Newly Discovered Strange Planet Has 3 Suns

— -- Imagine a strange new world where it's always daytime or there are triple sunrises and sunsets.

The unique daylight situation is a reality on the newly discovered exoplanet HD 131399Ab. The planet is believed to be a relatively young 16 million years old. It's about 340 light-years from Earth in the constellation Centaurus, according to NASA.

A study detailing the exoplanet was published this week in the journal Science.

Exoplanets are planets that orbit a star other than our sun.

With an orbit that takes 550 years, HD 131399Ab's seasons last longer than a human lifetime. The exoplanet orbits the largest of its three suns, and the two smaller stars form a binary system also in orbit around the largest sun.

"For much of the planet's year, the stars appear close together, giving it a familiar night side and day side, with a unique triple sunset and sunrise each day," Kevin Wagner, a doctoral student at the University of Arizona and the paper's first author, said in a statement.

For one-quarter of its orbit — about 140 Earth years — the planet is in nearly constant daylight as it passes between the three stars, Wagner said.

The new world is the first to be discovered using SPHERE, the Spectro-Polarimetric High-Contrast Exoplanet Research instrument, which is installed on the Very Large Telescope at the European Southern Observatory in Chile's Atacama Desert and is tasked with finding planets around other stars.

SPHERE's high sensitivity allows it to detect the heat signatures of young planets, according to NASA. HD 131399Ab has a temperature of 850 kelvins (about 1,070 degrees Fahrenheit) — one of the coldest known exoplanets, NASA said.