of 2003 by Michael Brown, Chad Trujillo, and David Rabinowitz when it was close to perihelion at 86 AU, but has a highly elliptical orbit that reaches an estimated 937 AU. It will reach its perihelion in about 70 years, at which time it will start to move away from us. It was lucky for us to catch it when it was so close as it has a 10,000 earth-year year, and we still have plenty of time to study it before it is beyond our reach again.  Designated as a dwarf planet, it is only 1,100 miles in diameter, just slightly less than Pluto but 8-10 times less than Earth, and red.

Its discovery, along with Quaoar and Eris helped to spark a debate within the International Astronomical Union which ended up narrowing  the definition for a classical planet in 2006. They came away with requirements for classical planets being: They must orbit the Sun solely, have a mass that is large enough to be nearly round, and have cleared all debris from its orbit.

The discovery is strong evidence for the existence of the Oort Cloud. Namely its orbital pattern. The pattern is unlike the known solar system, but it syncs up to what predicted objects within the Oort Cloud would be like. Because of the distance from the sun, the gravity it is bound to is fairly weak, and prone to fluctuations from outside influences. Much like comets that come from the Cloud are pushed by closely passing bodies, one may have elongated the orbit of Sedna this way.


Clavin, W. (2004). Planet-Like Body Discovered at Fringes of Our Solar System. Retrieved from http://www.nasa.gov/vision/universe/solarsystem/planet_like_body.html

Howell, E. (2014). Sedna: Possible Dwarf Planet Far From the Sun. Retrieved from http://www.space.com/25695-sedna-dwarf-planet.html

 Jet Propulsion Laboratory: California Institute of Technology. (2015). JPL Small-Body Database Browser. Retrieved from http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=Sedna

OP

The Oort Cloud is a very special place in the Solar System. For the most part, the different parts that make up the Solar System all fall onto or near the orbital plane. This is true for all objects, comets, asteroids, planets, etc. until you get to the Oort Cloud. This shell is located far away from any of the planets, starting at about 2,000 Au and continuing to over 100,000 Au away. It is thought that the material that makes up the cloud is the left over debris from the protoplanetary disk. As such, it was formed much closer to Sol then where it rests now, but due to gravitational influences in the inner solar system, many were flung to where they rest now.  Everything that is within the Oort Cloud is very cold and very old, with a large majority of it dating back to the formation of the solar system. As the objects  within the Oort Cloud are very far from the Sun, it is very hard to see any of the actual objects inside of it and as such have only been able to calculate its realness through mathematical calculations that insist that it must be there.

The Oort Cloud surrounds the Solar System like a shell.

The Oort Cloud is a major object that needs to be studied, and as it is studied there are more bodies within the cloud that are worth mention. As we take a closer look next time we will look at one of the largest objects within the cloud, the planetoid Sedna.

 Space Facts. (2015). Space Facts. Retrieved from http://space-facts.com/oort-cloud/