Hubble discovers two new satellites of Pluto

[neutrino]

NASA'S HUBBLE REVEALS POSSIBLE NEW MOONS AROUND PLUTO

Using NASA's Hubble Space Telescope to view the ninth planet in our solar system, astronomers discovered Pluto may have not one, but three moons.

If confirmed, the discovery of the two new moons could offer insights into the nature and evolution of the Pluto system; Kuiper Belt Objects with satellite systems; and the early Kuiper Belt. The Kuiper Belt is a vast region of icy, rocky bodies beyond Neptune's orbit.

http://hubblesite.org/newscenter/newsdesk/archive/releases/2005/19/text/

http://www.space.com/scienceastronomy/051031_pluto_moons.html

 

[vincentm]

Has an atmosphere even been detected yet on Pluto, other than methane?

 

[neutrino]

Has an atmosphere even been detected yet on Pluto, other than methane?

A quote from http://www.nineplanets.org/pluto.html"

"Little is known about Pluto's atmosphere, but it probably consists primarily of nitrogen with some carbon monoxide and methane. It is extremely tenuous, the surface pressure being only a few microbars. Pluto's atmosphere may exist as a gas only when Pluto is near its perihelion; for the majority of Pluto's long year, the atmospheric gases are frozen into ice. Near perihelion, it is likely that some of the atmosphere escapes to space perhaps even interacting with Charon. NASA mission planners want to arrive at Pluto while the atmosphere is still unfrozen."

 

[Orion1]

Astronomers using the Hubble Space Telescope glimpsed the two new satellites back in May, and were intrigued when the pair of possible moons appeared to move around Pluto over three days in what looked like a nearly circular orbit.

the new satellites are called simply P1 and P2.

The newfound putative satellites are likely much smaller than Charon, ranging in size from perhaps 30 miles to 100 miles in diameter. Scientists are still trying to figure this out.

many scientists consider Pluto and Charon to be a binary system, with the moon orbiting about 12,000 miles from the planet.

Charon is about 745 miles across, and Pluto is about 1,430 miles across.

Reference:
http://i.a.cnn.net/cnn/2005/TECH/space/10/31/pluto.moons.reut/vert.pluto.moons.jpg
http://www.cnn.com/2005/TECH/space/10/31/pluto.moons.reut/index.html

 

[Danger]

Oh great. Two more moons around something that might not even be a planet. If Pluto happens to end up categorized as 'not a planet', what would the satellites around it be considered? (Or has the planet/not a planet issue been firmly resolved?)

 

[SpaceTiger]

Oh great. Two more moons around something that might not even be a planet. If Pluto happens to end up categorized as 'not a planet', what would the satellites around it be considered?

Satellites of a Kuiper Belt object, I would imagine. There are non-planetary objects in the solar system that have one or more satellites. For example, the asteroid Ida has a moon called Dactyl.

(Or has the planet/not a planet issue been firmly resolved?)

I don't think it has. I suspect you'll see Pluto demoted eventually.

 

[Danger]

Thanks, Tiger. I hadn't heard of Ida/Dactyl before. I guess it just never crossed my mind that a non-planetary body would have enough gravity to maintain a satellite. Now for something even weirder that just popped into my head while I was typing that:
Would it be possible for a large moon such as Titan to have a satellite of its own, sort of like a scaled down version of the sun/Earth/moon system? I know that it can be done artificially, such as the Apollo lunar orbiter, but could it form that way naturally given the overpowering gravity of the host planet?

 

[Astronuc]

Update -

New 'Planet' Is Bigger Than Pluto
By ALICIA CHANG, AP

[size=8pt]LOS ANGELES (Feb. 1) - Scientists say they have confirmed that a so-called 10th planet discovered last year is bigger than Pluto, but that likely won't quell the debate over what makes a planet.

The astronomers who spotted the icy, rocky body - informally called UB313 - had reported only a rough estimate of its size based on its brightness.

But another group of researchers has come up with what is believed to be the first calculation of UB313's diameter - 1,864 miles.

