Giant methane storms on Uranus

March 2, 2015 by Helen Maynard-Casely, The Conversation
Uranus as seen by NASA’s Voyager 2 Credit: NASA/JPL-Caltech

Most of the times we have looked at Uranus, it has seemed to be a relatively calm place. Well, yes its atmosphere is the coldest place in the solar system. But, when we picture the seventh planet in our solar system invariably the image of a calming blue hazy disc that the spacecraft Voyager 2 took in 1986 comes to mind.

However, all we have previously known about the atmosphere of Uranus has been 'thrown to the wind' with observations made last year.

In August 2014 a group led by Imke de Pater pointed the Keck telescope at Uranus and were a little bit surprised to see storms raging. It wasn't as though clouds haven't been seen before, but the clouds they spotted last year were very much brighter than any seen before. The fact that the storms are bright in the methane spectrum isn't a surprise – Uranus, and its neighbour Neptune, are pretty much just big balls of methane, water and ammonia (but it does make for a snigger-worthy headline).

The storms are described in a paper recently published in Icarus, with the pre-print available here. After the first observations, the group put out a call to amateur astronomers to see if they could also observed this unusual activity too. They did, and with this information the group built a case to point the Hubble Space telescope at Uranus, which happened in October. Again, they saw large storms, showing that what they had seen in August hadn't been a one off event - the weather report on Uranus is looking rather unsettled.

Light from Uranus, as captured from my backyard in Sydney. The dips in the spectrum mainly correspond to methane (positions of the methane absorption is shown by the blue lines). Credit: Andy Casely

Uranus was the first planet to be discovered in the 'recent' era of science. All the planets up to Saturn were observed to be different 'wandering' stars by many ancient cultures – so we'll never know who first spotted them. But Uranus was first observed in 1690 by John Flamsteed. He plotted it six times – but didn't realise it was different from any other star (he catalogued it to be 64 Tauri). The French astronomer Pierre Lemonnier also observed Uranus, but didn't distinguish it from the other stars he was watching. It was William Herschel who realised, in 1781 after thinking it was a comet, that he'd seen a planet orbiting further from the sun than Saturn.

Despite knowing where it was for over 300 years, we've only in the last decade started to take a detailed view of the Northern hemisphere of Uranus. The observations made by de Pater and her team are the first time this giant region of our has been surveyed by modern telescopes from Earth. This is because of the very strange rotation, which makes Uranus pretty unique.

Our Earth rotates on its axis tilted only slightly from being straight up (if we define up as being perpendicular to a planet's orbital plane). It is this tilt that drives our seasons.

Uranus has the most extreme tilt of axis in the whole solar system, it is inclined 98° from up. This means Uranus has the most extreme seasons – as each hemisphere of the planet faces the sun as it orbits (a cycle that take 84 years). The upshot is that as the Northern hemisphere has been in winter until recently, and from Earth we have been unable to see it. In 2007 Uranus reached it's equinox, with the equator pointing at the sun and each of the two hemispheres illuminated.

The storms on Uranus, as seen from the Keck telescope. Credit: Imke de Pater (UC Berkeley), Larry Sromovosky and Pat Fry (U. Wisconsin), and Heidi Hammel (AURA)

The group observed Uranus with the Keck telescope as it past equinox seven years ago. They expected to see storm activity, as parts of the planet that haven't seen the sun in 20 years started to come to light. They thought it has gone quiet again, which is why 2014's storms took them by surprise. Added to this is the fact the storms are flaring up in the Northern hemisphere, the part of Uranus that is entering its spring, and thought not to have warmed up from its prolonged winter yet.

Where is the energy to drive these storms coming from? That's the mystery. Storms on the other gas giants are thought to be fed by energy from their dynamic interiors. Voyager 2 saw that Uranus should have a dynamic interior (it has an active magnetic field like Neptune) but that little of this energy is reaching the atmosphere. This is why Uranus is the coldest planet in our solar system, parts of the atmosphere were observed to be a chilly -224°C.

Uranus' strange orbit explained. Credit: M. Showalter/M. Gordon/SETI Institute

What this observation of these giant storms really does highlight, is just how little we know about our solar system's giant icy planets Uranus, and its neighbour Neptune. In the light of the fact that missions like Kepler are finding many other similar planets orbiting distant stars, we really need to sort this out. Hopefully knowing more about our 'local' planets will mean that we can understand much more about those further away.

Meanwhile, while we in Australia may have past our summer – think of the Southern hemisphere of Uranus where a 20-year winter is coming….

Explore further: Cassini spies the ice-giant planet Uranus

Related Stories

Cosmic matters: Stormy weather on Uranus

August 7, 2014

(Phys.org) —Weather on any planet can be quite unpredictable. As hurricanes threaten the Aloha State, astronomers working at W. M. Keck Observatory on the island of Hawaii were surprised by the appearance of gigantic swirling ...

Astronomers thrilled by extreme storms on Uranus

November 12, 2014

The normally bland face of Uranus has become increasingly stormy, with enormous cloud systems so bright that for the first time ever, amateur astronomers are able to see details in the planet's hazy blue-green atmosphere.

Clues revealed about hidden interior of Uranus

November 14, 2014

(Phys.org) —Long believed to be one of the blandest regions of any of the giant gas planets, the southern hemisphere of Uranus indicates a flurry of previously unknown atmospheric phenomena, hinting at an unusual feature ...

