Discovering Sedna: The Mysterious Red Planetoid Orbiting the Sun

[Orion1]

The discovery of red and shiny Sedna, a "planetoid" of rock and ice between 800 miles and 1,100 miles in diameter, or about three-quarters the size of Pluto, was announced by Mike Brown, an astronomer at the California Institute of Technology who led the NASA-funded team that found it.

Sedna is the largest object found orbiting the sun since the discovery of Pluto, the ninth planet, in 1930. It trumps in size another object, called Quaoar, discovered by the same team in 2002.

The scientists estimate the temperature on Sedna never rises above 400 degrees below zero Fahrenheit, making it the coldest known body in the solar system.

Sedna follows a highly elliptical path around the sun, a circuit that it takes 10,500 years to complete. It is relatively close to the sun now, but loops out as far as 84 billion miles from the sun at its farthest point, or 900 times the distance between the sun and Earth.

There is indirect evidence a tiny moon may trail Sedna, which is redder than all other known solar system bodies except Mars.

It may have a small moon circling in a 40-day orbit.

Name: Sedna (VB12)
Class: Kuiper Planetoid
Period: 10,500 years
Semi-major axis: 532 AU
Eccentricity: 0.857
Inclination: 11.9 deg
Perihelion: 76 AU
Diameter: 800-1,100 miles (1287.475-1770.278 km)
Temperature: -400 degrees Fahrenheit (68.706 Kelvin)
Moon period? (Arctica): 40 days?

Reference:
http://www.sltrib.com/2004/Mar/03162004/nation_w/148348.asp
http://www.gps.caltech.edu/~chad/quaoar/
http://www.space.com/images/h_sedna_compare_02.jpg
http://www.space.com/images/h_sedna_orbit_02.jpg
http://www.space.com/images/h_sedna_artist_02,0.jpg
http://www.hohmanntransfer.com/mn/0403/03vb12-031114-675.gif
http://www.space.com/images/H_oort.cloud_02,0.jpg
http://www.space.com/scienceastronomy/sedna_earth_040316.html

 

[davenn]

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