Shortest Year

StarDate: March 13, 2011

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If you're impatient to celebrate your next birthday, you might want to move to a planet in the constellation Cancer. A year there lasts less than a day here on Earth.

Here on Earth, you have to wait 365 days between birthdays -- 366 in leap years -- because Earth takes 365 and a quarter days to orbit the Sun.

Planets closer to the Sun have shorter years, because their orbits are smaller and they move faster. Mercury, the innermost planet in the solar system, completes an orbit every 88 days. So any Mercurians would enjoy four birthdays in the same time we Earthlings get just one.

If you'd really like to stock up on the birthday presents, though, head to the star 55 Cancri. It's 40 light-years away in the constellation Cancer, the crab. The star is faintly visible to the unaided eye, although you need help to find it.

55 Cancri is similar to the Sun, and it has five known planets. The innermost is a so-called "super Earth," which means it's only a few times heavier than our world -- one of the lightest-weight planets yet discovered.

One other thing that makes the planet special is its ultra-short year. The planet orbits 55 Cancri once every 17 hours and 41 minutes. It's the shortest year of any confirmed planet -- making 55 Cancri the perfect place if you love birthday parties.

There's just one tiny problem. Because the planet is so close to its sun, its surface temperature must be thousands of degrees. So be sure to specify that all those birthday presents be fireproof.

Script by Ken Croswell, Copyright 2011

For more skywatching tips, astronomy news, and much more, read StarDate magazine.

The one constant in the Universe: StarDate magazine

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