How long does a day last on Uranus? Slightly longer than we thought, it seems

A day on Uranus was slightly longer, thanks to more precise measures of its rotation period which should help scientists plan missions to probe the gas giant.

The determination of the period of rotation of the giant planets of the solar system is much more difficult than for Mars and Earth, because the storms of ferocious wind make the direct measures impossible.

The first measurement of the rotation of Uranus came from the Voyager 2 probe, which made its closest approach on January 24, 1986. The researchers at the time determined that the magnetic field of the planet was offset of 59 degrees of the North Celeste, while its axis of rotation was compensated at 98 degrees.

These extreme shifts mean that Uranus effectively turns “lying down” compared to the earth, while its magnetic poles trace a large circle when the planet turns. By measuring both the magnetic field and the radio emissions from the planet of Aurora to its magnetic poles, the researchers at the time revealed that Uranus finished a complete rotation every 17 hours, 14 minutes, 24 seconds, with a margin of error more or less 36 seconds.

NOW, Laurent Lamy At the Paris Observatory in France and his colleagues measured it at 28 seconds more. More importantly, their measurement is 1000 times more precise, reducing the margin of error to a fraction of a second.

The researchers examined the images of the ultraviolet Aurora d'Uranus, taken between 2011 and 2022 by the Hubble space telescope, to follow the long -term evolution of the planet's magnetic posts while surrounding the rotation axis.

The margin of error of the previous measure allowed that it has become impossible to precisely determine a position on Uranus more than a few years later, but the new measure should remain valid for decades. This means that it could be invoked to calculate critical mission objectives such as when a probe could orbit and enter the planet's atmosphere.

Tim bedding At the University of Sydney in Australia, calls the “very intelligent” team measurement, but stresses that the new duration of a day on Uranus is not so different, being in the margin of error of the old calculation. “It's not that much has changed,” said Bedding. “It is now precise enough to be more useful.”