An artist's view of Sedna (2003VB12)

In March, 2004 astronomers announced the discovery of  the coldest, most distant object known to orbit the Sun. The object was found at a distance 90 times greater than that from the Sun to the Earth -- about 3 times further than Pluto.  Astronomers have given it the name of Sedna (2003VB12).

Is Sedna a planet? No, it will likely be classified as a dwarf planet along with Eris and Pluto.

The discovery was made using the Palomar Observatory's 48-inch Samuel Oschin Telescope on 14 November 2003 by the team of Mike Brown (Caltech), Chad Trujillo (Gemini Observatory) and David Rabinowitz (Yale).

The discovery was made as a part of ongoing survey of the outer solar system using the Palomar QUEST camera and the Samuel Oschin Telescope at the Palomar Observatory. This survey has been operating since the fall of 2001, with the switch to the QUEST camera happening in the summer of 2003. To date the survey has turned up around 40 bright Kuiper belt objects.

 To find objects, they take three pictures of a small region of the night sky over three hours and look for something that moves. The many billions of stars and galaxies visible in the sky appear stationary, while satellites, planets, asteroids, and comets appear to move. Objects in the inner Oort cloud are extremely distant and so move extremely slowly. The process is descibed in more detail on this page.

Below is an animated gif that shows the three discovery images. The total area of sky shown in the bottom image is equivalent in size to the head of a pin held at arm's length. Incidentally, that is how big the Sun would appear from Sedna.  

For more information and images visit Mike Brown's Sedna Webpage.

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