Arriving at Uranus in 1986, Voyager 2 observed a bluish orb with extremely subtle features. A haze layer hid most of the planet’s cloud features from view. Image: NASA/JPL-Caltech
Scientists think they’ve found two new moons orbiting Uranus, using data acquired from Voyager 2’s flyby in 1986.
As Rosetta retires with a bang, Schiaparelli crashes, Hubble awaits its replacement, Martian rovers potter about the Red Planet, and delivery ships to and fro from the International Space Station, NASA’s missions with the longest briefs – Voyager 1 and Voyager 2 – continue to amaze.
Launched in 1977, less than a fortnight apart, Voyager 1 and Voyager 2’s impact on scientific discovery continues to this day.
Voyager 1 is currently in what’s called ‘interstellar space’, some 20bn km from Earth. Voyager 2, its younger brother, is in the ‘heliosheath’. This is the outermost layer of the heliosphere where the solar wind is slowed by the pressure of interstellar gas, almost 17bn km from home.
However for Voyager 2, in a never-ending trip away from Earth, the discoveries made off the back of its research are ongoing.
An image it took of Uranus in 1986 as it neared the edge of our solar system is still offering fascinating insights into the planetary make-up of our nearest and dearest neighbours.
A new study led by University of Idaho researchers suggests there could be two tiny, previously undiscovered moonlets orbiting near two of the planet’s rings.
Uranus is seen in this false-colour view from NASA’s Hubble Space Telescope from August 2003. The brightness of the planet’s faint rings and dark moons has been enhanced for visibility. Image: Erich Karkoschka and NASA
Rob Chancia spotted key patterns in the two rings while examining Voyager 2’s images, with the material on the rings varying periodically.
“When you look at this pattern in different places around the ring, the wavelength is different – that points to something changing as you go around the ring. There’s something breaking the symmetry,” said Matt Hedman, who worked with Chancia to investigate the finding.
Their results will be published in The Astronomical Journal.
The duo think the moons may be as little as 4km in diameter, smaller than any of Uranus’ current moons, which themselves are hard to spot due to the dark material covering them.
“We haven’t seen the moons yet, but the idea is that the size of the moons needed to make these features is quite small, and they could have easily been missed,” Hedman said. “The Voyager images weren’t sensitive enough to easily see these moons.”
Next, it’s up to other scientists to investigate if Hedman and Chancia’s potential discovery is real, using telescopes and other spacecraft images.
In 1996, Hubble followed on from Voyager 2’s capture of Uranus, with this picture revealing the distant planet’s clear and hazy layers of atmosphere, which are created by a mixture of gases. Using infrared filters, Hubble captured detailed features of three layers of the planet’s atmosphere. Image: Erich Karkoschka and NASA
