Bright spots of Uranus' short-lived auroras have been imaged with the Hubble Space Telescope.
Bright spots of Uranus' short-lived auroras have been imaged with the Hubble Space Telescope.

Aurora, Hubble, Uranus

Hubble Reveals Curious Auroras on Uranus

13 Apr , 2012 by

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Astronomers have finally succeeded in capturing the first Earth-based images of the curious and fleeting auroras of Uranus using the Hubble Space Telescope, careful planning… and no small amount of luck.

Unlike Earthly auroras, whose long-lived curtains of glowing green, red and purple have been the subject of countless stunning photos over the past months, Uranus’ auroras are relatively dim and short-lived, lasting only several minutes at most. They were first witnessed on Uranus by Voyager 2 in 1986, but never by any Earth-based telescopes until November of 2011. Using Hubble, an international team of astronomers led by Laurent Lamy from the Observatoire de Paris in Meudon, France spotted two instances of auroras on the distant planet… once on November 16 and again on the 29th.

Two instances of Uranian aurora imaged in Nov. 2011. (L. Lamy)

Auroras are known to be created by a planet’s magnetosphere, which on Earth is aligned closely with the rotational axis — which is why auroras are seen nearest the polar latitudes. But Uranus’ magnetic field is quite offset from its rotational axis, which in turn is tipped nearly 98 degrees relative to its orbital path. In other words, Uranus travels around the Sun rolling on its side! And with a 60-degree difference between its magnetic and rotational axis, nothing on Uranus seems to point quite where it should. This — along with its 2.5-billion-mile (4 billion km) distance — makes for a “very poorly known” magnetic field.

“This planet was only investigated in detail once, during the Voyager flyby, dating from 1986. Since then, we’ve had no opportunities to get new observations of this very unusual magnetosphere,” said Laurent Lamy, lead author of the team’s paper Earth-based detection of Uranus’ aurorae.

Rather than rings of bright emissions, as witnessed on Earth as well as Saturn and Jupiter, the Uranian auroras appeared as bright spots of activity on the planet’s daytime side — most likely a result of Uranus’ peculiar orientation, as well as its seasonal alignment.

It’s not yet known what may be happening on Uranus’ night side, which is out of view of Hubble.

When Voyager 2 passed by Uranus in 1986 the planet was tipped such that its rotational axis was aimed toward the Sun. This meant that its magnetic axis —  offset by 60 degrees — was angled enough to encounter the solar wind in much the same way that Earth’s does. This created nightside auroras similar to Earth’s that Voyager saw.

By 2011, however, Uranus — which has an 84-year-long orbit — was near equinox and as a result its magnetic axis was nearly perpendicular with its orbital plane, aiming each end directly into the solar wind once a day. This makes for very different kinds of auroras than what was seen by Voyager; in fact, there’s really nothing else like it that astronomers know of.

“This configuration is unique in the solar system,” said Lamy.

Further investigations of Uranus’ auroras and magnetic field can offer insight into the dynamics of Earth’s own magnetosphere and how it interacts with the solar wind, which in turn affects our increasingly technological society.

The team’s paper will be published Saturday in Geophysical Research Letters, a journal of the American Geophysical Union.

Read the release from the AGU here.

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By  -        
A graphic designer in Rhode Island, Jason writes about space exploration on his blog Lights In The Dark, Discovery News, and, of course, here on Universe Today. Ad astra!



Sort by:   newest | oldest | most voted
Kenn Hammer
Guest
April 13, 2012 9:12 PM

ur anus

Tony Power
Guest
April 13, 2012 11:20 PM

What are you? 12? Grow up you imbecile.

Kenn Hammer
Guest
April 14, 2012 2:43 PM

wheres the humor guys..

Arnold Rimmer
Member
Arnold Rimmer
April 14, 2012 8:14 PM

you are unfunny

SJStar
Guest
SJStar
April 14, 2012 8:13 AM

ur idiot

G Money
Guest
G Money
April 13, 2012 11:44 PM

no wonder my hemorroids have been bothering me

SJStar
Guest
SJStar
April 14, 2012 8:18 AM

Sorry. I’m good at science, but am not an expert in urology. I’d suggest you go to one of those many medical sites on-line, instead.

.. .__.
Guest
April 14, 2012 1:57 AM

See my aesthetician – a little bleaching will take away that discoloration.

While you’re there, you can get that bikini wax in advance of the beach season.

John Mendenhall
Member
John Mendenhall
April 14, 2012 3:28 AM

Are the ring images real? If so, why invisible close in?

gopher65
Member
gopher65
April 15, 2012 2:15 AM

The rings are real, they’re just very faint.

