A day on Uranus is longer than we thought
What's the story
A recent study using data from the Hubble Space Telescope has shown that Uranus's rotation period is longer than previously thought.
The ice giant takes 17 hours, 14 minutes, and 52 seconds to finish a full rotation, the research found.
The new finding is an increase of 28 seconds from NASA's Voyager 2 spacecraft estimate, made nearly four decades ago.
Initial estimate
Voyager 2 was foundational for mapping Uranus
In January 1986, Voyager 2 became the first spacecraft to explore Uranus and estimated the planet's rotation period to be 17 hours, 14 minutes and 24 seconds.
This estimate was based on radio signals emitted by the planet's auroras and direct measurements of its magnetic field.
These figures were instrumental in calculating coordinates on Uranus as well as mapping its surface.
Data discrepancies
Voyager 2's data led to inaccuracies in longitude estimation
However, the rotation period estimated by Voyager 2 wasn't without its share of uncertainties.
The wrong estimation led to a 180-degree error in Uranus's longitude calculation, and the orientation of its magnetic axis becoming "completely lost" within two years of the spacecraft's flyby.
As a result, coordinate systems based on this outdated rotation period quickly lost their reliability, prompting a reevaluation.
Astronomers' approach
Hubble's observations crucial for determining rotation
A team of astronomers, led by Laurent Lamy from the Paris Observatory, tracked the motion of Uranus's auroras using Hubble Space Telescope data.
The study, which spanned from 2011 to 2022, enabled researchers to accurately pinpoint the planet's magnetic poles and provide a more accurate estimate of its rotational period.
"The continuous observations from Hubble were crucial," said Lamy in a statement.
Future implications
New estimate offers reliable coordinate system for Uranus
The updated estimate of Uranus's rotation period has given the ice giant a more reliable coordinate system.
This new system is expected to stay accurate for decades until future missions can provide even more refined data.
The improved estimate might also prove useful in planning future missions to Uranus, especially in orbital tours and choosing suitable atmospheric entry sites.