In an examination and with further analysis, they saw clear detection of X-rays from the first observation and possible flare of X-rays from those 15 years later.
Uranus at approximately the same orientation as it was during the 2002 Chandra observations. 2017 HRC Composite Image (Credit: X-ray: NASA/CXO/University College London/W. Dunn et al; Optical: W.M. Keck Observatory)
Astronomers have previously observed that both jupiter” target=”_blank”>Jupiter< scatter X-ray light from the sun.
However, while the study’s authors say they believe the X-rays detected would also be from “scattering,” another source of X-rays is also likely.
Like Saturn, they say, Uranus’ rings could be producing the X-rays itself or even the planet’s aurora — a phenomenon created when high-energy particles interact with the atmosphere.
“Uranus is surrounded by charged particles such as electrons and protons in its nearby air-and-space” target=”_blank”>space environment<. “If these energetic particles collide with the rings, they could cause the rings to glow in X-rays.”
X-rays are emitted in Earth’s auroras and Jupiter has auroras, as well, though X-rays from auroras on Jupiter come from two sources.
However, a nearly identical NASA release notes that researchers remain uncertain about what causes the auroras on Uranus.
The agency wrote that the unusual orientations of its spin axis and magnetic field may cause the planet’s auroras to be “unusually complex and variable.”
The rotation axis of Uranus is nearly parallel to its path around the sun — unlike the axes of other planets in the solar system — and while Uranus is tilted on its side, its magnetic field is tiled by a different amount.
“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,” NASA wrote.
Uranus is the seventh planet from the sun in the solar system. It has two sets of rings around its equator. Its diameter is four times that of Earth.
Because Voyager 2 was the only spacecraft to ever fly by Uranus, astronomers rely on telescopes like Chandra to learn more about the cold planet that is made up almost entirely of hydrogen and helium.