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Newly Discovered Moon and Rings of Uranus

These composite images from several observations by NASA's Hubble Space Telescope reveal a pair of newly discovered rings encircling the planet Uranus. The left composite image is made from Hubble data taken in 2003. The new dusty rings are extremely faint and required long exposures to capture their image. The background speckle pattern is noise in the image. The outermost ring (R/2003 U 1) is likely replenished by dust blasted off a newly discovered satellite called Mab, embedded in the ring and visible as a bright streak at the top of the outer ring. The new outermost ring is twice the radius of the previously known ring system around Uranus, as seen near image center. (The inner rings are much brighter, so no noise is visible in the background). Approximately halfway between the outermost ring and inner ring system is a second newly discovered ring (R/2003 U2). Only a faint segment of it appears at the 12:00 o'clock position. Because of the long exposures, the moons are smeared out and appear as arcs within the ring system.
In the image at right, taken two years later, the rings appear more oblique because Uranus has moved along its solar orbit. The planet Uranus itself is approaching spring equinox, when the Sun will be directly shining over the planet's equator in 2007. Cloud bands and storms are becoming more pronounced in the atmosphere. A bright storm appears at northern latitudes in the 2005 images. The images were taken with the Advanced Camera for Surveys, using a clear filter.
About the Object
- DistanceDistanceThe physical distance from Earth to the astronomical object. Distances within our solar system are usually measured in Astronomical Units (AU). Distances between stars are usually measured in light-years. Interstellar distances can also be measured in parsecs.The semi-major axis of Uranus's orbit about the sun is 19.18 Astronomical Units (A.U.) or roughly 2.9 billion km.
- DimensionsDimensionsThe physical size of the object or the apparent angle it subtends on the sky.Uranus (without rings) has a diameter of roughly 32,000 miles (51,000 km) at the equator.
About the Data
- Data DescriptionData DescriptionProposal: A description of the observations, their scientific justification, and the links to the data available in the science archive.
Science Team: The astronomers who planned the observations and analyzed the data. "PI" refers to the Principal Investigator.10473 : M. Sh owalter (SETI Institute) and J. Lissauer (NASA Ames Research Center)
- InstrumentInstrumentThe science instrument used to produce the data.HST>ACS/HRC
- Exposure DatesExposure DatesThe date(s) that the telescope made its observations and the total exposure time.2003 (left), and August 2005, Exposure Time: 3.7 hours (right)
- FiltersFiltersThe camera filters that were used in the science observations.Clear, F330W (U), F475W (g), F606W (V), F814W (I)
- Object NameObject NameA name or catalog number that astronomers use to identify an astronomical object.Uranus
- Object DescriptionObject DescriptionThe type of astronomical object.Planet
- Release DateDecember 22, 2005
- Science ReleaseNASA’s Hubble Discovers New Rings and Moons Around Uranus
- Credit
Related Images & Videos

Newly Discovered Moons and Rings of Uranus (Annotated)
These composite images from several observations by NASA's Hubble Space Telescope reveal a pair of newly discovered rings encircling the planet Uranus. The left composite image is made from Hubble images taken in 2003. The new dusty rings are extremely faint and required long...
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Claire Andreoli
NASA’s Goddard Space Flight Center
Greenbelt, Maryland
claire.andreoli@nasa.gov