They were discovered in 1977 by James L.
Its low orbit, with an orbital period that is shorter than a Martian day, is decaying due to tidal deceleration. === Jupiter === Jupiter's ring system was the third to be discovered, when it was first observed by the Voyager 1 probe in 1979, and was observed more thoroughly by the Galileo orbiter in the 1990s.
Nauka, Moscow, 1988 (in Russian). Celestial mechanics Articles containing video clips
Hints of the rings were seen for decades prior to their conclusive discovery by Voyager 2 in 1989. ==Rings systems of minor planets and moons== Reports in March 2008 suggested that Saturn's moon Rhea may have its own tenuous ring system, which would make it the only moon known to have a ring system.
Its low orbit, with an orbital period that is shorter than a Martian day, is decaying due to tidal deceleration. === Jupiter === Jupiter's ring system was the third to be discovered, when it was first observed by the Voyager 1 probe in 1979, and was observed more thoroughly by the Galileo orbiter in the 1990s.
In the time between then and 2005, observations by Voyager 2 and the Hubble Space Telescope led to a total of 13 distinct rings being identified, most of which are opaque and only a few kilometers wide.
Larger rocks and boulders may also be present, and in 2007 tidal effects from eight 'moonlets' only a few hundred meters across were detected within Saturn's rings.
Similarly, Proxima Centauri c has been observed to be far brighter than expected for its low mass of 7 Earth masses, which may be attributed to a ring system of about 5 . A sequence of occultations of the star 1SWASP J140747.93-394542.6 observed in 2007 over 56 days was interpreted as a transit of a ring system of a (not directly observed) substellar companion dubbed "J1407b".
Hints of the rings were seen for decades prior to their conclusive discovery by Voyager 2 in 1989. ==Rings systems of minor planets and moons== Reports in March 2008 suggested that Saturn's moon Rhea may have its own tenuous ring system, which would make it the only moon known to have a ring system.
As of 2020, one candidate extrasolar ring system has been found by this method, around HIP 41378 f. Fomalhaut b was found to be large and unclearly defined when detected in 2008.
A later study published in 2010 revealed that imaging of Rhea by the Cassini spacecraft was inconsistent with the predicted properties of the rings, suggesting that some other mechanism is responsible for the magnetic effects that had led to the ring hypothesis. It had been theorized by some astronomers that Pluto might have a ring system.
The rings were discovered when astronomers observed Chariklo passing in front of the star UCAC4 248-108672 on June 3, 2013 from seven locations in South America.
This formation mechanism predicts that roughly 10% of centaurs will have experienced potentially ring-forming encounters with giant planets. ===Haumea=== A ring around Haumea, a dwarf planet and resonant Kuiper belt member, was revealed by a stellar occultation observed on 21 January 2017.
As of 2020, one candidate extrasolar ring system has been found by this method, around HIP 41378 f. Fomalhaut b was found to be large and unclearly defined when detected in 2008.
This was hypothesized to either be due to a cloud of dust attracted from the dust disc of the star, or a possible ring system, though in 2020 Fomalhaut b itself was determined to very likely be an expanding debris cloud from a collision of asteroids rather than a planet.
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