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Saturn Opposition 2018
Hubble Takes Portrait of Opulent Ring World
Saturn is by far the solar system’s most photogenic planet, and in this latest Hubble Space Telescope snapshot it is especially so because Saturn’s magnificent ring system is near its maximum tilt toward Earth (which was in 2017).
Hubble was used to observe the planet on June 6, 2018, when Saturn was only approximately 1.36 billion miles from Earth, nearly as close to us as it ever gets.
Saturn was photographed as it approached a June 27 opposition, when the planet is directly opposite to the Sun in the night sky and is at its yearly closest distance to the Earth. Though all of the gas giants boast rings, Saturn’s are the largest and most spectacular, stretching out eight times the radius of the planet.
Saturn’s stunning rings were first identified as a continuous disk around the planet by Dutch astronomer Christiaan Huygens in 1655. 325 years later, NASA’s Voyager 1 spacecraft flyby of Saturn resolved thousands of thin, fine ringlets. Data from NASA’s Cassini mission suggests the rings formed 200 million years ago, roughly around the time of the dinosaurs and Earth’s Jurassic period. The gravitational disintegration of one of Saturn’s small moons created myriad icy debris particles, and collisions today likely continually replenish the rings.
Visible in this Hubble image are the classic rings as recorded by early skywatchers. From the outside in are the A ring with the Encke Gap, the Cassini Division, the B ring, and the C ring with the Maxwell Gap.
Saturn’s appearance changes due to its seasons, caused by the planet’s 27-degree axial tilt. It is now summer in Saturn’s northern hemisphere and the atmosphere is more active. This may be responsible for a string of bright clouds visible near the northern polar region that are the remnants of a disintegrating storm. Small, mid-latitude puffs of clouds are also visible. Hubble’s view also resolves a hexagonal pattern around the north pole, a stable and persistent wind feature discovered during the Voyager flyby in 1981.
Saturn’s colors come from hydrocarbon hazes above the ammonia crystals in the upper cloud layers. Unseen lower-level clouds are either ammonium hydrosulfide or water. The planet’s banded structure is caused by the winds and the clouds at different altitudes.
This is the first image of Saturn taken as part of the Outer Planet Atmospheres Legacy (OPAL) project. OPAL is helping scientists understand the atmospheric dynamics and evolution of our solar system’s gas giant planets.
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 observed 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
