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Saturn Compass Image
Composite Image of Saturn with Six Moons
This composite image, taken by NASA’s Hubble Space Telescope on June 6, 2018, shows the ringed planet Saturn with six of its 62 known moons. From left to right, the moons visible in this image are Dione, Enceladus, Tethys, Janus, Epimetheus, and Mimas. With a diameter of 698 miles, Dione is the fourth-largest moon of Saturn and the largest of the siblings in this family portrait. The smallest satellite in this picture is the irregularly shaped Epimetheus, with a size of 89 miles by 67 miles by 61 miles.
The moons seen here are icy and cratered. Enceladus is considered a candidate for primitive life because it is outgassing water vapor from a subsurface ocean. Based on data from the NASA Cassini mission to Saturn, scientists hypothesize that a small, wayward moon like one of these disintegrated 200 million years ago to form Saturn’s ring system. The image is a composite because the moons move during the Saturn exposures, and individual frames must be realigned to make a color portrait.
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 Saturn's orbit about the sun is 9.5 astronomical units (A.U.) or roughly 1.4 billion km.
- DimensionsDimensionsThe physical size of the object or the apparent angle it subtends on the sky.The planet (without rings) has a diameter of roughly 75,000 miles (120,000 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.The HST observations include those from the Outer Planet Atmospheres Legacy (OPAL) Program 15262 (A. Simon) - InstrumentInstrumentThe science instrument used to produce the data.WFC3/UVIS
- Exposure DatesExposure DatesThe date(s) that the telescope made its observations and the total exposure time.June 6, 2018
- FiltersFiltersThe camera filters that were used in the science observations.F395N, F502N, F631N
- Object NameObject NameA name or catalog number that astronomers use to identify an astronomical object.Saturn
- Object DescriptionObject DescriptionThe type of astronomical object.Saturn and moons near opposition
- Release DateJuly 26, 2018
- Science ReleaseSaturn and Mars Team Up to Make Their Closest Approaches to Earth in 2018
- Credits
These images are a composite of separate exposures acquired by the WFC3 instrument on the Hubble Space Telescope. Several filters were used to sample narrow wavelength ranges. The color results from assigning different hues (colors) to each monochromatic (grayscale) image associated with an individual filter. In this case, the assigned colors are: Blue: F395N Green: F502N Red: F631N
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Claire Andreoli
NASA’s Goddard Space Flight Center
Greenbelt, Maryland
claire.andreoli@nasa.gov