Dance of the planets in the evening sky

February 19, 2015

Armagh Observatory reports that the next two weeks provide a rare opportunity to observe the planets Venus, Mars and Uranus in the western evening sky after sunset, and the bright planet Jupiter rising high in the East about ...

Recommended for you

Spitzer Space Telescope begins 'Beyond' phase

August 26, 2016

Celebrating the spacecraft's ability to push the boundaries of space science and technology, NASA's Spitzer Space Telescope team has dubbed the next phase of its journey "Beyond."

NASA's Juno to soar closest to Jupiter this Saturday

August 26, 2016

This Saturday at 5:51 a.m. PDT, (8:51 a.m. EDT, 12:51 UTC) NASA's Juno spacecraft will get closer to the cloud tops of Jupiter than at any other time during its prime mission. At the moment of closest approach, Juno will ...

Rosetta captures comet outburst

August 25, 2016

In unprecedented observations made earlier this year, Rosetta unexpectedly captured a dramatic comet outburst that may have been triggered by a landslide.

14 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

Rute
2.8 / 5 (4) Mar 02, 2015
Very interesting. In addition to looking at the planet with telescopes, they should send probes into Uranus to get a closer whiff at the situation.
24volts
4 / 5 (2) Mar 02, 2015
Theory - you guys can laugh if you want to! :)
Uranus has a magnetic field so probably has a molten core covered by rock like Earth does. At that distance it also probably has a fairly thick coating of ice water-methane-ammonia mix and would be basically smooth and not have mountain ranges. Since that planet is spinning fast enough that a spot on the surface is traveling roughly 7 times as fast as an equivalent spot on Earth at the equator could it be possible that it's smooth surface simply builds up really huge static charges between the surface and the atmosphere? Possibly causing those huge lit up storm spots in the picture. I think a lightening strike there would be much bigger than one here on this planet. Like I said, just a theory....
cantdrive85
1 / 5 (5) Mar 03, 2015
Where is the energy to drive these storms coming from? That's the mystery.


It's only a mystery if you disregard the electrical effects the Sun has on it's planets.
vlaaing peerd
4 / 5 (4) Mar 03, 2015
Theory - you guys can laugh if you want to! :)


Think all you want, but better to just refer to it as "a thought" A theory in science is usually regarded as an already proven set of rules.

It's not that a crazy thought either, I think on some forums and encyclopedia's you should be able to find conclusive answers about the properties of Uranus' make up and atmosphere and narrow it down from there.

ryggesogn2
not rated yet Mar 03, 2015
Is the headline written by comedian?
Maggnus
4.2 / 5 (5) Mar 03, 2015
Theory - you guys can laugh if you want to! :)
Uranus has a magnetic field so probably has a molten core covered by rock like Earth does. At that distance it also probably has a fairly thick coating of ice water-methane-ammonia mix and would be basically smooth and not have mountain ranges. Since that planet is spinning fast enough that a spot on the surface is traveling roughly 7 times as fast as an equivalent spot on Earth at the equator could it be possible that it's smooth surface simply builds up really huge static charges between the surface and the atmosphere? Possibly causing those huge lit up storm spots in the picture. I think a lightening strike there would be much bigger than one here on this planet. Like I said, just a theory....

Look up "metallic hydrogen", you may come up with a newer theory.
reset
1 / 5 (4) Mar 03, 2015
Look up "metallic hydrogen", you may come up with a newer theory.


Until it's proven to exist, you might want to as well.
wduckss
not rated yet Mar 03, 2015
Theory - you guys can laugh if you want to! :)
Uranus has a magnetic field so probably has a molten core covered by rock like Earth does.


Little impact, the data do not support, as opposed to the Neptune and Jupiter. The winds are moving in the direction of rotation, which could be the answer.
yyz
4.4 / 5 (7) Mar 03, 2015
A couple of recent papers on the recent storm activity on Uranus:

http://arxiv.org/...03.00592

http://arxiv.org/...01.01309

Bonus: both papers are relatively straightforward/easy to follow and both have awesome images of the recent storms on the planet courtesy of Keck, Gemini and HST!
antigoracle
4.2 / 5 (5) Mar 03, 2015
Hmm... quite the mother lode of information on Uranus, and just from telescopes. So, imagine if they sent a probe up there.
Whydening Gyre
4.4 / 5 (7) Mar 03, 2015
Hmm... quite the mother lode of information on Uranus, and just from telescopes. So, imagine if they sent a probe up there.

Are you sayin' - "It's probin' time..." for Uranus?
reset
3 / 5 (2) Mar 05, 2015
Hmm... quite the mother lode of information on Uranus, and just from telescopes. So, imagine if they sent a probe up there.

Are you sayin' - "It's probin' time..." for Uranus?


Beautiful.
Steve 200mph Cruiz
5 / 5 (4) Mar 08, 2015
Reset

Metallic hydrogen was first synthesized in 1996 at Lawrence Livermore National Laboratory on accident by putting over a million atmospheres on it and heating the hydrogen.
It would be a serious problem if it didn't exist because it would break patterns in the periodic table, our understanding of electromagnetism, and it would remove any explanation of why Jupiter's magnetic field is so awesome.
FastEddy
1 / 5 (2) Mar 09, 2015
Not really news ... But it IS global warming.

All of the planets have been experiencing this kind of "Climate Change" for several years, ever since the Sun stopped producing so many Sun spots. Jupiter, too, lost The Great Spot (storm) just a few years ago, now there are a bunch of small Jupiter spots/storms there.
( suspicious0bservers.org for daily Sun spot updates to this info.)

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.