Sedna was named after the Inuit goddess Sedna who created the sea creatures of the Arctic Ocean. It is the coldest most distant place known in the solar system. She has a high albedo and very red-Reddish object after mars. The temperature never rises above -240 celsius (-400 degrees Fahrenheit). Just like Eris it was discovered by Dr. Mike Brown, Drs. Chad Trujillo , and David Rabinowitz.
Sedna is suggested to be formed near the sun, in region between Jupiter and Neptune. It may have an gravitational encounters with other bodies causing it to launched in its current orbit. However, the trouble is that she never comes closer than about twice the distance of Pluto. It could be related to the hypothesized Oort cloud, but its 10x closer than the predicted distance of the Oort cloud. The Oort cloud is an immense spherical cloud surrounding the planetary system and extending approximately 3 light years, about 30 trillion kilometers from the Sun. This vast distance is considered the edge of the Sun's orb of physical, gravitational, or dynamical influence.
Brown speculated that this "inner Oort cloud" might have been formed billions of years ago when a rogue star passed by the sun, nudging some of the comet-like bodies inward."
Sedna (2003 VB12) diameter is 800 - 1100 miles, less than 1,700 km ( about 1,00 miles). It's mass is unknown and the bulk density is also unknown, probably about 2 grams per cubic centimeter making it roughly half rock and half ice. Its orbit is highly elliptical with an orbital period of 11,249 years. The average orbital radius is 525.6 AU ( semi-major axis), orbital eccentricity is 0.855, and orbital inclination is 11.9 degrees - 12 degrees, less Pluto's. The rotational period of Sedna is about 20 days or so, but no longer than 50 days. Sedna's Axial period is 10 hours, Perihelion is 76.0 AU, and Aphelion is 928 AU.
Sedna had our astronomers baffled with its mystery self. Sedna rotates slowly, which causes astronomers like Mike Brown to think it has a moon. However, with NASA's Hubble Space Telescope, it shows that Sedna stands alone with only faint background of the stars around it. "I'm completely baffled at the absence of a moon," Brown said. "This is outside the realm of expectation and makes Sedna even more interesting. But I simply don't know what it means.
There are four possibilities for why we can not see Sedna's moon. The first reason is that the moon may be behind Sedna and we could not see it. The chances of this happening is 1 in a 100 chances, but it can not be ruled out yet. Second reason is perhaps the moon is fainter than what we exspected. Third reason is perhaps there is no moon. It is possible that there was once a moon, but it may have gotten knocked out by another passing object or it's time just ran out. The last possibable reason is that perhaps our evidence is misleading us. Either the brightening and dimming that we think we see are not real or the measurement is real, but we are being fooled. Before we can determine if Sedna really have a moon or not, We need to careful look at the rotation of Sedna next year.