Sedna

Discovered in 2003, Sedna has a highly elliptical orbit that takes it from 76 astronomical units (AU) at its closest approach to the sun to 937 AU at its farthest, taking about 11,400 years to complete its orbit.

Sedna's diameter is estimated to be around 1,000 kilometers, similar in size to Ceres and Saturn's moon Tethys.

• Reddish Color: Sedna is one of the reddest objects in our solar system, even redder than Mars. This is attributed to the presence of tholins, which are dark, organic compounds formed from the irradiation of simpler compounds like methane by solar ultraviolet radiation. 
• Ice Composition: While Sedna does contain ices, they are not as abundant as on Pluto and its moon Charon. Observations suggest the presence of water, methane, and nitrogen ices, but the reddish tholins are more prominent. 
• Surface Uniformity: Sedna's surface appears relatively uniform in color and spectrum, which may be due to the fact that it's located far from the sun and doesn't experience frequent impacts that could expose fresh, bright surface materials. 
• Temperature: Due to its extreme distance from the sun, Sedna's surface temperature never rises above -240 degrees Celsius (-400 degrees Fahrenheit).