NASA has photos of Uranus

Uranus in the X-ray light

The distant planet Uranus appears as colorful as an Easter egg. But what comes across here in such a poppy pink is an astronomical premiere. Because the pink spots mark X-rays that emanate from Uranus - it is their first detection on this planet. It remains to be seen whether the X-ray radiation emanates from the planet itself or is only reflected by it.

Uranus and its neighbor Neptune are among the most puzzling and strange planets in our solar system. Their interior contains exotic ice shapes, their magnetic field has four instead of the usual two poles and apart from Voyager-2 no probe has come really close to them. Uranus is also unique because it orbits the sun lying on its side - possibly as a result of a planetary catastrophe.

Diffuse X-ray glow and punctual breakouts

Now there is news from Uranus: Astronomers have succeeded in capturing X-rays from the distant ice giant for the first time. They tracked down the signal of this radiation in data from NASA's Chandra X-ray telescope from 2002 and 2017. Current analyzes have shown that the planet was already emitting diffuse X-rays in 2002 - recognizable as a pink area in the image. In 2017, the telescope even detected selective X-ray bursts on Uranus.

But where does this radiation come from? One possible explanation would be the reflection of X-rays from the sun. Astronomers have already detected such backscattering from the gas giants Jupiter and Saturn. While this also seems plausible for Uranus, this alone cannot explain all X-ray signals, as the researchers report. Their data provide evidence that there must be at least one other X-ray source on or on the planet.

One possibility would be that the thin rings of Uranus give off the X-rays. Because when charged particles from the planet's ionosphere hit the icy particles of the rings, this can lead to the excitation of the particles, which then release X-rays. Another source could be the northern lights of Uranus. We know from Jupiter that a glow in the X-ray range can also be seen. In view of the highly complex four-pole magnetic field around Uranus, however, little research has been carried out into how exactly his aurors are formed. The X-rays could now possibly help. (Journal of Geophysical Research: Space Physics, 2021; doi: 10.1029 / 2020JA028739)

Source: Harvard-Smithsonian Center for Astrophysics

April 1, 2021

- Nadja Podbregar