John Mendenhall
Member
John Mendenhall
April 16, 2012 11:07 PM

On Sun, 15 Apr 2012 02:15:04 -0000, Disqus wrote

John Mendenhall
Member
John Mendenhall
April 16, 2012 11:07 PM

On Sun, 15 Apr 2012 02:15:04 -0000, Disqus wrote

SJStar
Guest
SJStar
April 14, 2012 6:15 AM
Thanks for the article. Uranus has been my favourite planet for a while, which seems to have new surprises. It is not as just the sterile world as the Voyage 2 apparently revealed. There is also another tiny white emission around the limb of the larger image, which aligns with the inner ring I.e. Intersect with the planet. Also seen are small variations light intensity along the limb. As for the usual childish humour nearly all of the other comments here, it no doubt explains why the Father of the gods finally ate most of his children. Most of these guys are obviously at the shallow end of the gene pool, who never exceed an education much beyond… Read more »
Kevin Frushour
Guest
April 14, 2012 6:07 PM

I THOUGHT I was above juvenile Uranus jokes. Evidently I’m not. I snickered.

Matthäus Schulik
Guest
April 14, 2012 9:46 PM
You could have of course mentioned in your article the amazingly cool method they used to track down the auroras. They followed a CME (Coronal Mass Ejection) from the sun throughout the solar system and extrapolated its time of arrival at Uranus from its encounter times with Earth and Jupiter, to be able to point Hubble there at the right moment (Observation time is short and expensive…). As your article points out auroras at Uranus are very elusive, so the increased particle densities coming with the CME were used to increase the probability of spotting one at this right time. I guess thats what you meant by “careful planning”. AND I suggest you check your sources, I’m pretty… Read more »
Jason Major
Guest
April 15, 2012 5:30 PM

True, it appears that was an HST image, not Voyager… and showed clouds, not auroras. Removed.

Prism2Spectrum
Guest
Prism2Spectrum
April 15, 2012 9:52 AM
– “But Uranus’ magnetic field is quite offset from its rotational axis, which in turn is tipped nearly 98 degrees relative to its orbital path. In other words, Uranus travels around the Sun rolling on its side! And with a 60-degree difference between its magnetic and rotational axis, nothing on Uranus seems to point quite where it should.” ______________________ Dramatic confirmation of what had been discovered, these glowing aurora of concentrated color(?)? A world tipped-over surely has input to explain the “offset” axis anomaly (either by virtue of being on its side, in relation to its Star – which could mean there is more to Magnetospheres and planetary Cores, than is known, or realized. Or from whatever powerful… Read more »
SJStar
Guest
SJStar
April 15, 2012 11:15 AM

What absolute poppycock of unrelated nonsense thickly plied with excessive verbiage !

All of this nearly totally cloaked personal theory mixed with the ramblings of crazed madman.

Where to start? Why would anyone bother?

Prism2Spectrum
Guest
Prism2Spectrum
April 15, 2012 1:10 PM
Your “Repl[ies]”, SJ, expose a ripping tone of address, that are becoming wearisome to me – and offensive. Once again, you launch into an unrestrained, personal assault against me (“crazed madman”), not just my thoughts. Shred my comments through your narrow blades of cutting words, if you wish – you are presumably given that freedom. But slapping-on insulting labels, and flinging-out oblique innuendos, are something else! Your hostility is palpable (probably not only to me). “Why would anyone bother?” Yes, SJ, why would anyone bother? Another freedom you have here, is – to skip my comments. Yet you read them (or should that be, read into them). If your boat is so easily rocked, maybe you should trade… Read more »
SJStar
Guest
SJStar
April 15, 2012 2:52 PM

Even more mindlessness. Now your even imagining you are the victim here!

Prism2Spectrum
Guest
Prism2Spectrum
April 15, 2012 1:10 PM
Your “Repl[ies]”, SJ, have ripping tones of personal address, and expose attitude of offense, that is becoming wearisome to me. Once again, you launch into an unrestrained, personal assault against me (“crazed madman”), not just my thoughts. Shred my comments through your narrow blades of cutting words, if you wish – you are presumably given that freedom. But slapping insulting labels, and flinging oblique innuendos, are something else! Your hostility is palpable (probably not only to me). “Why would anyone bother?” Yes, SJ, why would anyone bother? Another freedom you have here, is – to skip my comments. Yet you read them (or should that be, read into them). If your boat is so easily rocked, maybe you… Read more »
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