First X-rays from Uranus Discovered

Composite image of Uranus.

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Astronomers have detected X-rays from Uranus for the first time, using NASA’s Chandra X-ray Observatory. This result may help scientists learn more about this enigmatic ice giant planet in our solar system.

Uranus is the seventh planet from the Sun and has two sets of rings around its equator. The planet, which has four times the diameter of Earth, rotates on its side, making it different from all other planets in the solar system. Since Voyager 2 was the only spacecraft to ever fly by Uranus, astronomers currently rely on telescopes much closer to Earth, like Chandra and the Hubble Space Telescope, to learn about this distant and cold planet that is made up almost entirely of hydrogen and helium.

In the new study, researchers used Chandra observations taken in Uranus in 2002 and then again in 2017. They saw a clear detection of X-rays from the first observation, just analyzed recently, and a possible flare of X-rays in those obtained fifteen years later. The main graphic shows a Chandra X-ray image of Uranus from 2002 (in pink) superimposed on an optical image from the Keck-I Telescope obtained in a separate study in 2004. The latter shows the planet at approximately the same orientation as it was during the 2002 Chandra observations.

What could cause Uranus to emit X-rays? The answer: mainly the Sun. Astronomers have observed that both Jupiter and Saturn scatter X-ray light given off by the Sun, similar to how Earth’s atmosphere scatters the Sun’s light. While the authors of the new Uranus study initially expected that most of the X-rays detected would also be from scattering, there are tantalizing hints that at least one other source of X-rays is present. If further observations confirm this, it could have intriguing implications for understanding Uranus.

One possibility is that the rings of Uranus are producing X-rays themselves, which is the case for Saturn’s rings. Uranus is surrounded by charged particles such as electrons and protons in its nearby space environment. If these energetic particles collide with the rings, they could cause the rings to glow in X-rays. Another possibility is that at least some of the X-rays come from auroras on Uranus, a phenomenon that has previously been observed on this planet at other wavelengths. 

On Earth, we can see colorful light shows in the sky called auroras, which happen when high-energy particles interact with the atmosphere. X-rays are emitted in Earth’s auroras, produced by energetic electrons after they travel down the planet’s magnetic field lines to its poles and are slowed down by the atmosphere. Jupiter has auroras, too. The X-rays from auroras on Jupiter come from two sources: electrons traveling down magnetic field lines, as on Earth, and positively charged atoms and molecules raining down at Jupiter’s polar regions. However, scientists are less certain about what causes auroras on Uranus. Chandra’s observations may help figure out this mystery.

Uranus is an especially interesting target for X-ray observations because of the unusual orientations of its spin axis and its magnetic field. While the rotation and magnetic field axes of the other planets of the solar system are almost perpendicular to the plane of their orbit, the rotation axis of Uranus is nearly parallel to its path around the Sun. Furthermore, while Uranus is tilted on its side, its magnetic field is tilted by a different amount, and offset from the planet’s center. This may cause its auroras to be unusually complex and variable. Determining the sources of the X-rays from Uranus could help astronomers better understand how more exotic objects in space, such as growing black holes and neutron stars, emit X-rays

A paper describing these results appears in the most recent issue of the Journal of Geophysical Research and is available online. The authors are William Dunn (University College London, United Kingdom), Jan-Uwe Ness (University of Marseille, France), Laurent Lamy (Paris Observatory, France), Grant Tremblay (Center for Astrophysics | Harvard & Smithsonian), Graziella Branduardi-Raymont (University College London), Bradford Snios (CfA), Ralph Kraft (CfA), Z. Yao (Chinese Academy of Sciences, Beijing), Affelia Wibisono (University College London).

NASA’s Marshall Space Flight Center manages the Chandra program. The Smithsonian Astrophysical Observatory’s Chandra X-ray Center controls science from Cambridge Massachusetts and flight operations from Burlington, Massachusetts.

Image credit: X-ray: NASA/CXO/University College London/W. Dunn et al; Optical: W.M. Keck Observatory

Read more from NASA’s Chandra X-ray Observatory.

For more Chandra images, multimedia and related materials, visit:

Last Updated: Apr 1, 2021Editor: Lee Mohon

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April 2, 2021 2:32 am

Me attempting self control:

Nope, I’m not gonna make a sophomoric joke about that headline.
Won’t do it.


