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NASA's Kepler Space Telescope Discovers Wobbling Planet

Representation of the Kepler-413b System. The blue line is the planet's orbit.
Representation of the Kepler-413b System. The blue line is the planet's orbit.
Photo: NASA, ESA, and A. Feild (STScI)

NASA's Kepler Space Telescope has discovered a planet that wobbles wildly on its axis, much like a spinning top on the verge of falling down. The planet, designated Kepler-413b because astronomers are terrible at coming up with catchy names, is located 2,300 light-years away from Earth, orbiting a binary star system in the constellation Cygnus.

Our planet too is a bit wobbly. Very slowly, over the course of thousands of years, the Earth's axis tilts. Astronomers call this phenomenon precession. The Earth's precession is caused by the gravitational forces of the sun and moon. Its axis changes up to 23.5 degrees over a period of 26,000 years. This causes consistent changes in our climate as different parts of the planet are tilted slightly toward or away from the sun.

Kepler-413b, however, precesses at a much faster rate. Its axis can vary by up to 30 degrees in just 11 years, causing erratic climate change as it follows an equally wobbly orbit around its suns. The planet's orbit is out of alignment in relation to the orbit of the binary star system, moving up and down over time as a result of Kepler-413b's wobbly axis. This led to some confusion for astronomers using the Kepler telescope.

The Kepler Space Telescope discovers planets when they transit in front of their stars, making tiny but visible changes in the light that reaches us here on Earth. At first, astronomers saw Kepler-413b transit three times over a period of six months. Then, due to its strange orbit, there was nothing for over two years. Suddenly, the planet reappeared again, transiting another five times, once every 66 days. The planet is not expected to cross in front of its star again until 2020.

Astronomers are still theorizing about why Kepler-413b is out of alignment with its stars. There may be other large objects in the system whose gravitation pull interferes with the orbit, such as other planets or large asteroids. Another possibility is that a third star, which appears close to the binary stars, is actually much nearer than anticipated, and exerts a gravitational pull on Kepler-413b from outside the system.

Unfortunately, even aside from its wildly changing climate, Kepler-413b is far out of range of being habitable. it's a gas giant like Neptune, with no rocky surface to walk on, and it's far too hot to have liquid water. Although the Kepler telescope will continue searching for other planets, I'm betting it will swing back around come 2020, when the wobbling oddity comes into view once again.