Uranus at Opposition

Thousands of planets have been found in other star systems. They’re all so far away, though, that most are no more than squiggly lines on a computer screen. Yet scientists are slowly teasing the details out of the squiggles.

To understand how difficult the problem is, consider that there’s still a lot to learn about the planets of our own solar system.

One mystery, for example, is why the planet Uranus radiates very little energy into space.

The four outermost planets — Jupiter, Saturn, Uranus, and Neptune — are all giants. They’re so massive that gravity tightly squeezes their insides, producing heat that radiates into space. In fact, three of the four emit a lot more energy than they receive from the Sun. The exception is Uranus, where the energy is roughly balanced — and scientists are trying to figure out why.

Another mystery is the planet’s climate. Uranus lies on its side, with each pole receiving 42 years of sunlight followed by 42 years of darkness. Astronomers are watching how the climate changes with the seasons — one of the mysteries of a world in our own neighborhood.

Uranus is passing closest to Earth about now, so it’s biggest and brightest for the year. Even so, you need binoculars to spot it — especially tonight. It’s low in the east as night falls, close to the upper right of the full Moon.

We’ll talk about the Moon and a much brighter companion tomorrow.

Script by Damond Benningfield