A Mysterious Glow Warms Rings of Uranus

A composite image of the atmosphere and rings of Uranus seen in thermal emission. (Image: © UC Berkeley image by Edward Molter and Imke de Pater)
Some sort of a heat wave warms the rings of Uranus, even though the planet orbits far away from the sun.

By Elizabeth Howell | SPACE.com

New heat images of the planet, obtained by two telescopes in Chile, reveal the temperature of the rings for the first time: minus 320 degrees Fahrenheit (minus 195 degrees Celsius), or the boiling temperature of liquid nitrogen.

While that sounds cold by Earthly standards, consider that most of space is much colder, approaching a temperature at which atoms stop moving. This point is called absolute zero, which is roughly minus 460 F (minus 273 C).

And Uranus itself is located pretty far out in the solar system, where the planet receives only a fraction of the heat from the sun that the Earth receives. The ice giant orbits our star at an average distance of 19 astronomical units (AU), with each AU equivalent to the average distance from the Earth to the sun, or 93 million miles (150 million kilometers).

The scientists who captured the new images said they aren’t sure what’s causing the relative warmth. But the weird temperature proves that the brightest and densest ring at Uranus (also known as the epsilon ring) is very different from other ring systems in our solar system.

read more