New Exoplanet Shouldn't Exist

A report in the journal Nature cites the discovery of a new planet, WASP-18b, which challenges assumptions about tidal interactions--it's too close and orbiting too fast not to have collided with its star, according to current knowledge. Cynthia Graber reports

Illustration of a Bohr atom model spinning around the words Science Quickly with various science and medicine related icons around the text

Join Our Community of Science Lovers!

[The following is an exact transcript of this podcast.]

A planet has been discovered about 325 light-years away. But what’s really interesting is that it shouldn’t exist. The planet is called WASP-18b, because it was observed by a project called WASP, the Wide Area Search for Planets. It has 10 times the mass of Jupiter, and orbits its star in less than one earth day. Because it’s crazy close to its star, only 1.4 million miles. We’re 93 million miles from the sun.

Tidal interactions should have stretched the star and slowed the planet to the point where they smashed into each other a long time ago. The research is in the August 27th issue of the journal Nature. [Scientific American is part of the Nature Publishing Group.]


On supporting science journalism

If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.


WASP-18b is part of a class of planets called “hot Jupiters,” which are thought to have formed a great distance from their home stars and then migrated inward.

Researchers say this particular planet has been around for about a billion years. We may have caught it in its death throes. Or, there are unknown factors keeping the star and planet from colliding. So astrophysicists intend to keep a close eye on WASP-18b, to either catch the orbit decaying or figure out why it isn’t.

—Cynthia Graber

It’s Time to Stand Up for Science

If you enjoyed this article, I’d like to ask for your support. Scientific American has served as an advocate for science and industry for 180 years, and right now may be the most critical moment in that two-century history.

I’ve been a Scientific American subscriber since I was 12 years old, and it helped shape the way I look at the world. SciAm always educates and delights me, and inspires a sense of awe for our vast, beautiful universe. I hope it does that for you, too.

If you subscribe to Scientific American, you help ensure that our coverage is centered on meaningful research and discovery; that we have the resources to report on the decisions that threaten labs across the U.S.; and that we support both budding and working scientists at a time when the value of science itself too often goes unrecognized.

In return, you get essential news, captivating podcasts, brilliant infographics, can't-miss newsletters, must-watch videos, challenging games, and the science world's best writing and reporting. You can even gift someone a subscription.

There has never been a more important time for us to stand up and show why science matters. I hope you’ll support us in that mission.

Thank you,

David M. Ewalt, Editor in Chief, Scientific American

Subscribe