Dwarf Planet Haumea Has a Ring

A unique opportunity to study the dwarf planet Haumea has led to an intriguing discovery: Haumea is surrounded by a ring. Add this to the already long list of unique things about the weird-shaped world with a dizzying rotation and a controversial discovery. On January 21, 2017 Haumea passed in front of a distant star, […]

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Unprecedented Views of Saturn’s Rings as Cassini Dances Death Spiral

As the Cassini spacecraft moves ever closer to Saturn, new images provide some of the most-detailed views yet of the planet’s spectacular rings. From its “Ring-Grazing” orbit phase, Cassini’s cameras are resolving details in the rings as small as 0.3 miles (550 meters), which is on the scale of Earth’s tallest buildings. On Twitter, Cassini […]

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Saturn’s Rings Continue to Surprise Scientists

Composite image of a backlit Saturn, made from Cassini images acquired on July 19, 2013. Saturn's B ring appears darkest and densest here. (NASA/JPL-Caltech/Space Science Institute)

If you try to apply simple common sense to how Saturn’s rings really work you’re going to be sorely mistaken: the giant planet’s signature features run circles around average Earthly intuition. This has been the case for centuries and is especially true now after recent news from Cassini that the most opaque sections of rings aren’t necessarily the densest; with Saturn looks literally are deceiving.

While rings are features shared by all of the gas and ice giant planets in our Solar System, Saturn is by far the “ring king” in terms of sheer magnitude, complexity, and utter beauty of its ring system. First observed through a telescope by Galileo in 1610, Saturn’s brilliant rings were initially thought by Galileo to be additional “stars,” or perhaps solid protrusions on either side of the planet like the handles of a cup. It wasn’t until 1659 that Dutch astronomer Christiaan Huygens determined that the handles were actually an encircling ring not attached to Saturn “but was separated from it the same distance all around.” (Source) And just sixteen years later Giovanni Cassini observed the largest gap in Saturn’s rings (which became his namesake feature) and correctly determined that they’re divided into sections.

While Galileo, Huygens, and Cassini all made invaluable contributions to the study of Saturn, they all assumed the rings to be solid. It was French astronomer Jean Chapelain who suggested in 1660 the rings must be made of tiny particles traveling in orbit around Saturn; however this wasn’t confirmed until the late 1850s when famed physicist James Clerk Maxwell calculated that, due to the forces of gravity and dynamical stability on such a large solid object, “the rings must consist of disconnected particles; these may be either solid or liquid, but they must be independent.” (Source)

Maxwell’s On the Stability of the Motion of Saturn’s Rings was published 100 years before Pioneer 11 gave us our first close-up views of Saturn. See a timeline of observations of Saturn’s rings here.

Fast forward to the present day.

In addition to countless observations from ground-based telescopes and space observatories like Hubble, Saturn has been flown past after Pioneer 11 by both Voyagers 1 and 2 and is currently being investigated by NASA’s Cassini spacecraft, which will soon enter its twelfth year of orbital exploration. Via the Cassini mission we’ve learned more about Saturn, its rings, and family of moons in the last decade than we had in the 394 years since Galileo first peered at it through his homemade telescope. And when it comes to its rings, researchers are learning what looks like more really is less.

Saturn’s incredibly complex ring system is divided up into distinct regions, named alphabetically outwards from the planet D, C, B, A, F, G, and E. (There’s also an enormous and diffuse infrared-visible ring surrounding Saturn at distance but we won’t get into that here.) All together these sections — each made up of bands of orbiting icy particles ranging from house-sized to finer than candle smoke — stretch a distance of 464,000 km (over 288,000 miles) from the top of Saturn’s atmosphere.. yet they’re only about ten meters (30 feet) thick.

Read more: What Are Saturn’s Rings Made Of?

One of Saturn’s ring sections — B — is much more visually opaque than the others, demonstrated both by its reflectivity and how it prevents light from background stars from easily passing through it as readily as in other rings. One might quickly conclude that such an apparently dense ring would therefore contain considerably more mass. Yet, as it turns out, that’s not the case.