Jeff Alberts
Reply to  Bob Tisdale
April 2, 2021 8:29 am

C’mon man! Sometimes you just have to give in to your inner sophomore.

paul courtney
Reply to  Bob Tisdale
April 2, 2021 12:42 pm

Mr. Tisdale: Thank you for your restraint. I am concerned, though, that if Uranus is getting high dose of xrays, won’t that create a high risk of rectal cancer?
I have no such restraint. H/t every eighth grade boy everywhere.

Reply to  Bob Tisdale
April 2, 2021 3:44 pm

Sagan would never pronounce it correctly…

Michael S. Kelly
Reply to  Bob Tisdale
April 2, 2021 3:56 pm
Reply to  Bob Tisdale
April 3, 2021 1:01 pm

“self control”, there is a song written about that.

Laura Branigan – Self Control (Official Music Video) – YouTube

I think it is safe for work ??

April 2, 2021 2:46 am

My money is on energetic GCRs, far more powerful, hitting the upper layers of atmosphere they create Gamma rays
the little squiggles are Feynman’s interpretations of the quantum mechanics phase process that take place during mass to energy transfers and vice versa
The ‘electromagnetic shower’ may contain all wavelengths from infra red, through visible, ultraviolet, x-rays and gamma rays.

Last edited 12 days ago by Vuk
Trying to Play Nice
April 2, 2021 4:44 am

When I saw the title I thought for sure this had to be an April Fools article, but it came out on April 2.

Reply to  Trying to Play Nice
April 2, 2021 6:08 am

I checked the date, too.

Alan M
Reply to  Chaswarnertoo
April 2, 2021 6:29 am

And me

Jeff Alberts
Reply to  Alan M
April 2, 2021 8:30 am


April 2, 2021 5:03 am

Brown dwarf?

April 2, 2021 6:43 am

the smelly jokes, they expel themselves….

Bruce Cobb
April 2, 2021 8:02 am

Why all the sophomoric laughter and jokes? You just have to pronounce it correctly: Your – ay – nus.

Jeff Alberts
Reply to  Bruce Cobb
April 2, 2021 8:31 am

I thought it was Urine-us. Hmm, just as bad.

Bruce Cobb
Reply to  Jeff Alberts
April 2, 2021 1:14 pm

Agree to disagree.

oeman 50
April 2, 2021 8:58 am

I just had mine boroscoped, not x-rayed….

April 2, 2021 8:58 am

This is good, I take NASA’s word for it.

Right-Handed Shark
April 2, 2021 9:38 am

Are NASA concerned about emissions from Uranus?

Somebody had to say it.

April 2, 2021 9:59 am

Whomever named the planet must have had a great sense of humor.

Reply to  u.k.(us)
April 2, 2021 12:00 pm

The planet was originally named Georgium, after King George III of England. It was then changed to be named after the Greek God of the Sky.

Reply to  noaaprogrammer
April 5, 2021 7:38 am

Originally named “Georges Star” it was actually named this in English, despite what you may have read from the wacky history revisers. I like the nickname “Dumbo”. I’m sure you know who first coined that 😉

Intelligent Dasein
Reply to  u.k.(us)
April 3, 2021 5:25 am

The Greek word really ought to be pronounced “Oo-RAHN-os” (which, strangely, I’ve never heard anybody actually use), and that would have averted all the silliness.

April 2, 2021 1:39 pm

This headline is worse than the 2005 headline in The Sun


April 2, 2021 4:16 pm

Uranus, the butt of many jokes.

High Treason
April 3, 2021 1:45 am

Starting to feel old, but I remember from 50 years ago we had a swear box. Swear, and you have to cough up 2 cents. My pocket money back then was 5 cents a week, with a bonus 5 cents a week because I made breakfast for myself and older and younger brothers every morning. Always the tight a***, one time I said you can stick it up… ” a planet” . The parents were curious what the term meant, so under amnesty, I told them. They loved it, with the term used to avoid copping the fine for years. Yes, ever the tight a***, I only contributed 8 cents to the swear box over several years. This was way, way, way less than anyone else. The proceeds eventually went to buy a lottery ticket. It was supposed to be named “swear box”, but they got it a*** up and called it “sugar box.”
It was NOT a winner. B*****

April 3, 2021 2:04 am

Fortunately there are couple of billion people on this planet whose native language is no English and see this poor planet for what it is rather than part of their personal anatomy. There is also radioactive chemical element of the same name but escaped attention of the English speaking schoolboys, realising it is to dangerous to ‘mess’ about with.

Last edited 11 days ago by Vuk
April 5, 2021 7:29 am

Strong polarity, The planet has an ionising field and it would have a superconducting property because the planet is so cold and dense.

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