Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Hubble Uncovers Smallest Moons Yet Seen Around Uranus

29.09.2003



Uranus, Rings and Satellites. Hubble Space Telescope


Astronomers have discovered two of the smallest moons yet found around Uranus. The new moons, uncovered by NASA’s Hubble Space Telescope, are about 8 to 10 miles across (12 to 16 km) — about the size of San Francisco.

The two moons are so faint they eluded detection by the Voyager 2 spacecraft, which discovered 10 small satellites when it flew by the gas giant planet in 1986. The newly detected moons are orbiting even closer to the planet than the five major Uranian satellites, which are several hundred miles wide. The two new satellites are the first inner moons of Uranus discovered from an Earth-based telescope in more than 50 years. The International Astronomical Union (IAU) will announce the finding today. The Hubble telescope observations also helped astronomers confirm the discovery of another tiny moon that had originally been spotted in Voyager pictures.

"It’s a testament to how much our Earth-based instruments have improved in 20 plus years that we can now see such faint objects 1.7 billion miles (2.8 billion km) away," says Mark Showalter, a senior research associate at Stanford University in Stanford, Calif., who works at the NASA Ames Research Center, in Moffett Field, Calif. Showalter and Jack Lissauer, a research scientist at the NASA Ames Research Center, used Hubble’s Advanced Camera for Surveys (ACS) to make the discovery. The images were taken Aug. 25, 2003.



The newly discovered moons are temporarily designated as S/2003 U 1 and S/2003 U 2 until the IAU formally approves their discovery. S/2003 U 1 is the larger of the two moons, measuring 10 miles (16 km) across. The Hubble telescope spotted this moon orbiting between the moons Puck, the largest satellite found by Voyager, and Miranda, the innermost of the five largest Uranian satellites. Astronomers previously thought this region was empty space. S/2003 U 1 is 60,600 miles (97,700 km) away from Uranus, whirling around the giant planet in 22 hours and 9 minutes.

The smallest Uranian moon yet found, S/2003 U 2, is 8 miles (12 km) wide. Its orbital path is just 200 to 450 miles (300 to 700 km) from the moon Belinda. S/2003 U 2 is 46,400 miles (74,800 km) away from Uranus and circles the planet in 14 hours and 50 minutes. The tiny moon is part of a densely crowded field of 11 other moons, all discovered from pictures taken by the Voyager spacecraft.

"The inner swarm of 13 satellites is unlike any other system of planetary moons," says co-investigator Jack Lissauer. "The larger moons must be gravitationally perturbing the smaller moons. The region is so crowded that these moons could be gravitationally unstable. So, we are trying to understand how the moons can coexist with each other."

One idea is that some of the moons are young and formed through collisions with wayward comets. For example, the Hubble telescope spotted two small moons orbiting very close to the moon Belinda. One of them is the newly detected moon, S/2003 U 2, which is traveling inside Belinda’s orbit. The other, designated S/1986 U 10, was found in 1999 by astronomer Erich Karkoschka of the University of Arizona, who uncovered the satellite in Voyager pictures. But the finding required confirmation by an Earth-based telescope. This is the first time this moon has been seen since Voyager snapped a picture of it. S/1986 U 10 is 750 miles (1,200 km) away from Belinda.

"Not all of Uranus’s satellites formed over 4 billion years ago when the planet formed," Lissauer says. "The two small moons orbiting close to Belinda, for example, probably were once part of Belinda. They broke off when a comet smashed into Belinda."

The astronomers hope to refine the orbits of the newly discovered moons with further observations. "The orbits will show how the moons interact with one another, perhaps showing how such a crowded system of satellites can be stabilized," Showalter explains. "This could provide further insight into how the moon system formed. Refining their orbits also could reveal whether these moons have any special role in confining or ’shepherding’ Uranus’s 10 narrow rings."

Astronomers stretched the limit of Hubble’s ACS to find the tiny satellites. "These moons are 40 million times fainter than Uranus," Showalter says. "The moons are at 25th magnitude and Uranus is at sixth magnitude. They are blacker than asphalt, if their composition is like the other small, inner moons. So they don’t reflect much light. Even with the sensitivity and high resolution of Hubble’s ACS, we had to overexpose the images of Uranus to pinpoint the moons."

The newly detected moons, when approved by the IAU, will bring the Uranian satellite total to 24. Uranus ranks third in the number of IAU-certified moons behind Jupiter (38) and Saturn (30). Excluding the outer moons that travel in elongated orbits and are probably captured asteroids, Uranus holds the record for the most satellites with 18 in its inner system. All of them have nearly circular orbits. Saturn is second with 17.

Contact:

Donna Weaver
Space Telescope Science Institute, Baltimore, MD
Phone: 410-338-4493; E-mail: dweaver@stsci.edu

Kathleen Burton
NASA Ames Research Center, Moffett Field, CA
Phone: 650-604-1731; E-mail: Kathleen.M.Burton@nasa.gov

Mark Showalter
Stanford University and NASA Ames Research Center
Phone: 650-604-3382; E-mail: Mshowalter@mail.arc.nasa.gov

Jack Lissauer
NASA Ames Research Center
Phone: 650-604-2293; E-mail: jlissauer@ringside.arc.nasa.gov

M. Showalter | Hubble Site
Further information:
http://hubblesite.org
http://www.nasa.gov

More articles from Physics and Astronomy:

nachricht Unconventional superconductor may be used to create quantum computers of the future
19.02.2018 | Chalmers University of Technology

nachricht Hubble sees Neptune's mysterious shrinking storm
16.02.2018 | NASA/Goddard Space Flight Center

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: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

Im Focus: Hybrid optics bring color imaging using ultrathin metalenses into focus

For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.

But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...

Im Focus: Stem cell divisions in the adult brain seen for the first time

Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.

The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...

Im Focus: Interference as a new method for cooling quantum devices

Theoretical physicists propose to use negative interference to control heat flow in quantum devices. Study published in Physical Review Letters

Quantum computer parts are sensitive and need to be cooled to very low temperatures. Their tiny size makes them particularly susceptible to a temperature...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

Contacting the molecular world through graphene nanoribbons

19.02.2018 | Materials Sciences

When Proteins Shake Hands

19.02.2018 | Materials Sciences

Cells communicate in a dynamic code

19.02.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>