Cassini measurements of density waves moving across the B ring in reaction to the gravitational pulls from nearby moons have given researchers the first accurate “weigh-in” of the ring’s core. What they found was a fairly consistent distribution of mass, regardless of any changes in opacity within the ring.

“At present it’s far from clear how regions with the same amount of material can have such different opacities. It could be something associated with the size or density of individual particles, or it could have something to do with the structure of the rings,” said Matthew Hedman in a Feb. 2 press release. Hedman is the recent study’s lead author and a Cassini participating scientist at the University of Idaho, Moscow.

And although the 25,500-kilometer-wide B ring likely does contain the most mass of all Saturn’s rings, it’s only by about a factor of two or three, despite being ten times more opaque than its outward A ring neighbor.

“Appearances can be deceiving,” noted co-investigator Phil Nicholson of Cornell University in Ithaca, New York. “A good analogy is how a foggy meadow is much more opaque than a swimming pool, even though the pool is denser and contains a lot more water.”

Makes sense. (Then again, your senses can fool you in astronomy!)

The actual mass of sections of Saturn’s rings is important in determining their age and evolution. Less material in the B ring than suspected may indicate a young age, since a “lighter” ring would evolve — and thus grow darker via meteorite impacts — quicker than a “heavier” one.

“By ‘weighing’ the core of the B ring for the first time, this study makes a meaningful step in our quest to piece together the age and origin of Saturn’s rings,” said Linda Spilker, Cassini project scientist at JPL.

Further measurements will be taken as Cassini goes into the final phase of its mission, eventually passing through the rings in 2017. The data it gathers along the way will help scientists more accurately calculate the mass and true age of the planet’s most iconic — and most enigmatic — features.

Read more in the Cassini news release here.

Source: NASA/JPL

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What Would Earth Look Like With Rings?

What would Earth look like if it had a ring system like Saturn's. Credit: Kevin Gill/Flickr

Saturn’s Rings are amazing to behold. Since they were first observed by Galileo in 1610, they have been the subject of endless scientific interest and popular fascination. Composed of billions of particles of dust and ice, these rings span a distance of about 282,000 km (175,000 miles) – which is three quarters of the distance between the Earth and its Moon – and hold roughly 30 quintillion kilograms (that’s 3.0. x 1018 kg) worth of matter.

All of the Solar System’s gas giants, from Jupiter to Neptune, have their own ring system – albeit less visible and picturesque ones. Sadly, none of the terrestrial planets (i.e. Mercury, Venus, Earth and Mars) have such a system. But just what would it look like if Earth did? Putting aside the physical requirements that it would take for a ring system to exist, what would it be like to look up from Earth and see beautiful rings reaching overhead?

It is precisely this question that inspired Kevin Gill, a software engineer who performs science data visualizations for NASA’s Jet Propulsion Laboratory, to create “Rings Over Earth”. Using vacation photos he has taken over the years, and then tweaking them with Photoshop and the 3-D animation/modeling software Maya, Gill was able to superimpose Saturn-like rings onto photographs of Earth’s skies.

In so doing, he was able to give viewers a realistic idea of what it would be like to look up at the skies and see a ring system similar to Saturn’s – specifically from the locations of New Hampshire, the San Bernadino Valley, the Griffith Observatory in Los Angeles, or Pasadena, California. And as you can see from the photos, the end result is rather breathtaking and inspiring.

The photos also show how the ring system would appear at different times of day. For instance, the photo of San Bernadino, CA, shows how the rings would appear in the sky at morning, with the Sun cresting the eastern horizon. The photo of Pasadena shows how the rings would appear at  midday, with the Sun directly overhead and illuminating the rings.

And then there are the shots taken from the Griffith Observatory that show how the rings would appear in the night sky over downtown Los Angeles. In one, we see them descending towards the glowing horizon (top), with a crescent Moon not far away. In the other (above), we see how a section of the rings has been obscured by the Earth’s shadow.

