July 25, 2011

New Moon Rises over Pluto

A Hubble telescope search for dust rings around Pluto turned up a previously unknown moon. John Matson reports

SUBSCRIBE TO 60-Second Space

Join Our Community of Science Lovers!

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.

Pluto may not be a full-fledged planet anymore, but it's got its share of moons. Including a tiny moon just recently spotted by astronomers. The new addition, which isn't yet named, brings the dwarf planet's number of known satellites to four. That's more than Mercury, Venus, Earth and Mars have combined.

Based on Hubble Space Telescope photographs of Pluto's newfound companion, astronomers estimate the moon to be just a few dozen kilometers in diameter. Hubble also spotted Nix and Hydra, two larger moons of Pluto, in 2005. Its largest moon, Charon, has been known since the 1970s. Pluto's entire system of moons may have emerged from a protoplanetary smashup billions of years ago.

The new moon turned up during a Hubble search for a dust ring around Pluto. Such a ring could pose a hazard to NASA's New Horizons probe, now on its way to Pluto for a flyby in 2015. So far, the search for any rings has come up empty. That's good news for fans of Pluto, who are looking forward to our first close up view. And now New Horizons will have a bit more to check out once it reaches Pluto's neighborhood.

—John Matson

[The above text is a transcript of this podcast.]

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