Astro Blog

By Katherine Kornei , Eos/AGU. Excerpt: Using data from the Cassini spacecraft, researchers studying one of the rings recently uncovered gaps just a few tens of meters wide that they believe surround unseen mini moonlets. ...In addition to capturing  more than 450,000 images  of the Saturnian system, the spacecraft inadvertently tracked distant stars poking through Saturn’s rings. ...The researchers spotted dozens of places in Saturn’s C ring— one of its innermost rings —that appeared to be 100% transparent. ...Their elongated geometry was a tip-off to their potential identity—similarly shaped structures, albeit much larger, have been  spotted in the outer regions of Saturn’s A ring . Known as propellers [resembling airplane propellers], those features are big enough to show up in Cassini imagery rather than just occultation data, Jerousek said. ...Scientists believe that propellers exist because of unseen moonlets measuring, at most, several hundred meters in diameter....  Full articl

https://eos.org/articles/saturns-shiny-rings-may-be-pretty-young By  Kimberly M. S. Cartier , Eos/AGU.  Excerpt: ...Data from NASA’s Cassini mission showed how fast dust has been pelting the Saturnian system, revealing that for the rings to have remained as shiny and dust-free as they are, they can be only as much as 400 million years old, much younger than the planet itself. ...The Sun and its planets formed around 4.5 billion years ago, and many of the planets’ moons, including ours, followed not long after. Astronomers initially thought that  Saturn’s rings  formed during that early dynamical period, when large collisions were common. ...The rings’ orbits and compositions support the idea they are old. ...Measurements of the rainfall rate and the total mass of the rings from NASA’s  Cassini spacecraft , which orbited Saturn for 13 years, suggested that the rings must be far younger than the planet; otherwise, they would have disappeared already. Cassini also revealed that the rings

https://www.nytimes.com/2023/02/08/science/quaoar-rings-roche-limit.html By Kenneth Chang , The New York Times.  Excerpt: Quaoar, which orbits the sun in the distant Kuiper belt, is the latest small object shown to have a ring like the ones around Saturn. ...Quaoar (pronounced KWA-wahr ...is a little less than half the diameter of Pluto and about a third of the diameter of Earth’s moon. It is likely to be big enough to  qualify as a dwarf planet , pulled by its gravity into a round shape. ...The ring is not visible in telescope images. Rather, astronomers found it indirectly, when distant stars happened to pass behind Quaoar, blocking the starlight. From 2018 through 2021, Quaoar passed in front of four stars, and astronomers on Earth were able to observe the shadow of the eclipses, also known as stellar occultations. However, they also observed some dimming of the starlight before and after the star blinked out. That pointed to a ring obscuring part of the light, an international team

https://www.scientificamerican.com/article/the-best-of-jwsts-cosmic-portraits/ By Clara Moskowitz , Scientific American.  Excerpt: [Images Jupiter, Neptune and their rings as well as the phantom galaxy, M74.]

https://www.nasa.gov/feature/goddard/2022/new-webb-image-captures-clearest-view-of-neptune-s-rings-in-decades By NASA  Laura Betz   (Goddard Space Flight Center, Greenbelt, MD), Hannah Braun and Christine Pulliam (Space Telescope Science Institute, Baltimore, MD).  Excerpt: ...Webb’s extremely stable and precise image quality permits these very faint rings to be detected so close to Neptune. ...Compared to the gas giants, Jupiter and Saturn, Neptune is much richer in elements heavier than hydrogen and helium. This is readily apparent in Neptune’s signature blue appearance in  Hubble Space Telescope images  at visible wavelengths, caused by small amounts of gaseous methane. Webb’s  Near-Infrared Camera  (NIRCam) images objects in the near-infrared range from 0.6 to 5 microns, so Neptune does not appear blue to Webb. In fact, the methane gas so strongly absorbs red and infrared light that the planet is quite dark at these near-infrared wavelengths, except where high-altitude clouds are p

https://www.nytimes.com/2019/01/25/science/saturn-day-length.html Source:   By Nadia Drake, The New York Times. Excerpt: For decades, it was a nagging mystery — how long does a day last on Saturn? Earth pirouettes around its axis once every 24 hours or so, while Jupiter spins comparatively briskly, once in roughly 9.8 Earth-hours. And then there is Venus, a perplexingly sluggish spinner that takes 243 Earth-days to complete a full rotation. With Saturn, it turns out the answer rippled in plain view, in the planet’s lustrous rings. After reading small, spiraling waves in those bands, sculpted by oscillations from Saturn’s gravity, scientists reported this month in the Astrophysical Journal that one Saturnian day is a mere 10 hours, 33 minutes and 38 seconds long, measured in Earth time. ...Saturn has been stubbornly secretive about its days. Its buttery clouds don’t bear helpful markings that scientists might use to track the planet’s rotation, and they can't easily use its near

https://www.scientificamerican.com/article/cassinis-ldquo-grand-finale-rdquo-will-be-a-blaze-of-glory/ Source:   By Lee Billings, Scientific American For Investigation:  6.1, 8.2 Excerpt: The Cassini orbiter will burn out, but its legacy won’t fade away. ...For NASA’s Cassini orbiter—its fuel dwindling after 13 years exploring Saturn, along with the planet’s sprawling rings and dozens of icy moons—the end will come Friday at 7:55 A.M. Eastern time. That’s when mission planners project radio communications will be lost with the two-ton, bus-size spacecraft as it plunges into the giant planet’s turbulent atmosphere at more than 122,000 kilometers per hour. ...“We are concluding the longest, deepest, most comprehensive scientific exploration of a remote planetary system ever undertaken, a system so alien it might as well have been orbiting another star in another galaxy,” says Carolyn Porco, the planetary scientist who leads Cassini’s imaging team. “And we have been profoundly succe

