Sedna - new planet discovered in our solar system?

[Orange]

I just read that a possible 10th planet in our solar system has been discovered. It has been named Sedna. Sedna is originally the sea goddess of the Inuit people.

The discovery was done with the Spitzer telescope, and the Hubble telescope has also registered it.

[Orange]

I also read this article a while ago, I'm not sure if the two are related or the same:

A new planet-like object has been found circling the Sun more than one and a half billion kilometres beyond Pluto.


We may discover Kuiper Belt objects bigger than Pluto

Frank Summers
Quaoar, as it has been dubbed, is about 1,280 kilometres across (800 miles) and is the biggest find in the Solar System since Pluto itself 72 years ago.

The object is about one-tenth the diameter of Earth and circles the Sun every 288 years.

It is half Pluto's size, but apparently larger than the ninth planet's moon, Charon.

"It's about the size of all the asteroids put together," Michael Brown of the California Institute of Technology in Pasadena, US, told BBC News Online. "So this thing is really quite big."

Name vote

Brown and colleague Chadwick Trujillo discovered the new world on 4 June.

They used a telescope at the Palomar Observatory in California and followed-up their discovery with the Hubble Space Telescope.


Quaoar lies in the so-called Kuiper Belt

Astronomers named the new object Quaoar, after the creation myth of the Tongva people who inhabited the Los Angeles area before the arrival of the Spanish and other European settlers.

To the indigenous peoples, Quaoar was the great force of nature that summoned all other things into being.

However, Quaoar is not an official name - at least not yet. In a few months, the International Astronomical Union, astronomy's governing body, will vote on it.

For the moment, the object carries the designation 2002 LM60.

Disc of debris

Images of Quaoar had been captured as long ago as 1982, but it was not recognised as a new world. These past observations are being used to pin down its orbit.

"It could easily have been detected 20 years ago, but it wasn't," said Brown.

A good idea of the size of the new world can be gained from the fact that if all the 50,000 numbered asteroids were combined, the resulting body would still be smaller than Quaoar.

Quaoar lies in the so-called Kuiper Belt, a swarm of objects made of ice and rock that orbit the Sun beyond Neptune. They are considered remnants of the swirling disc of debris that coalesced to form the Solar System about five billion years ago.

"This new discovery fits right in with our expectation that there should be a handful of objects as large as Pluto," said astronomer David Jewitt, of the University of Hawaii.

More out there

Jewitt, with then-colleague Jane Luu, discovered the first Kuiper Belt object just a decade ago.

Researchers say that as larger Kuiper Belt objects turn up, the case for regarding Pluto as a fully fledged planet weakens.

Pluto lies within the Kuiper Belt and is considered by many to be merely among the largest of the bunch, and not a planet in its own right.

"It's pretty clear, if we discovered Pluto today, knowing what we know about other objects in the Kuiper Belt, we wouldn't even consider it a planet," said Brown.

Frank Summers, an astrophysicist at the Space Telescope Science Institute in Baltimore, added: "An observation like this just confirms that; that we may discover Kuiper Belt objects bigger than Pluto."

However, there are a great many astronomers who would oppose any notion that Pluto be demoted.

[Orange]

Here is one that is definetly related:

AMERICAN scientists have found a new planet in the solar system, 6.2 billion miles from Earth.

Nasa was expected to reveal details of the discovery - the most distant object ever detected orbiting the sun - later today.

The new planet, the tenth heavenly body in the solar system, has been named Sedna, after the Inuit goddess of the ocean.

The find was made by Dr Michael Brown, associate professor of planetary astronomy at the California Institute of Technology, in Pasadena, midway through a three-year Nasa-funded research project.

And it followed sightings of a "mysterious object" by the Hubble Telescope and the Spitzer Space Telescope.

The new planet, the first to be discovered for more than 70 years, is believed to be about 1250 miles across. But scientists say it may even be larger than the furthest known planet, Pluto, which is 1406 miles across and was the last to be discovered in 1930.

Scientists believe Sedna is 6.2bn miles from Earth in a region of space known as the Kuiper Belt, which contains hundreds of other known bodies. Most are small worlds of rock and ice but some, like Sedna, could be as large as or larger than Pluto.

The importance of Sedna is that it is the first such world discovered in its normal orbit.

Other similar but smaller worlds, like Quaoar and Varuna, originated in the Kuiper Belt but have since been perturbed into different orbits. The discovery will reignite the debate about what is a planet.

One group of astronomers believe that Pluto is not a true planet but merely one of the largest of a vast number of minor objects in the outer solar system.

But some astronomers are already saying the discovery of Sedna re-defines the solar system.

Following Sedna’s discovery, astronomers at the Tenagra Observatory in Arizona were asked to provide positional information so that an orbit could be determined for Sedna.

Most of the planets in the solar system have been known since ancient times.

But Uranus was discovered telescopically from Britain in 1781 by William Herschel. It is too faint to be noticed with the naked eye and its discovery doubled the size of the known solar system overnight.

Herschel received Royal patronage for his sensational discovery and built the biggest and best telescopes in the world, with which he and his son John surveyed the northern and southern skies.

