The presence of an infrared aurora on the cold, outer planet of Uranus has been confirmed for the first time by University of Leicester astronomers.
The discovery could shed light on the mysteries behind the magnetic fields of the planets of our solar system, and even on whether distant worlds might support life.
The team of scientists, supported by the Science and Technology Facilities Council (STFC), have obtained the first measurements of the infrared (IR) aurora at Uranus since investigations began in 1992. While the ultraviolet (UV) aurorae of Uranus has been observed since 1986, no confirmation of the IR aurora had been observed until now. The scientists’ conclusions have been published in the journal Nature Astronomy.
The ice giants Uranus and Neptune are unusual planets in our solar system as their magnetic fields are misaligned with the axes in which they spin. While scientists have yet to find an explanation for this, clues may lie in Uranus’s aurora.
Aurorae are caused by highly energetic charged particles, which are funnelled down and collide with a planet’s atmosphere via the planet’s magnetic field lines. On Earth, the most famous result of this process are the spectacles of the Northern and Southern Lights. At planets such as Uranus, where the atmosphere is predominately a mix of hydrogen and helium, this aurora will emit light outside of the visible spectrum and in wavelengths such as the infrared (IR).
The team used infrared auroral measurements taken by analysing specific wavelengths of light emitted from the planet, using the Keck II telescope. From this, they can analyse the light (known as emission lines) from these planets, similar to a barcode. In the infrared spectrum, the lines emitted by a charged particle known as H3+ will vary in brightness depending on how hot or cold the particle is and how dense this layer of the atmosphere is. Hence, the lines act like a thermometer into the planet.
Their observations revealed distinct increases…