tenth planet?

[The Last Conformist]

"Alpha Centauri" is systematic name, denoting the brightest (as seen from the Earth) star in the constellation Centaurus. Similarly, Beta Lyrae is the second brightest star in Lyra (the brightest one, Alpha Lyrae, is more commonly known as Vega).

In principle, any star within the constellation Centaurus is "something Centauri", but impractice these names are only used for relatively bright and near stars (which not to say they're necessarily bright enough to be visible).

No planets are known in the Alpha Centauri system. It's, BTW, a triple, consistint of Alpha Centauri A, Alpha Centauri B (two roughly sun-like stars with medium separation - SMAC supposedly takes place on a planet orbiting A), and Alpha Centauri C (a red dwarf star orbiting the other two in a very wide orbit). C is commonly known as Proxima Centauri, because it is the star currently closest to the Sun.

 

[the mormegil]

Astronomers have thought for a while that there was another planet past Pluto, because there was something pulling on Pluto's orbit which they couldn't see. I guess this is probably it.

 

[The Last Conformist]

It most certainly isn't, and that theory is long since abandoned - the apparent orbital irregularities turned out to be simply errors of measurement.

Edit: And the reason it certainly isn't is simply that it's way to small and far away to have any noticeable impact on Pluto's orbit.

 

[the mormegil]

Originally posted by The Last Conformist
It most certainly isn't, and that theory is long since abandoned - the apparent orbital irregularities turned out to be simply errors of measurement.

Edit: And the reason it certainly isn't is simply that it's way to small and far away to have any noticeable impact on Pluto's orbit.

Well the scientific community could have told me! Puh, they can't do anything right...

 

[the mormegil]

EDIT: Sorry, double post

 

[Bozo Erectus]

Its from the Oort Cloud

The elliptical orbit of Sedna is unlike anything previously seen by astronomers. However, it resembles that of objects predicted to lie in the hypothetical Oort cloud. The cloud is thought to explain the existence of certain comets. It is believed to surround the Sun and extend outward halfway to the star closest to the Sun. But Sedna is 10 times closer than the predicted distance of the Oort cloud. Brown said this "inner Oort cloud" may have been formed by gravity from a rogue star near the Sun in the solar system's early days.

"The star would have been close enough to be brighter than the full moon, and it would have been visible in the daytime sky for 20,000 years," Brown explained. Worse, it would have dislodged comets farther out in the Oort cloud, leading to an intense comet shower that could have wiped out some or all forms of life that existed on Earth at the time.

Rabinowitz said there is indirect evidence that Sedna may have a moon. The researchers hope to check this possibility with NASA's Hubble Space Telescope. Trujillo has begun to examine the object's surface with one of the world's largest optical/infrared telescopes, the 8-meter (26-foot) Frederick C. Gillett Gemini Telescope on Mauna Kea, Hawaii. "We still don't understand what is on the surface of this body. It is nothing like what we would have predicted or what we can explain," he said.

Sedna will become closer and brighter over the next 72 years, before it begins its 10,500-year trip to the far reaches of the solar system. "The last time Sedna was this close to the Sun, Earth was just coming out of the last ice age. The next time it comes back, the world might again be a completely different place," Brown said.

http://www.jpl.nasa.gov/releases/2004/85.cfm

 

[The Last Conformist]

The existence of an Inner Oort Cloud had actually been suggested well before the slew of trans-Neptunian discoveries of recent years - it's thought to act as a "reservoir" of medium-time comets.

What would be truly spectacular were if something the size of Sedna was sent inwards on a cometary orbit ...