After the discovery of Uranus, astronomers noticed that its orbit was not as it should be in accordance with Newton’s laws and scientists predicted that another more distant planet must be affecting it.

Neptune was first observed in 1846 by Cambridge University mathematician John Couch Adams and Frenchman Urbain Leverrier.

Pluto was discovered in 1930 by a fortunate accident. Calculations which later turned out to be in error had predicted a planet beyond Neptune, based on the motions of Uranus and Neptune.

Not knowing of the error, American scientist Clyde W Tombaugh did a careful sky survey from the Lowell Observatory in Arizona which turned up Pluto anyway.

After the discovery of Pluto, it was quickly determined that Pluto was too small to account for the discrepancies in the orbits of the other planets. The search for Planet X continued but nothing was found. Until now.

[Orange]

OK, after reading through the last article, I could see that the second and third post by me in this thread are indeed about two different objects, with Sedna being quite a bit bigger. Both were discovered recently though.

[Orange]

http://pub.tv2.no/multimedia/na/archive/00140/sedna_ny_planet_fun_140126c.JPG

[Walter BC]

:cool: And there are still so many things to be found out there ...

[sHaHed]

That's interesting...Sedna, the tenth planet in the solar system.

[enola]

Well, since there are still no real definition of what a planet really is, I wouldn't label these new discoveries as "planets".
It's no news that bodies like this would exist in these parts of the solar-system and I don't really see what the fuzz is all about. I find Ceres much more interesting then these Kuiper-belt objects. It may be a little smaller (933km across, which is around 600 miles) but since it's positioned in the Asteroid Belt and thus much much closer to earth.

[Balis-of-Steel]

Astronomers poring over 35 NASA Hubble Space Telescope images of the solar system's farthest known object, unofficially named Sedna, are surprised that the object does not appear to have a companion moon of any substantial size.


At a distance of over 8 billion miles, Sedna is so far away it is reduced to one picture element (pixel) in this image taken in high-resolution mode with Hubble's Advanced Camera for Surveys. Credit: NASA, ESA and M. Brown (Caltech)


This unexpected result might offer new clues to the origin and evolution of objects on the far edge of the solar system.

When Sedna's existence was announced on March 15, its discoverer, Mike Brown of Caltech, was so convinced it had a satellite that an artist's concept of Sedna released to the media included a hypothetical moon.

Brown's prediction was based on the fact that Sedna appears to have a very slow rotation that could best be explained by the gravitational tug of a companion object. Almost all other solitary bodies in the solar system complete a spin in a matter of hours.

"I'm completely baffled at the absence of a moon," says Brown. "This is outside the realm of expectation and makes Sedna even more interesting. But I simply don't know what it means."

Immediately following the announcement of the discovery of Sedna, astronomers turned the Hubble Space Telescope toward the new planetoid to search for the expected companion moon. The space-based platform provides the resolving power needed to make such precision measurements in visible light. "Sedna's image isn't stable enough in ground-based telescopes," says Brown.


Hubble took a total of 35 images of Sedna on March 16, 2004. The planetoid appeared to move slightly between exposures, due to the motion of Hubble around Earth and the motion of the Earth around the Sun. Sedna, too, is moving through space, but too slowly for that to be seen in these images. The fact that the object shows this parallax shift between exposures demonstrates that Sedna is a member of the solar system, and hence is far closer to the Earth than the background star (at right) in the same field of view.

Surprisingly, the Hubble images taken March 16 with the new Advanced Camera for Surveys only show the single object Sedna, along with a faint, very distant background star in the same field of view.

"Despite HST's crisp view (equivalent to trying to see a soccer ball 900 miles away), it still cannot resolve the disk of mysterious Sedna," says Brown. This would place an upper limit in the object's size of being approximately three-quarters the diameter of Pluto, or about 1,000 miles across.

But Brown predicted that a satellite would pop up as a companion "dot" in Hubble's precise view. The object is not there, though there is a very small chance it might have been behind Sedna or transiting in front of it, so that it could not be seen separately from Sedna itself in the Hubble images.

Brown based this prediction on his earlier observations of apparent periodic changes in light reflecting from Sedna's mottled surface. The resulting light curve gives a long rotation period exceeding 20 days (but not greater than 50 days). If true, Sedna would be the slowest rotating object in the solar system after Mercury and Venus, whose slow rotation rates are due to the tidal influence of the Sun.

One easy way out of this dilemma is the possibility that the rotation period is not as slow as the astronomers thought. But even with a careful reanalysis the team remains convinced that the period is correct. Brown admits, "I'm completely lost for an explanation as to why the object rotates so slowly."

Small bodies like asteroids and comets typically complete one rotation in a matter of hours. Pluto's rotation has been slowed to a relatively leisurely six-day period because Pluto is tidally locked to the revolution period of its satellite Charon. Hubble easily resolves Pluto and Charon as two separate bodies. NASA's forthcoming James Webb Space Telescope will provide a platform for further high resolution studies of the infrared light from such distant, cold bodies in our solar system.

The Space Telescope Science Institute (STScI) is operated by the Association of Universities for Research in Astronomy, Inc. (AURA), for NASA, under contract with the Goddard Space Flight Center, Greenbelt, MD. The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency (ESA).