The 'exotic' super-Earth that's as dense as lead

Astronomers have spotted an "exotic" planet — a nearby "super-Earth" — that they say is the most solid planet ever discovered, with a density very similar to lead. Here, a guide to this find:

What is a "super-Earth"?

A super-Earth is a planet outside our solar system with a mass higher than Earth's, but lower than our own solar system's large gas planets.

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And what is this particular super-Earth?

It's called 55 Cancri e, and is about 40 light years away from Earth. The planet is 13,000 miles in diameter, or 60 percent larger than Earth, but it is eight times as massive. A year on 55 Cancri e lasts just 18 hours, and its sun is bright enough to be seen from Earth without a telescope.

How did scientists spot it?

Since 1997, astronomers had discovered five planets orbiting the star 55 Cancri (the planet 55 Cancri e takes its name from the star it orbits). Last year, two researchers re-analyzed data about 55 Cancri e and concluded that it might revolve around the star faster than originally thought. So they joined up with other scientists and used Canada's MOST space telescope to get more information about the planet.

Do scientists hope to find alien life on 55 Cancri e?

No. The temperature on the surface of the planet could be as high as 4,900 degrees Fahrenheit. "Because of the infernal heat, it's unlikely that 55 Cancri e has an atmosphere," says MIT scientist Josh Winn, as quoted by Space.com. "So this is not the type of place where exobiologists would look for life."

So why is this planet important?

It "could be the most significant breakthrough yet in the study of planet evolution and survival," says the Daily Mail. The brightness of the star 55 Cancri allows incredibly precise and detailed measurements, which makes this super-Earth "the perfect laboratory to test theories of planet formation, evolution and survival," says Winn.

Sources: Daily Mail, International Business Times, Space.com, Space Daily, Vancouver Sun, UPI