And last, but not least, there is how the rings would appear from orbit, which you can see below. No doubt, such a ring system would play havoc with orbiting satellites and space stations (such as the ISS). But as  Kevin told Universe Today via email, the project was not an exercise in plausibility, but merely for fun.

“I made [the pictures] out of a curiosity of how they would look after having done a few Saturn-related renders,” he said. “I rigged the camera, rings and Earth in Maya, placing the camera more-or-less where I indented the viewer to be (New Hampshire, Los Angeles, etc.)  I used Photoshop to composite the Maya rendered rings over photographs I had taken over the last year. Like the angles, the lighting is more-or-less approximate.”

As a full-time member of the Jet Propulsion Labority who is responsible for producing visualizations, Gill certainly understands the process of bringing data to life. But as he admits, these pictures may not be an exact rendition of what a ring system would like to an Earth-bound observer. “I didn’t do any math in preparation to get the angles exactly right,” he said. “In fact, in one of the images, I actually moved the Moon out to the right of where it actually was to simulate a more ‘southerly’ view.”

However, there is a fair degree of scientific merit to this kind of artistic speculation. For starters, it is widely believed that at one time, Earth had a ring system of sorts, which was the result of a cataclysmic impact. This is part of what is known as the Impact Hypothesis of the Moon’s formation, where a newly-formed Earth was struck by a Mars-sized object named Theia roughly 4.5 billion years ago.

This collision ejected material into orbit, which would have formed into a ring around the planet. As this ring fell outside of Earth’s Roche Limit, the force of mutual attraction caused thse particles to accrete to form the Moon, which was then able to hold together.

Had it been outside of Earth’s Roche Limit, this material would have not been able to come together and would therefore have remained as a disc. This is the case for Saturn, which maintains a beautiful ring system within it’s Roche Limit, and several moons beyond it.

So while Earth, in some alternate reality, could have had a ring system, we would have paid for it by never having the Moon. Hence, there would have never been an Apollo Program, and we would not be currently contemplating building settlements there someday. Doesn’t exactly seem like a fair exchange does it?

But I think we can all agree, the idea of a ring system around Earth (and some artistic renderings of what it would look like) makes from some pretty nice viewing! And Gill is not the first to create photos that imagine what Earth would look like if it had rings. In 2013, veteran astronomy artist Ron Miller created a series of illustrations of a ringed Earth. As former art director at the National Air & Space Museum’s Albert Einstein Planetarium, Miller has been responsible for producing countless visualizations of what other planets would look like to the casual observer. You can view his artwork here.

And back in 2009, information provided by NASA”s Cassini space probe led to a number of animators producing videos of what Earth would look like with rings. One such artist was Roy Prol (aka. T0R0YD), who used 3DS Max to show how the rings would appear in the sky from different latitudes on Earth. Clearly, we all wonder what our planet would look like if it were a little less “Earth-like”!

Be sure to can check out Kevin Gill’s gallery on Flickr, as well as other works of astronomy-related artwork.

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“Super Saturn” Has an Enormous Ring System and Maybe Even Exomoons

Astronomers watching the repeated and drawn-out dimming of a relatively nearby Sun-like star have interpreted their observations to indicate an eclipse by a gigantic exoplanet’s complex ring system, similar to Saturn’s except much, much bigger. What’s more, apparent gaps and varying densities of the rings imply the presence of at least one large exomoon, and perhaps even more in the […]

“Super Saturn” Has an Enormous Ring System and Maybe Even Exomoons

Astronomers watching the repeated and drawn-out dimming of a relatively nearby Sun-like star have interpreted their observations to indicate an eclipse by a gigantic exoplanet’s complex ring system, similar to Saturn’s except much, much bigger. What’s more, apparent gaps and varying densities of the rings imply the presence of at least one large exomoon, and perhaps even more in the […]