{"id":31755,"date":"2019-01-25T03:38:32","date_gmt":"2019-01-25T11:38:32","guid":{"rendered":"http:\/\/www.jewishindependent.ca\/?p=31755"},"modified":"2019-01-24T10:29:43","modified_gmt":"2019-01-24T18:29:43","slug":"cassinis-view-of-saturn","status":"publish","type":"post","link":"https:\/\/www.jewishindependent.ca\/index.php\/2019\/01\/25\/cassinis-view-of-saturn\/","title":{"rendered":"Cassini\u2019s view of Saturn"},"content":{"rendered":"\n

Saturn\u2019s main rings, along with its\nmoons, are much brighter than most stars. As a result, much shorter exposure\ntimes (10 milliseconds, in this case) are required to produce an image and not\nsaturate the detectors of the imaging cameras on Cassini. A longer exposure\nwould be required to capture the stars as well. (photo from NASA\/JPL-Caltech\/Space\nScience Institute)<\/em><\/strong>
<\/p>\n\n\n\n

Grand Finale was the official name of Cassini\u2019s\nlast act: a risky orbit between Saturn\u2019s rings and atmosphere in an attempt to\nexplore the planet up close, right before the craft went up in flames.<\/p>\n\n\n\n

Prof. Yohai Kaspi and Dr. Eli Galanti of the Weizmann\nInstitute\u2019s earth and planetary sciences department led one of the studies on\nCassini\u2019s final mission, revealing the depth of Saturn\u2019s jet streams \u2013 the\nstrongest measured in the solar system, with winds of up to 1,500 kilometres\nper hour \u2013 and found them to reach a depth of around 9,000 kilometres. Teaming\nup with research partners in Italy and the United States, their study also\nhelped reveal the age of the planet\u2019s rings. The findings of these studies were\npublished this month in Science<\/em>.<\/p>\n\n\n\n

Cassini was one of the more successful\nplanetary missions, orbiting and returning information on Saturn and its moons\nfor the last 20 years. As the mission was approaching its end, it was decided\nto end its life with a non-circular orbit swinging in very close to the planet,\nfollowed by a final plunge into the gaseous mass. Kaspi and Galanti joined the\nCassini team following their work as part of NASA\u2019s Juno science team, which\nhad employed a similar orbit to produce the most reliable measurements yet of\nJupiter\u2019s atmospheric depth. The Cassini scientists thought it would be\npossible to do the same for Saturn, and the Weizmann scientists were called in\nto apply their methodology to the Saturn measurements.<\/p>\n\n\n\n

Kaspi described the challenge: \u201cWe detect small\nvariations in the gravity field as the craft orbits Saturn, and translate these\ninto the atmospheric wind that produces them. There was no guarantee it would\nwork for Saturn, as the gravity signal on Saturn is more difficult to interpret\nthan what we had on Jupiter. We discovered that not only did it work for both\nplanets, but that same physical processes control the depth of the flows on\nthese two planets.\u201d<\/p>\n\n\n\n

To calculate the depth of the winds, the\ngravity measurements undertaken by Cassini were analyzed with the theoretical\nmodel developed by the Weizmann researchers. \u201cWe also teamed up with a second\ngroup investigating the internal structure of the planet,\u201d said Galanti.\n\u201cTogether, we calculated that the depth of the atmosphere is up to around 9,000\nkilometres. That is three times deeper than that of Jupiter. We also found\nthat, just as on Jupiter, a strong internal magnetic field is what limits the\ndepth of this layer of the atmosphere. Our theory worked twice, which provides\nstrong support for its validity.\u201d<\/p>\n\n\n\n

In the same study, the researchers analyzed the\nGrand Finale data from Saturn\u2019s rings, finding they are at most 100 million\nyears old. That is quite recent in the 4.5-billion-year history of the solar\nsystem. The planet in the night sky at the time of the first dinosaurs was,\napparently, without the rings we know today.<\/p>\n\n\n\n

For more on the research being conducted at the Weizmann Institute, visit wis-wander.weizmann.ac.il<\/a>. <\/p>\n\n\n\n

