Image Courtesy of NASA/JPL-Caltech.
Joel Kontinen
How long does a day last on Uranus? It seems that it
is longer than on Earth, The gas planets shield Earth From space rubble, just
as God promised to safeguard the only planet with life.
A day on Uranus just got slightly longer, thanks to
more accurate measurements of its rotation period that should help scientists
plan missions to probe the gas giant.
Figuring out the rotation period of the solar system’s
giant planets is much harder than for the likes of Mars and Earth because
ferocious wind storms make direct measurements impossible.
The first measurement of Uranus’s rotation came from
the Voyager 2 probe, which made its closest approach on 24 January 1986.
Researchers at the time determined that the planet’s magnetic field was offset
by 59 degrees from celestial north, while its rotation axis was 98 degrees
offset.
These extreme offsets mean that Uranus effectively
rotates “lying down” compared with Earth, while its magnetic poles trace a
large circle as the planet rotates. By measuring both the planet’s magnetic
field and radio emissions from aurora at its magnetic poles, researchers at the
time found that Uranus was completing a full rotation every 17 hours, 14
minutes, 24 seconds, with a margin of error of plus or minus 36 seconds.
Now, Laurent Lamy at
the Paris Observatory in France and his colleagues have measured it to be 28
seconds longer. More importantly, their measurement is 1000 times more
accurate, reducing the margin of error to a fraction of a second.
The researchers looked at images of Uranus’s
ultraviolet aurora, taken between 2011 and 2022 by the Hubble Space Telescope,
to track the long-term evolution of the planet’s magnetic poles as they circle
the axis of rotation
Tim
Bedding at the University of Sydney in Australia calls the team’s
measurement technique “very clever”, but points out that the new duration of a
day on Uranus isn’t that much different,
being within the margin of error of the old calculation. “It’s not so much that
it’s changed,” B edding says. “It’s now accurate enough to be more useful.”
Source:
James Woodford 2025