Mystery of the half-mile-wide objects plunging into Saturn’s rings

Hundreds of objects up to half a mile in diameter have been caught on camera wreaking havoc with one of Saturn’s rings.

The objects are actually snowballs created by some of Saturn’s 60 moons, like Prometheus.

They have been snapped punching through Saturn’s F ring, the outermost of the planet’s main rings, with a radius of about 87,000 miles.

Cassini has captured amazing images of snowballs punching through Saturn's F ring

Spectacular show: From left to right in the top row, the trails in these images are 18, 85 and 96 miles long. In the bottom row from left to right, the trails are 43, 129 and 32 miles long.

Rounding out the facts: The constant change in Saturn's wavy, wiggly F ring is on display in this set of images

Rounding out the facts: The constant change in Saturn’s wavy, wiggly F ring is on display in this set of images

SATURN FACTS

Saturn lies 890 million miles from the Sun on average.

It has a diameter of 74,897 miles.

It’s a very very cold planet, with an average temperature of -140C (-220F).

It’s made of liquid and solid hydrogen and helium and is so light it would float on water.

It’s most famous for its rings, which were first discovered in the 17th-century. They extend 46,000 miles out and have a total diameter of almost 170,000 miles.

It has 60 moons – more than any other planet in the solar system, bar Jupiter. One of them, Titan, is the second largest in the solar system and actually has an atmosphere – composed mainly of nitrogen.

Saturn is extremely stormy, with winds gusting at 1,000mph at the equator.

‘I think the F ring is Saturn’s weirdest ring, and these latest Cassini results go to show how the F ring is even more dynamic than we ever thought,’ said Carl Murray, a Cassini imaging team member based at Queen Mary University of London. ‘These findings show us that the F ring region is like a bustling zoo of objects from a half mile in size to moons like Prometheus a hundred miles in size, creating a spectacular show.’

Scientists have known that relatively large objects like Prometheus (as long as 92 miles, or 148 kilometres, across) can create channels, ripples and snowballs in the F ring.

But scientists didn’t know what happened to these snowballs after they were created, Murray said.

Some were surely broken up by collisions or tidal forces in their orbit around Saturn, but now scientists have evidence that some of the smaller ones survive, and their differing orbits mean they go on to strike through the F ring on their own.

These small objects appear to collide with the F ring at gentle speeds – something on the order of about 4mph (two metres per second).

The collisions drag glittering ice particles out of the F ring with them, leaving a trail typically 20 to 110 miles (40 to 180 kilometres) long.

Murray’s group happened to see a tiny trail in an image from January 30, 2009 and tracked it over eight hours.

The long footage confirmed the small object originated in the F ring, so they went back through the Cassini image catalogue to see if the phenomenon was frequent.

Stunning: Saturn's rings stretch 46,000 miles into space

Stunning: Saturn’s rings stretch 46,000 miles into space

‘The F ring has a circumference of 550,000 miles (881,000 kilometres), and these mini-jets are so tiny they took quite a bit of time and serendipity to find,’ said Nick Attree, a Cassini imaging associate at Queen Mary. ‘We combed through 20,000 images and were delighted to find 500 examples of these rogues during just the seven years Cassini has been at Saturn.’

In some cases, the objects travelled in packs, creating mini-jets that looked quite exotic, like the barb of a harpoon.

Other new images show grand views of the entire F ring, showing the swirls and eddies that ripple around the ring from all the different kinds of objects moving through and around it.

‘Beyond just showing us the strange beauty of the F ring, Cassini’s studies of this ring help us understand the activity that occurs when solar systems evolve out of dusty disks that are similar to, but obviously much grander than, the disk we see around Saturn,’ said Linda Spilker, Cassini project scientist based at Nasa’s Jet Propulsion Laboratory in Pasadena, California.

‘We can’t wait to see what else Cassini will show us in Saturn’s rings.’

 

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s