\u2013 Weizmann Institute<\/em><\/p>\n\n\n\n

Saturn losing its rings<\/strong><\/h4>\n\n\n\n

New NASA research confirms that Saturn is\nlosing its iconic rings at the maximum rate estimated from Voyager 1 and 2\nobservations made decades ago. The rings are being pulled into Saturn by\ngravity as a dusty rain of ice particles under the influence of Saturn\u2019s\nmagnetic field.<\/p>\n\n\n\n

\"photo
Saturn\u2019s northern hemisphere in 2016, as that part of the planet nears its northern hemisphere summer solstice in May 2017. Since NASA\u2019s Cassini spacecraft arrived at Saturn in mid-2004, the shifting angle of sunlight as the seasons march forward has illuminated the giant hexagon-shaped jet stream around the north polar region, and the subtle bluish hues seen earlier in the mission have continued to fade. (photo from NASA\/JPL-Caltech\/Space Science Institute)<\/em><\/figcaption><\/figure><\/div>\n\n\n\n

\u201cWe estimate that this \u2018ring rain\u2019 drains an\namount of water products that could fill an Olympic-sized swimming pool from\nSaturn\u2019s rings in half an hour,\u201d said James O\u2019Donoghue of NASA\u2019s Goddard Space\nFlight Centre in Greenbelt, Md. \u201cFrom this alone, the entire ring system will be\ngone in 300 million years, but add to this the Cassini-spacecraft measured\nring-material detected falling into Saturn\u2019s equator, and the rings have less\nthan 100 million years to live. This is relatively short, compared to Saturn\u2019s\nage of over four billion years.\u201d O\u2019Donoghue is lead author of a study on\nSaturn\u2019s ring rain appearing in Icarus<\/em> Dec. 17.<\/p>\n\n\n\n

Scientists have long wondered if Saturn was\nformed with the rings or if the planet acquired them later in life. The new\nresearch favours the latter scenario, indicating that they are unlikely to be\nolder than 100 million years, as it would take that long for the C-ring to\nbecome what it is today assuming it was once as dense as the B-ring. \u201cWe are\nlucky to be around to see Saturn\u2019s ring system, which appears to be in the\nmiddle of its lifetime. However, if rings are temporary, perhaps we just missed\nout on seeing giant ring systems of Jupiter, Uranus and Neptune, which have\nonly thin ringlets today,\u201d O\u2019Donoghue added.<\/p>\n\n\n\n

Various theories have been proposed for the ring\u2019s\norigin. If the planet got them later in life, the rings could have formed when\nsmall, icy moons in orbit around Saturn collided, perhaps because their orbits\nwere perturbed by a gravitational tug from a passing asteroid or comet.<\/p>\n\n\n\n

\u2013 NASA Goddard Space Flight Centre<\/em><\/p>\n","protected":false},"excerpt":{"rendered":"

Saturn\u2019s main rings, along with its moons, are much brighter than most stars. As a result, much shorter exposure times (10 milliseconds, in this case) are required to produce an image and not saturate the detectors of the imaging cameras on Cassini. A longer exposure would be required to capture the stars as well. (photo […]<\/p>\n","protected":false},"author":2,"featured_media":31756,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[8666,7246,8665,2225,4381],"class_list":["post-31755","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-world","tag-cassini","tag-nasa","tag-saturn","tag-science","tag-weizmann-institute"],"blocksy_meta":{"styles_descriptor":{"styles":{"desktop":"","tablet":"","mobile":""},"google_fonts":[],"version":8}},"_links":{"self":[{"href":"https:\/\/www.jewishindependent.ca\/index.php\/wp-json\/wp\/v2\/posts\/31755","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.jewishindependent.ca\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.jewishindependent.ca\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.jewishindependent.ca\/index.php\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.jewishindependent.ca\/index.php\/wp-json\/wp\/v2\/comments?post=31755"}],"version-history":[{"count":0,"href":"https:\/\/www.jewishindependent.ca\/index.php\/wp-json\/wp\/v2\/posts\/31755\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.jewishindependent.ca\/index.php\/wp-json\/wp\/v2\/media\/31756"}],"wp:attachment":[{"href":"https:\/\/www.jewishindependent.ca\/index.php\/wp-json\/wp\/v2\/media?parent=31755"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.jewishindependent.ca\/index.php\/wp-json\/wp\/v2\/categories?post=31755"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.jewishindependent.ca\/index.php\/wp-json\/wp\/v2\/tags?post=31755"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}