14th November: Sedna

The dwarf planet Sedna was discovered on this date in 2003. Here are ten things you may not know about Sedna.

1. Sedna, also known as 2003 VB12 is a dwarf planet discovered by Mike Brown, Chad Trujillo, and David Rabinowitz on 14 November 2003.
2. It was, at the time, the most distant object to have been discovered in our Solar System. It's so far away that if people were ever to land on it, the sun would appear to them as no more than a bright pinpoint in the sky.
3. Because it is so far away, it's difficult to study it and come up with any definite measurements. We don't now for sure how big it is - but scientists estimate it's about 75% the size of Pluto. They also estimate that the temperature never rises above -400 degrees F. Discoverer Mike Brown has said that Sedna's position is a bit of a mystery, because it seems too far away to be affected by the sun's gravity but not far enough away to be affected by any other stars.
4. It was because of this distance that the object got its name. It was such a cold and distant world that Mike Brown suggested the name Sedna, after an Inuit goddess who lives at the bottom of the Arctic Ocean. There was a bit of a controversy in the scientific community, because he suggested the name before the object was given an official number. Nobody suggested an alternative name, and the rules were changed slightly so that if an object was deemed important enough, it could be named before it was numbered.
5. A brief word about the Sedna myth - there are numerous versions of her legend but in a nutshell, she was a beautiful Inuit girl who had many suitors but refused them all (although in some versions she ends up marrying a Dog, or an evil spirit who imprisons her on a cold island). She ends up in a kayak with her exasperated father, in a terrible storm. Sedna's father, believing the gods are angry with Sedna, threw her overboard. She tried to cling to the side of the kayak, but the father chopped off her fingers, and the fingers became the Seals, Whales, Polar Bear, fish, Dolphins and walruses. Sedna sank to the bottom of the sea where she became half fish. She is said to grant bounty to hunters who respect life, and deny it to those who don't. If she isn't properly cared for by her people, she will withhold food and require a shamanistic ritual to get the mud and tangles out of her hair.
6. Sedna has an extremely long and elongated orbit. Typically orbits are circular, leading to speculation that at some point, Sedna had a "close encounter" with another large object which is no longer there, or hasn't been discovered yet. It has been estimated that Sedna would take around 11,400 years to orbit the Sun.
7. Because of the distance, it's not possible to be certain what Sedna is made of, either, or whether it has any surface features. What we do know is that it is Red in colour, almost as red as Mars, and that the colour is relatively homogeneous. The red colour is thought to be caused by a surface coating of hydrocarbon sludge, or tholin, formed from simpler organic compounds after long exposure to ultraviolet radiation. The homogeneous nature of it is probably because, being so far away, Sedna isn't often hit by other objects. We also know that nitrogen, methane, and water ice can be found there.
8. Since Sedna doesn't appear to have a moon, the usual method of calculating size or mass by studying the satellites can't be used. Sedna is the largest object of its type not to have a moon - at least not as far we we know. At first, it was thought it must have a moon because initial calculations suggested it had an unusually long rotational period (20 to 50 days), so there must be a satellite of some kind slowing it down. However, they couldn't find one; and later, further calculations suggested the rotational period is more like 10 hours.
9. Although Sedna is listed on NASA's Solar System exploration website, nothing is going there any time soon. If there was to be a mission it would take over 24 years to get there, using Jupiter's gravity. The most likely launch dates, in order to encounter Sedna at its closest to the sun, and with Jupiter in its best position to assist, would be 6 May 2033 and 23 June 2046.
10. Since Sedna was only discovered in 2003, astrologers don't seem to have agreed exactly what Sedna represents in astrology yet. Most of the sites I looked at were speculating based on what was going on in the world in November 2003. However, a few connections are starting to emerge including on the plus side, forgiveness, discernment, clarity of perception, free will and choice, and on the negative side, abandonment, exile, betrayal, victimisation, abuse, bitterness, fear of commitment and the suppression of the feminine. Sedna rules whaling and products made from sea mammals, deep sea diving, emotional healing, ceremonies taking place in the sea or using talismans connected with the sea, and ceremonial masks.

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