NASA has released a composite image created from observations made by the Voyager 2 probe and the Hubble Space Telescope, displaying intense auroras glowing in the atmosphere of the icy planet Uranus.
Auroras on Earth are spectacular to behold, streaking and illuminating the skies with brilliant ethereal colors that are visible near the magnetic poles both to people on the ground, and also to astronauts orbiting 250 miles (400 km) above the planet aboard the International Space Station.
The phenomenon occurs on Earth when charged particles emanating from the Sun are channeled into the upper atmosphere by the planet's magnetic field. Once in the atmosphere, the charged particles interact with gas particles, including nitrogen and oxygen, which triggers bursts of light.
However, Earth is not the only planet with an atmosphere and magnetic field capable of putting on a show. Auroras have been discovered around several other bodies in the solar system, including Mars and Jupiter. As on Earth, the display can be caused by a bombardment of charged particles emanating from the Sun, but they can also be influenced by volcanic outbursts, as is the case with the Jovian moon Io.
Planets are not the only heavenly bodies on which aurora are known to manifest, and the phenomenon has also been observed to occur on some moons. In 2015, Hubble spotted an ultraviolet aurora on the Jovian moon Ganymede, which hinted at the presence of a vast subsurface ocean containing more water than all of Earth's surface oceans combined.
Auroras were first detected around Uranus, the icy seventh planet from the Sun, back in 2011. The new release is the result of follow up observations carried out using Hubble's Space Telescope Imaging Spectrograph in 2012 and 2014, supplemented by shots from NASA's Voyager 2 probe.
The latest Hubble shots of the auroras were the most intense ever recorded on Uranus, and by observing the events over time, scientists were able to collect direct evidence that the features rotate along with the planet, rather than remaining stationary.
Source: NASA