Source:   By JoAnna Wendel, Earth & Space Science News, EoS (AGU) Excerpt: It’s a flying saucer! No, a celestial empanada! Or space ravioli? Nope—the weird raw images dropped by NASA’s Jet Propulsion Laboratory this week feature Saturn’s tiny moon Pan and its equatorial fringe in unprecedented detail. The Cassini spacecraft, which has been orbiting Saturn since 2004, will crash into Saturn later this year. But its final descent brings the spacecraft closer than ever before to Saturn’s rings and offers scientists a wealth of new research opportunities.This is because the spacecraft has entered its “ring grazing orbits,” Carolyn Porco, leader of the imaging science team for Cassini and current visiting scholar at the University of California in Berkeley, told Eos. ...This close orbit allows the spacecraft to take close-up pictures of moons like Pan, which orbits Saturn at a distance of 134,000 kilometers. The new images of the 35-kilometer-wide moon feature a resolut

Source:   By Robert Sanders, UC Berkeley News. For GSS A Changing Cosmos chapter 7. Excerpt: Mars’ largest moon, Phobos, is slowly falling toward the planet, but rather than smash into the surface, it likely will be shredded and the pieces strewn about the planet in a ring like the rings encircling Saturn, Jupiter, Uranus and Neptune  ...in 10-20 million years... that will persist for anywhere from one million to 100 million years, according to two young earth scientists at the University of California, Berkeley. In a paper appearing online this week in Nature Geoscience, UC Berkeley postdoctoral fellow Benjamin Black and graduate student Tushar Mittal estimate the cohesiveness of Phobos and conclude that it is insufficient to resist the tidal forces that will pull it apart when it gets closer to Mars. Just as earth’s moon pulls on our planet in different directions, raising tides in the oceans, for example, so too Mars tugs differently on different parts of Phobos. As

Source:   NASA RELEASE 13-120 Excerpt: ...NASA's Cassini spacecraft has provided the first direct evidence of small meteoroids breaking into streams of rubble and crashing into Saturn's rings. These observations make Saturn's rings the only location besides Earth, the moon, and Jupiter where scientists and amateur astronomers have been able to observe impacts as they occur.  ... Saturn's rings act as very effective detectors of many kinds of surrounding phenomena, including the interior structure of the planet and the orbits of its moons.  ... http://www.nasa.gov/cassini  http:// www.nasa.gov/home/hqnews/2013/apr/HQ_13-120_Saturn_Meteors.html

Source:   NASA Excerpt: …A new scientific model suggests Saturn's rings formed from the shredding of an ancient moon's outer envelope before it finally collided with Saturn.  solarsystem.nasa.gov/yss/display.cfm

Source:    M. R. Showalter, Science  Excerpt: Jupiter’s main ring shows vertical corrugations reminiscent of those recently detected in the rings of Saturn. The Galileo spacecraft imaged a pair of superimposed ripple patterns in 1996 and again in 2000. These patterns behave as two independent spirals.... We associate this with the Shoemaker-Levy 9 impacts of July 1994. ...Impacts by comets or their dust streams are regular occurrences in planetary rings, altering them in ways that remain detectable decades later. www.sciencemag.org/cgi/content/abstract/332/6030/711

Source:   Nancy Atkinson, Universe Today Excerpt: The formation of Saturn’s rings has been one of the classical if not eternal questions in astronomy. ... The two leading theories involve a small moon that was shattered by meteor impacts, or the tidal disruption of a comet coming too close to Saturn.  ...But one researcher has provided a provocative new theory to answer that question. Robin Canup from the Southwest Research Institute has uncovered evidence that the rings came from a large, Titan-sized moon that was destroyed as it spiraled into a young Saturn.... www.universetoday.com/75071/saturns-rings-formed-from-large-moons-destruction/

Source:   Discover Magazine   Excerpt: When I was a kid, Saturn had one big, flat ring system divided up into maybe three or four broad sections separated by gaps, and that was it. Turns out, we were wrong. Saturn has thousands of rings made up of billions upon billions of tiny ice particles. There aren’t just a handful of gaps, there are thousands of them, too, and there are moonlets in those gaps. Those tiny moons tug and pull on the rings, distorting them into weird and fantastic shapes. And "flat"? Not quite. The Cassini mission apparently delights in showing us just how wrong we were: [see photos in article] blogs.discovermagazine.com/badastronomy/2010/08/02/the-tiny-moon-with-the-long-reach/