Pluto Has New Moon
EmailJust seeing it was an accomplishment. The Hubble Space Telescope has spotted a tiny new moon, somewhere between 8 and 21 miles in diameter, in orbit around Pluto.
Pluto was already known to have three other moons, named Charon, Nix and Hydra; this newest one is, for now, designated P4.
(Hubble's June 28 image. Click on it to enlarge.)
"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 the observing program with Hubble. NASA's New Horizons spacecraft is set to fly past Pluto in July 2015, and mission organizers want to know before then just what they should look for.
P4 first showed up in an image shot by the Hubble on June 28. Its presence was confirmed by follow-up pictures shot on July 2 and July 18, says the Space Telescope Science Institute. It may, in fact, have shown up in a long-exposure image in 2006, but until now, nobody was really watching Pluto's environs for anything that reflected so little light.
What might it be like on P4? Dark and cold, for sure, but beyond that it's dangerous to guess. It's too small to have much graviational pull, almost undoubtedly too small for its gravity to have pulled it into a spherical shape. But does it have ice or rock, a shiny surface or a dark one? Now begin the calculations so that New Horizons, as it races through the Pluto-Charon system, can shoot images of P4 on the way.
Obviously, it needs a more evocative name. Pluto and its other moons have, by tradition, been named for mythological figures from the underworld. P4's discoverers get the honor of picking a permanent name for their find; they may welcome ideas.
Solar Eclipse Seen Only by Satellite 
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You have to wonder what else is out there…Heaven eventually? There are many mysteries. Centuries ago they thought the world was flat. Makes you wonder what will be centuries from now. Amazing!
Posted by: Barb | July 20, 2011, 1:08 pm 1:08 pm
Seems Pluto should be promoted back to full planet status if it itself has moons. I always like reading your articles Ned.
Posted by: pgd | July 20, 2011, 1:38 pm 1:38 pm
Cool!!
Posted by: Jim | July 20, 2011, 2:02 pm 2:02 pm
Good article. Nice to actually learn something while reading the news.
Posted by: Joe Don | July 20, 2011, 2:03 pm 2:03 pm
I agree. I don’t think Pluto should have ever been taken off the list of planets. Let’s put it back on.
Posted by: Bill | July 20, 2011, 2:18 pm 2:18 pm
Guys, Pluto his a highly irregular orbit, off in spacing, extra-elliptical nature, and even the plane on which it lies. Not to mention Charon is half as big as Pluto, almost making it a binary planet.
Too weird to be a normal planet.
Also keep in mind if we made Pluto a “full planet” then we’d have to include Sedna as well…
We’re never going back to MVEMJSUNP, period. Because science moves forward.
Personally, I love it.
Posted by: Alan | July 20, 2011, 2:26 pm 2:26 pm
Pluto isn’t anything like a typical planet, but what we call it is really irrelevant. It is still Pluto.
Posted by: jock59801 | July 20, 2011, 2:50 pm 2:50 pm
The universe is only about 6000 years old. The Bible says so. All the other “science” stuff is just opinion.
Just Kidding!
Posted by: htgriff | July 20, 2011, 3:39 pm 3:39 pm
Let me be the first to suggest the new moon be named “Yuggoth”. Go on, Google it.
Posted by: H.P. Lovecraft | July 20, 2011, 4:03 pm 4:03 pm
Posted by: Bill “We’re never going back to MVEMJSUNP, period”
No we’ll probably end up moving to a MVEMJSUNPS+, period instead at some point. I have no problem classifying Sedna as a planet. Its Roughly two-thirds the size of Pluto, so theoretically its large enough to be rounded by its own gravity, However, its distance from the Sun makes determining its shape difficult.
Also the fact that Pluto has a highly irregular orbit is no reason to disqualify it as a planet. It more than likely that we’ll find exoplanet, outside the Solar System as large as Jupiter that also have highly elliptical orbits and may not have cleared thier neighboring region of planetesimals.
Personal I think the current IAU definition of planet, should be rejects because it defines dwarf planets as something other than a type of planet, and for using orbital characteristics (rather than intrinsic characteristics) of objects to define them as dwarf planets.
Posted by: Nic1234567 | July 20, 2011, 4:27 pm 4:27 pm
pluto, sedna, etc are “planetoids”. bigger than asteroids, not quite planets. there, definition problem solved. and i favor “cerberus” as the name p4.
Posted by: tom | July 20, 2011, 5:03 pm 5:03 pm
Shhhh…don’t tell Nasa about this new moon P4…they will want to lobby congress to fund a program to send a man to it…
Posted by: RalphF | July 20, 2011, 5:17 pm 5:17 pm
I don’t like change….pluto is a planet just a small one put it back to the way it is.
Posted by: Footie Hill | July 20, 2011, 5:20 pm 5:20 pm
How about naming the new moon, Proserpina, the wife of Pluto? P=First letter. 4=four consonants in the name.
Posted by: Ted TampaBay | July 20, 2011, 5:30 pm 5:30 pm
It’s a small, small world after all.
Posted by: lets-see | July 20, 2011, 8:40 pm 8:40 pm
Pluto is not considered a planetoid. The terms asteroid, minor planet, and planetoid are more or less synonymous. They’re are distinct from planetary bodies (Pluto include) in that their self-gravity is insufficient to achieve hydrostatic equilibrium, that is, an ellipsoidal shape. Under the new IAU definition minor planet and comets are to be called “Small Solar System bodies”.
Posted by: Nic1234567 | July 21, 2011, 12:40 am 12:40 am
Pluto is not concerned with it’s status (planet, planetoid, dwarf planet, frozen rock, whatever). We have only been aware of it’s existence for 81 years, and it has only completed about a third of an orbit in that time. There are a lot of passionate people who decry it’s recent demotion, but it is unlikely to affect Pluto’s relationship with the rest of the solar system.
Posted by: Dogboy | July 21, 2011, 1:54 am 1:54 am