Astronomers observe warm glow of Uranus’ rings

thermal image of uranus rings
Composite image of Uranus’s atmosphere and rings at radio wavelengths, taken with the ALMA array in December 2017. The image shows thermal emission, or heat, from the rings of Uranus for the first time, enabling scientists to determine their temperature: a frigid 77 Kelvin (-320 F). Dark bands in Uranus’s atmosphere at these wavelengths show the presence of molecules that absorb radio waves, in particular hydrogen sulfide gas. Bright regions like the north polar spot (yellow spot at right, because Uranus is tipped on its side) contain very few of these molecules. (Credit: UC Berkeley image by Edward Molter and Imke de Pater)

The rings of the Uranus were first discovered in late 1977. Two large telescopes in the high deserts of Chile have captured surprisingly bright heat images of the planet. The rings can be seen because they reflect a little light in the visible, or optical, and near-infrared frequency range.

The new images were taken by the Atacama Large Millimeter/submillimeter Array (ALMA) and the Very Large Telescope (VLT) for the first time. They measured the temperature of the rings to be 77 Kelvin, the boiling point of liquid nitrogen which is equivalent to 320 degrees below zero Fahrenheit. The study was published in The Astronomical Journal.

The epsilon ring is the brightest and densest ring of Uranus and differs from other known rings within the solar system especially the rings of Saturn. The rings of Saturn are mostly icy, broad as well as bright and vary in size from the size of micron dust to tens of meters as told by Imke de Pater, a UC Berkeley professor of astronomy. The Epsilon ring of Uranus contains golf ball sized and larger rocks only. The rings of Jupiter contain micron-sized particles whereas the rings of Neptune are mostly dust. Uranus has a broadsheet of dust present between the narrow main rings.

A graduate student Edward Molte said that the epsilon ring is weird because the smaller particles are not visible and that something has been sweeping them out. This step can help us to understand the composition of the rings and the source of the material of each ring.

Rings could be former asteroids captured by the gravity of a planet, remnants of moons that crashed into one another and shattered, the remains of moons torn apart when they got too close to Uranus, or debris remaining from the time of formation 4.5 billion years ago.

The rings of Uranus are different from Saturn due to lower albedo in the optical and infrared region and thus they are really dark like charcoal. The rings of Uranus are narrow when compared to Saturn’s rings, the Epsilon ring of Uranus is 20 to 100 kilometers wide however the rings of Saturn are tens of thousands of kilometers wide.

The Voyager 2 which flew by in 1986 noticed a lack of dust-sized particles for the first time but was unable to measure the temperature. A total of 13 rings can be found on Uranus with gaps of dust in between. The VLT and ALMA satellites were designed to explore the temperature structure of the atmosphere of Uranus. The upcoming James Webb Space Telescope will be able to vastly improve spectroscopy of the planet.


Please enter your comment!
Please enter your name here