Researchers tracking the motion of Uranus' auroras have found that its rotation period is 28 seconds longer than previously thought. (Image credit: ESA/Hubble, NASA, L. Lamy, L. Sromovsky)
A new study shows that a day on Uranus lasts about half a minute longer than previously estimated.
An analysis of 11 years of data collected by the Hubble Space Telescope suggests that a day on Uranus is 17 hours, 14 minutes and 52 seconds long. That's 28 seconds longer than NASA's Voyager 2 spacecraft estimated during its flyby of Uranus in 1986. The updated data were published April 7 in the journal Nature Astronomy.
Almost 40 years ago, Voyager 2 became the first spacecraft to make close observations of Uranus. Using radio signals from the planet's auroras and magnetic field data collected by the spacecraft, astronomers at the time concluded that a day on Uranus is about 17 hours, 14 minutes, and 24 seconds long.
This rotation period was used to determine the coordinate system for the planet. However, the measured period had its own uncertainty of about 36 seconds, which accumulated with each day of Uranus. Over time, this uncertainty made it impossible to accurately determine the orientation of the planet's magnetic axis.
To get more accurate estimates of the planet's rotation period, the authors of the new study tracked the motion of auroras at Uranus' magnetic poles using six sets of Hubble observations taken between 2011 and 2022. This allowed them to refine the locations of the magnetic poles, leading to a more accurate estimate of Uranus' rotation period. The team says the new estimate has an uncertainty of less than 0.04 seconds.
“The continuous observations from Hubble were critical,” said study lead author Laurent Lamy, an astronomer at the Paris Observatory, in a statement. “Without this amount of data, it would not have been possible to detect the periodic signal with the precision we achieved.”
The 28-second difference is within the margin of error of Voyager 2's estimate, but the new duration has much less uncertainty. “It hasn't changed significantly,” Tim Bedding, an astronomer at the University of Sydney in Australia, told New Scientist. “It's now accurate enough to be more useful.”
The team reported that due to the reduced uncertainty, the coordinate system based on the new measurement of Uranus's rotation period should remain valid for several decades. Future missions to Uranus, such as the planned Uranus Orbiter and Probe, could use this coordinate system to select entry points, the researchers wrote in their study.
“Thanks to this new longitude system, we can now compare auroral data collected over almost 40 years and even plan the upcoming mission to Uranus,” Lamy concluded in a statement.
TOPICS Hubble Space Telescope
Skyler WareNavigate Social LinksLive Science Contributor
Skyler Ware is a freelance science journalist covering chemistry, biology, paleontology, and earth sciences. She was a 2023 AAAS Mass Media Science and Engineering Fellow at Science News. Her work has also appeared in Science News Explores, ZME Science, and Chembites, among others. Skyler holds a PhD in chemistry from Caltech.
You must verify your public display name before commenting.
Sourse: www.livescience.com
