Featured Research

from universities, journals, and other organizations

Hubble Finds 'Tenth Planet' Is Slightly Larger Than Pluto

Date:
April 17, 2006
Source:
Space Telescope Science Institute
Summary:
NASA's Hubble Space Telescope has resolved the "tenth planet," nicknamed "Xena," for the first time and has found that it is only just a little larger than Pluto. Though previous ground-based observations suggested that Xena was about 30 percent greater in diameter than Pluto, Hubble observations taken on Dec. 9 and 10, 2005, yield a diameter of 1,490 miles (with an uncertainty of 60 miles) for Xena. Pluto's diameter, as measured by Hubble, is 1,422 miles.

NASA's Hubble Space Telescope has resolved the "tenth planet," nicknamed "Xena," for the first time and has found that it is only just a little larger than Pluto.
Credit: NASA, ESA, and M. Brown (California Institute of Technology)

NASA's Hubble Space Telescope has resolved the "tenth planet," nicknamed "Xena" for the first time, and has found that it is only just a little larger than Pluto.

Though previous ground-based observations suggested that Xena was about 30 percent greater in diameter than Pluto, Hubble observations taken on Dec. 9 and 10, 2005, yield a diameter of 1,490 miles (with an uncertainty of 60 miles) for Xena. Pluto's diameter, as measured by Hubble, is 1,422 miles.

"Hubble is the only telescope capable of getting a clean visible-light measurement of the actual diameter of Xena," said Mike Brown, planetary scientist at the California Institute of Technology in Pasadena, Calif. Brown's research team discovered Xena, and their results have been accepted for publication in the Astrophysical Journal.

It only required a couple of Hubble images to nail Xena's diameter. Located 10 billion miles away, but with a diameter that is a little more than half the width of the United States, the object is 1.5 pixels across in Hubble's view. That's enough to precisely make a size measurement.

Because Xena is smaller than earlier thought, but comparatively bright, it must be one of the most reflective objects in the solar system. The only object more reflective is Enceladus, a geologically active moon of Saturn whose surface is continuously recoated with highly reflective ice by active geysers.

Xena's bright reflectivity is possibly due to fresh methane frost overlying the surface. It is possible that Xena had an atmosphere when it was closer to the Sun, but "froze out" at its current large distance, and material settled on its surface as frost.

Another possibility is that Xena is also continuously leaking methane gas from its warmer interior. When this methane makes it to the cold surface it immediately freezes solid, covering craters and other features to make this Kuiper Belt object (KBO) uniformly bright to Hubble's telescopic eye.

Xena is officially catalogued as 2003 UB313. Its orbital period is about 560 years, and the KBO is now very close to aphelion (the point on its orbit that is farthest from the Sun).

Brown next plans to use Hubble and other telescopes to study other recently discovered KBOs that are almost as large as Pluto and Xena. The Kuiper Belt is a vast ring of primordial icy comets and larger bodies encircling Neptune's orbit.

Finding that the largest known KBO is a virtual twin to Pluto may only further complicate the debate about whether to categorize the large icy worlds that dwell in the Kuiper Belt as planets. If Pluto were considered to be the minimum size for a planet, then Xena would fulfill this criterion, too.


Story Source:

The above story is based on materials provided by Space Telescope Science Institute. Note: Materials may be edited for content and length.


Cite This Page:

Space Telescope Science Institute. "Hubble Finds 'Tenth Planet' Is Slightly Larger Than Pluto." ScienceDaily. ScienceDaily, 17 April 2006. <www.sciencedaily.com/releases/2006/04/060417131556.htm>.
Space Telescope Science Institute. (2006, April 17). Hubble Finds 'Tenth Planet' Is Slightly Larger Than Pluto. ScienceDaily. Retrieved September 1, 2014 from www.sciencedaily.com/releases/2006/04/060417131556.htm
Space Telescope Science Institute. "Hubble Finds 'Tenth Planet' Is Slightly Larger Than Pluto." ScienceDaily. www.sciencedaily.com/releases/2006/04/060417131556.htm (accessed September 1, 2014).

Share This




More Space & Time News

Monday, September 1, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Space Shuttle Discovery's Legacy, 30 Years Later

Space Shuttle Discovery's Legacy, 30 Years Later

Newsy (Aug. 30, 2014) The space shuttle Discovery launched for the very first time 30 years ago. Here's a look back at its legacy. Video provided by Newsy
Powered by NewsLook.com
Experiment Tests Whether Universe Is Actually A Hologram

Experiment Tests Whether Universe Is Actually A Hologram

Newsy (Aug. 27, 2014) Researchers at Fermilab are using a device called "The Holometer" to test whether our universe is actually a 2-D hologram that just seems 3-D. Video provided by Newsy
Powered by NewsLook.com
SpaceX’s Falcon 9 Rocket Explodes After Liftoff

SpaceX’s Falcon 9 Rocket Explodes After Liftoff

Newsy (Aug. 23, 2014) The private spaceflight company says it is preparing a thorough investigation into Friday's mishap. Video provided by Newsy
Powered by NewsLook.com
Did Russia Really Find Plankton On The ISS? NASA Not So Sure

Did Russia Really Find Plankton On The ISS? NASA Not So Sure

Newsy (Aug. 21, 2014) Russian cosmonauts say they've found evidence of sea plankton on the International Space Station's windows. NASA is a little more skeptical. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins