For centuries, the solar system was viewed as a standard blueprint for planetary systems in the universe, with a star (our sun) at the center of a circular track, and a planet orbiting within each lane. Smaller, rockier planets fill the interior lanes, and larger gas giants orbit further out.

But over the last 20 years, more powerful telescopes have revealed, far from our solar system, a host of exotic systems with completely unexpected configurations. “Hot Jupiters,” for example, are massive “roaster” planets that circle scorchingly close to their stars. Scientists have puzzled over how these gas giants, which supposedly form far from their stars, end up on such blistering orbits.

Now an even weirder planetary system may render the puzzle more challenging. Using NASA’s Spitzer Space Telescope, scientists from MIT, the Space Telescope Science Institute, the University of California at Santa Cruz, and elsewhere have observed an exoplanet by the name of HD 80606 b. This planet is about the size of Jupiter, though four times as massive, and resides in a system 190 light years from Earth, in the constellation Ursa Major.

What makes HD 80606 b stand out amid the hundreds of exoplanets discovered recently is its highly eccentric orbit. Instead of maintaining a circular path, HD 80606 b spends about 100 days of its year traveling an oblong route away from and then returning toward its star, much like the trajectory of a comet. Then, in a matter of just 20 hours, it sweeps around the star, very nearly touching it, before swinging away again. At its closest approach, the planet receives an enormous amount of energy from its star — over a thousand times the energy the Earth receives from the sun each day.

“If the Earth were to be moved that close to our sun, it would lose its atmosphere and turn its surface to magma,” says Julien de Wit, a postdoc in MIT’s Department of Earth, Atmospheric and Planetary Sciences.

In a paper published today in Astrophysical Journal Letters, de Wit and his colleagues report on observations of HD 80606 b over 85 hours, during its closest approach to its star. The researchers have studied how the planet’s temperature changes as it approaches, sweeps by, and moves away from its star. They determined that while the star-facing side of the planet boils up to an extreme 1,400 kelvins (roughly 2,000 degrees Fahrenheit) during the swingby, these roasting temperatures are short-lived. Surprisingly, they found that the planet cools in fewer than 10 hours as it orbits away, reaching temperatures so cold that it becomes invisible to Spitzer for the rest of its orbit.

“This happens every 111 days,” de Wit says. “The good thing is, the planet goes so far away that the process is a complete reset. It’s the same story over and over again.”