Glowing aurora lights on Uranus help scientists determine a day is 28 seconds longer on sideways planet
A full rotation or "day" on Uranus is 17 hours, 14 minutes and 52 seconds long – 28 seconds longer than the estimate calculated from Voyager 2 data in 1986.
Discovering Uranus
Uranus was discovered 241 years ago.
Space weather creates the Northern Lights on Earth, and more recently, aurora lights on Uranus helped NASA’s Hubble Space Telescope measure the planet’s interior rotation rate, changing what astronomers know about how long a day is on the cold and windy world.
Previous estimates of Uranus’ rotation rate came from NASA’s Voyager 2 spacecraft flyby in 1986. However, more recent observations using the mighty Hubble Space Telescope and a new technique have found that the estimate was just a little off by about half a minute.
URANUS ISN’T AS WEIRD AS SCIENTISTS THOUGHT; IT JUST TOOK NEARLY 40 YEARS TO FIND OUT WHY
This visual showcases 3 images from the NASA/ESA Hubble Space Telescope of the dynamic aurora on Uranus in October 2022. These observations were made by the Space Telescope Imaging Spectrograph (STIS) and includes both visible and ultraviolet data. (ESA/Hubble, NASA, L. Lamy, L. Sromovsky / NASA)
Astronomer Laurent Lamy with the Laboratory for Instrumentation and Research in Astrophysics (LIRA) in Paris developed a new technique to track the rotational motion of the aurora on Uranus using Hubble. These light displays are generated in the upper atmosphere from energetic particles near the planet’s magnetic poles. According to those findings, a full rotation or "day" on Uranus is 17 hours, 14 minutes and 52 seconds long, which is 28 seconds longer than the estimate calculated from Voyager 2 data in 1986.
Auroras are a known phenomenon on Earth, Jupiter and Saturn. However, unlike these other planets, the glowing lights on Uranus are unique because of their unpredictable manner, which is due to the planet's tilted magnetic field.
Thankfully, Hubble has observed these aurora emissions on the sideways planet for more than a decade, allowing astronomers to track the positions of the magnetic poles.
ASTRONOMERS REVEAL WHAT URANUS AND NEPTUNE REALLY LOOK LIKE
This Hubble image shows Uranus and dynamic aurora activity on October 10, 2022. (ESA/Hubble, NASA, L. Lamy, L. Sromovsky / NASA)
"Our measurement not only provides an essential reference for the planetary science community but also resolves a long-standing issue: previous coordinate systems based on outdated rotation periods quickly became inaccurate, making it impossible to track Uranus’ magnetic poles over time," Lamy said. "With this new longitude system, we can now compare auroral observations spanning nearly 40 years and even plan for the upcoming Uranus mission."
Robotic missions could reveal more secrets of Uranus in the next decade. The planet is considered a high priority for NASA and the European Space Agency. NASA plans to explore a possible flagship mission, including an orbiter to Uranus and a probe dropped into the atmosphere.