Feeds

Tiny moon ruining Saturn's day

Measuring it, anyway

Secure remote control for conventional and virtual desktops

If you were trying to work out how long a day on Saturn is, you wouldn't expect to find your best efforts scuppered by a tiny moon. After all, you can still see the planet, right?

The problem lies in the technique traditionally used to discover how fast a gas giant is rotating. The radio technique measures the rotation of the planet by taking its radio pulse rate - the rhythm of natural radio signals from the planet. If something is slowing the planet's magnetic field, this won't work.

Slowing down a giant's magnetic field. Credit: NASA/JPL

But this is exactly the problem facing scientists right now: the moon Enceladus is weighing down the gas giant's magnetic field to such an extent that the planet's field is being slowed down. This makes the radio technique as useful as a chocolate fireguard.

"No one could have predicted that the little moon Enceladus would have such an influence on the radio technique that has been used for years to determine the length of the Saturn day," said Dr Don Gurnett of the University of Iowa, principal investigator on the radio and plasma wave science experiment on NASA's Cassini spacecraft.

According to new research, published in the 22 March online issue of Science, the cause of the drag is Enceladus' polar geyser: a vast stream of ice and water vapour emanating from the moon's southern pole. These particles become electrically charged and are captured by the planet's magnetic field, forcing the field lines to slip relative to the planet's actual rotation.

The findings are prompting scientists to question the absolute link between a planet's radio pulse rate and the length of its day.

Professor Michele Dougherty, principal investigator on Cassini's magnetometer instrument from Imperial College London, says: "Saturn is showing we need to think further."

The findings explain an earlier observation that the apparent length of Saturn's day as measured by Cassini is now about six minutes longer than when it was measured by Voyager in the 1970s.

The researchers now have two possible explanations for the apparent slowing of Saturn's rotation: either the geysers are more active than they were in the 1970s, producing more material and thus slowing the field line's rotation; or there are seasonal variations according to where Saturn is in its 29 year orbit of the sun. ®

Bootnote: NASA has audio clip files to go with this. Point your ears this way and listen in on Saturn.

Boost IT visibility and business value

More from The Register

next story
Our LOHAN spaceplane ballocket Kickstarter climbs through £8000
Through 25 per cent but more is needed: Get your UNIQUE rewards!
Cutting cancer rates: Data, models and a happy ending?
How surgery might be making cancer prognoses worse
Boffins ID freakish spine-smothered prehistoric critter: The CLAW gave it away
Bizarre-looking creature actually related to velvet worms
CRR-CRRRK, beep, beep: Mars space truck backs out of slippery sand trap
Curiosity finds new drilling target after course correction
SpaceX prototype rocket EXPLODES over Texas. 'Tricky' biz, says Elon Musk
No injuries or near injuries. Flight stayed in designated area
Brit balloon bod Bodnar overflies North Pole
B-64 amateur ultralight payload approaching second circumnavigation
prev story

Whitepapers

Implementing global e-invoicing with guaranteed legal certainty
Explaining the role local tax compliance plays in successful supply chain management and e-business and how leading global brands are addressing this.
5 things you didn’t know about cloud backup
IT departments are embracing cloud backup, but there’s a lot you need to know before choosing a service provider. Learn all the critical things you need to know.
Why and how to choose the right cloud vendor
The benefits of cloud-based storage in your processes. Eliminate onsite, disk-based backup and archiving in favor of cloud-based data protection.
Top 8 considerations to enable and simplify mobility
In this whitepaper learn how to successfully add mobile capabilities simply and cost effectively.
High Performance for All
While HPC is not new, it has traditionally been seen as a specialist area – is it now geared up to meet more mainstream requirements?