difference between Sedna, Eris, and Planet X. one of which is considered Nibiru?

I had problems with finding which is which. Different pages have different information and different names. Does anyone know the difference between Sedna, Eris, and Planet X. which is the largest and those are the same. What did the ancient people believed that Nibiru?

Sedna and Eris are dwarf planets (Eris is the largest of the two, larger than Pluto) orbit the Sun beyond Neptune. Both are too young to have been seen by ancient astronomers. "Planet X" is a generic name given to any hypothetical planet. Nibiru was originally the Sumerian name of a bright object in the sky, maybe Jupiter, maybe something else. Now, however … … Fictitious system is a member of the Sun, presumably five times the size of Earth and must pass close enough to cause catastrophic damage on 21.12.2012. We know it's fiction, for several reasons: 1. An object five times the size of Earth would be visible in telescopes decades before the court came to the coast. No object has been, despite decades of observation by millions of amateur and professional astronomers. 2. Such an object would also have a significant effect of gravity on nearby objects, like the rest of the planets affairs, and refused to follow its planned orbit. In fact, the planet Neptune was discovered in the errors in the orbits of the planets known predicted. Because planets are where they are supposed to be calculated is not large invisible object in the drawing of his way. 3. Nibiru advertisers change their forecasts every time a false prediction is age. Nibiru was originally scheduled to appear in 2003, now is supposed to be in 2012, so who knows what they're going to give 2013? Do you remember the predictions of the end Y2K world? 2012 doomsday predictions are so accurate. The people behind the hysteria of 2012 are there for the money. They sell many books and videos to people they do not know better. Many of them said the same in 2003 and 2012 Earth survived when elected by the importance which is the Mayan calendar. When it is 2012 and we are still here, simply choose another time and sell more books and videos.

Nibiru – NASA – SOHO – A reply to dumb people!!!