Astronomers Discover Planet Has Been Hiding 350,0000-Mile-Long Tail

Astronomers have discovered that a gigantic planet has been hiding a 350,0000-mile-long tail as its atmosphere seeps away.

The exoplanet known as WASP-69 is gargantuan—roughly the size of Jupiter, the largest planet in our solar system—and is about 160 light-years from Earth. It is sometimes dubbed “hot Jupiter” because the gas planet orbits incredibly close to its host star. It is so close, in fact, that it completes its orbit of the star in less than four days, by Earth’s time frame. The closest planet to our sun, Mercury, completes its orbit in 88 days.

A new study published in the Astrophysical Journal found that its star is so boiling hot atmosphere is escaping into space, at a rate of 200,000 tons per second.

The surrounding stellar winds have turned the escaping atmosphere into a tail that stretches on for at least 350,000 miles. The tail consists mainly of hydrogen and helium, and flows in the direction of Earth

“Work by previous groups showed that this planet was losing some of its atmosphere and suggested a subtle tail or perhaps none at all,” Dakotah Tyler, a UCLA doctoral student and first author of the study, said in a summary of the findings. “However, we have now definitively detected this tail and shown it to be at least seven times longer than the planet itself.”

The star has such high radiation that it is stripping away the exoplanet’s atmosphere. The atmosphere is then being funneled into its long tail. This finding helps astrophysicists learn how stellar winds are affected in planets that are uniquely close to their stars.

Findings like this also help them understand how all planets, not just WASP-69, evolve and grow with their host stars.

“Over the last decade, we have learned that the majority of stars host a planet that orbits them closer than Mercury orbits our sun and that the erosion of their atmospheres plays a key role in explaining the types of planets we see today,” co-author and UCLA professor of physics and astronomy Erik Petigura said in the summary. “However, for most known exoplanets, we suspect that the period of atmospheric loss concluded long ago. The WASP-69b system is a gem because we have a rare opportunity to study atmospheric mass-loss in real time and understand the critical physics that shape thousands of other planets.”

WASP-69b was first discovered around a decade ago. Previous observations showed barely any evidence of the tail, however astrophysicists suspected it was there.

However, this study used a much larger telescope at the W. M. Keck Observatory in Hawaii. This longer telescope gave scientists an insight they had never observed before.

“These comet-like tails are really valuable because they form when the escaping atmosphere of the planet rams into the stellar wind, which causes the gas to be swept back,” Petigura said. “Observing such an extended tail allows us to study these interactions in great detail.”

Despite the fact that its atmosphere is being sucked away by the star, the researchers said it won’t disappear completely.

“At around 90 times the mass of Earth, WASP-69b has such a large reservoir of material that even losing this enormous amount of mass won’t affect it much over the course of its life. It’s in no danger of losing its entire atmosphere within the star’s lifetime,” Tyler said.

“The resilience of this planet in such an extreme and hostile environment serves as a powerful reminder to us all,” he added. “Despite the multitude of challenges we may face, our capacity to withstand and overcome is often far greater than we realize. Our problems may seem daunting, but like WASP-69b, we have what it takes to continue on.”

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