Skip to comments.Hubble Discovers a New Moon Around Pluto
Posted on 07/20/2011 3:23:56 PM PDT by MikeD
Astronomers using the Hubble Space Telescope have discovered a fourth moon orbiting the icy dwarf planet Pluto. The tiny, new satellite temporarily designated P4 -- popped up in a Hubble survey searching for rings around the dwarf planet.
The new moon is the smallest discovered around Pluto. It has an estimated diameter of 8 to 21 miles (13 to 34 km). By comparison, Charon, Pluto's largest moon, is 648 miles (1,043 km) across, and the other moons, Nix and Hydra, are in the range of 20 to 70 miles in diameter (32 to 113 km).
"I find it remarkable that Hubble's cameras enabled us to see such a tiny object so clearly from a distance of more than 3 billion miles (5 billion km)," said Mark Showalter of the SETI Institute in Mountain View, Calif., who led this observing program with Hubble.
The finding is a result of ongoing work to support NASA's New Horizons mission, scheduled to fly through the Pluto system in 2015. The mission is designed to provide new insights about worlds at the edge of our solar system. Hubble's mapping of Pluto's surface and discovery of its satellites have been invaluable to planning for New Horizons' close encounter.
"This is a fantastic discovery," said New Horizons principal investigator Alan Stern of the Southwest Research Institute in Boulder, Colo. "Now that we know there's another moon in the Pluto system, we can plan close-up observations of it during our flyby."
The new moon is located between the orbits of Nix and Hydra, which Hubble discovered in 2005. Charon was discovered in 1978 at the U.S. Naval Observatory and first resolved using Hubble in 1990 as a separate body from Pluto.
The dwarf planets entire moon system is believed to have formed by a collision between Pluto and another planet-sized body early in the history of the solar system. The smashup flung material that coalesced into the family of satellites observed around Pluto.
Lunar rocks returned to Earth from the Apollo missions led to the theory that our moon was the result of a similar collision between Earth and a Mars-sized body 4.4 billion years ago. Scientists believe material blasted off Pluto's moons by micrometeoroid impacts may form rings around the dwarf planet, but the Hubble photographs have not detected any so far.
"This surprising observation is a powerful reminder of Hubble's ability as a general purpose astronomical observatory to make astounding, unintended discoveries," said Jon Morse, astrophysics division director at NASA Headquarters in Washington.
P4 was first seen in a photo taken with Hubble's Wide Field Camera 3 on June 28. It was confirmed in subsequent Hubble pictures taken on July 3 and July 18. The moon was not seen in earlier Hubble images because the exposure times were shorter. There is a chance it appeared as a very faint smudge in 2006 images, but was overlooked because it was obscured.
For images and more information about Hubble, visit: http://www.nasa.gov/hubble
Where is New Horizons now
Most exciting thing going on in space for me at this point. The Dawn mission is cool but Pluto is the one I really want to get a look at.
3 Moons now, and there are revisionists that want to downgrade Pluto from Planet status? Shame on them!
It’s too bad the next telescope to replace Hubble is having major difficulties.
The amazing thing is we’re over halfway there! I remember before launch we were all wondering what we’d be doing in ten years at arrival. Alan made a comment about most of the team still being in their fifties at arrival. I piped up that I wouldn’t quite be 40. He shot me this devlish look and told me to pipe down...
Space based optical telescopes are fast becoming obsolete thanks to adaptive optics. Its a good thing really. Maintenance can be done after breakfast and before lunch without the hassle of hoisting someone into orbit.
I know there’s a 36 meter optical array in the works. Given the global economy its hard to say when it will come online. I have read that our first real look at an exoplanet will probably come from a ground based telescope.
I say they name it “Bluto.” The Ninth Planet was originally named after him, but lobbying efforts by Popeye and Olive Oil put the deep six to that, and the Disney Compromise was the result.
I thought Pluto was demoted to asteroid..its a planet again?
I’m for calling it Spinach. You gotta do what ya gotta do.
And what NASA doesn't want you to know is that they could have launched new replacements for Hubble on unmanned rockets for much cheaper than a servicing mission.
Even the Sumerians believed Pluto to be a planet.
Thats pretty neat considering they didnt know it existed........
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I wonder if all these ‘moons’ are actually debris from a relatively recent collision. I know that Pluto and Charon are mutually tidally locked, but I don’t know about Nix, Hydra and the new one.
Optical telescopes, maybe, but you can’t do UV on the ground, and there are a number of IR bands that are difficult on the ground. Unfortunately JWST, if it happens, is IR only.
The New Horizons team has always called Pluto a planet, and always will. It’s round, it goes around the Sun, and it has more moons. What more do you need?
The leading theory from Boulder is that the moons were formed after Pluto & Charon formed. I don’t think we know enough about the new moons to know their rotation periods. They are in different orbits from Charon, so the most they could do is always show the same face to Pluto.
Pluto is still a planet to me. To hell with them... :-)
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