Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Good News For Pluto - Astronomers Say KBOs May Be Smaller Than Thought


Pluto’s status as our solar system’s ninth planet may be safe if a recently discovered Kuiper Belt Object is a typical "KBO" and not just an oddball.

Astronomers have new evidence that KBOs (Kuiper Belt Objects) are smaller than previously thought.

KBOs - icy cousins to asteroids and the source of some comets - are the leftover building blocks of the outer planets. Astronomers using the world’s most powerful telescopes have discovered about 1,000 of these objects orbiting beyond Neptune since discovering the first one in 1992. These discoveries fueled debate on whether Pluto is a planet or a large (1,400-mile diameter) closer-in KBO.

Researchers estimate that the total mass of the Kuiper Belt is about a tenth of Earth’s mass. Most theorize that there are more than 10,000 KBOs with diameters greater than 100 kilometers (62 miles), compared to 200 asteroids known to be that large in the main asteroid belt between Mars and Jupiter. "People were finding all these KBOs that were huge - literally half the size of Pluto or larger," University of Arizona astronomer John Stansberry said. "But those supposed sizes were based on assumptions that KBOs have very low albedos, similar to comets."

Albedo is a measure of how much light an object reflects. The more light an object reflects, the higher its albedo. Actual data on Kuiper Belt Object albedos have been hard to come by because the objects are so distant, dim and cold. Many astronomers have assumed that KBO albedos - like comet albedos - are around four percent and have used that number to calculate KBO diameters.

However, in early results from their Spitzer Space Telescope survey of 30 Kuiper Belt Objects, Stansberry and colleagues found that a distant KBO designated 2002 AW197 reflects 18 percent of its incident light and is about 700 kilometers (435 miles) in diameter. That’s considerably smaller and more reflective than expected, Stansberry said.

"2002 AW197 is believed to be one of the largest KBOs thus far discovered," he said. "These results indicate that this object is larger than all but one main-belt asteroid (Ceres), about half the size of Pluto’s moon, Charon, and about 30 percent as large and a tenth as massive as Pluto."

Stansberry and his colleagues took the data with Spitzer’s Multiband Imaging Photometer (MIPS) on April 13, 2004. George Rieke’s team at the University of Arizona developed and built the extremely heat-sensitive MIPS. It detects heat from very cold objects by taking images at far-infrared wavelengths.

In this case, MIPS detected heat from a Kuiper Belt Object with a surface temperature of around minus 370 degrees Fahrenheit at an astonishing distance of 4.4 billion miles (7 billion kilometers), or one-and-a-half times farther away frm the sun than Pluto.

Without MIPS, astronomers operating under the assumption that 2002 AW197 reflects four percent of its incident light would calculate that it is 1500 kilometers (932 miles) in diameter, or two-thirds as large as Pluto, Stansberry said. "We’re finally starting to get data on the basic physical parameters of KBOs," Stansberry said. "That will help us determine what their compositions are, how they evolve, how massive they are, what their real size distributions and dynamics are and how Pluto fits into the whole picture," he said.

Such data will also offer insight on how comets are processed on their successive journeys around the sun, he added. "It’s not surprising that comets are darker than KBOs," Stansberry said."When something in the Kuiper Belt chips off a piece of a Kuiper Belt Object, presumably that piece would have a higher albedo on its first swing through the inner solar system. But it doesn’t take long before it loses its high albedo surface and builds up a lot of very dark materials, at least in its outermost surface."

Others with Stansberry in this Spitzer study are Dale Cruikshank and Josh Emery of NASA Ames Research Center, Yan Fernandez of the University of Hawaii, George Rieke of the University of Arizona and Michael Werner of NASA’s Jet Propulsion Laboratory. Stansberry said the team will finish collecting their KBO data with Spitzer soon. "We’ll know a lot more about how big and bright these things are by this time next year," he said.

Stansberry is presenting the research today at the 86th annual meeting of the American Astronomical Society Division of Planetary Science in Louisville, Ky. More information about this and other new results from the Spitzer Space Telescope is on the Web at The Spitzer Space Telescope is managed for NASA by the Jet Propulsion Laboratory in Pasadena, Calif.

Lori Stiles | UA News Services
Further information:

More articles from Physics and Astronomy:

nachricht OU-led team discovers rare, newborn tri-star system using ALMA
27.10.2016 | University of Oklahoma

nachricht First results of NSTX-U research operations
26.10.2016 | DOE/Princeton Plasma Physics Laboratory

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Etching Microstructures with Lasers

Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.

This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...

Im Focus: Light-driven atomic rotations excite magnetic waves

Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion

Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

How nanoscience will improve our health and lives in the coming years

27.10.2016 | Materials Sciences

OU-led team discovers rare, newborn tri-star system using ALMA

27.10.2016 | Physics and Astronomy

'Neighbor maps' reveal the genome's 3-D shape

27.10.2016 | Life Sciences

More VideoLinks >>>