By measuring how much heat it radiates, German scientists led by Frank Bertoldi of the University of Bonn estimated that UB313 was about 1,864 miles across. That makes it larger than Pluto, which has a diameter of about 1,429 miles.

"It is now increasingly hard to justify calling Pluto a planet if UB313 is not also given this status," Bertoldi said in a statement.

Details were published in Thursday's issue of the journal Nature.[/size]

Apparently this month, scientists will use Hubble Space Telescope (HST) to make additional measurements of Pluto and its 'partners'. The objective is to add data to what has already been collected in order to confirm that there are indeed other small bodies out there.

From www.Stardate.org, February 1, 2006

Since its discovery in 1930, Pluto has remained an aloof little world. It's so small and far away that it appears as nothing more than a dot in even the largest telescopes. It has a moon that's about half as big as Pluto, but it wasn't discovered until 1978. And it may have a couple of more moons that were discovered just last year. Astronomers will hunt for those moons with Hubble Space Telescope this month.

Hubble detected the possible moons in a series of pictures it snapped three days apart back in May. The images showed a couple of tiny points of light near the planet. It's unlikely that they're stars or other background objects. But the team of astronomers that made the observations wants to check one more time. If the objects are still there, astronomers will confirm that Pluto has three moons, not one.

Pluto is a member of the Kuiper Belt -- a broad ring of icy bodies that orbits the Sun outside the orbit of the planet Neptune. Pluto was the first member of the belt ever discovered. But in recent years, astronomers have discovered hundreds of Kuiper Belt objects -- including some that are close to the same size as Pluto.

These discoveries have created some chaos in how astronomers classify planets. Some want to take Pluto off the list of planets, while others want to add the biggest of the newly found Kuiper Belt objects. Pluto's new moons will add to the debate, as astronomers ponder what to do with this aloof little world.

 

[|Orion's Thought|]

Is it possible that Pluto is an escaped moon of Neptune, and its odd plane of orbit is due to an unseen celestial body such as a brown dwarf?

 

[tony873004]

...I guess it just never crossed my mind that a non-planetary body would have enough gravity to maintain a satellite...

...Would it be possible for a large moon such as Titan to have a satellite of its own...

The Hill Sphere is how you would determine that. Here's a calculator for you: http://orbitsimulator.com/cmc/HillSphere.html . Keep your units in meters and kilograms.

I believe in the Apollo missions, the discarded waste bags orbited the command module. (or maybe I bought into the myth).

Titan... possible, yes. There's certainly room for a stable satellite in its Hill Sphere. But whether or not the Hill Sphere of Titan has been stable over its history as it migrated to its current position may make it unlikely.

To date we know of no natural objects that orbit an object that orbit an object that orbits the Sun.
Sorry for responding to a November post

Is it possible that Pluto is an escaped moon of Neptune, and its odd plane of orbit is due to an unseen celestial body such as a brown dwarf?

Possible? Sure. Probable, no. For starters, it has moons. Read my reply to Danger. You'd also have to wonder how it escaped Neptune and then got locked into a resonance with it.

 

[|Orion's Thought|]

Possible? Sure. Probable, no. For starters, it has moons.

I recently saw a program about Pluto and the New Horizons spacecraft , and it said that Pluto and Charon orbit around an axis (not inside pluto, but closer to it than charon), so I was wondering if it was possible that pluto's and charon's gravity wells connected to from the orbiting thingy (i forget the name) where they both orbit around a singular axis

 

[tony873004]

They orbit their common barycenter, as do all objects. Earth and the Moon have a common barycenter which is below the Earth's surface. Pluto & Charon's common barycenter is unique among planets because it is above the surface of Pluto. Several asteroids share this trait, as does the Sun and Jupiter. Thanks to Jupiter, the solar system barycenter is slightly outside the Sun's photosphere, in its corona.

Here's an animated GIF of the Pluto and Charon orbiting their common barycenter. Pluto is purple, Charon is white:

http://orbitsimulator.com/gravity/PlutoCharon.GIF

 

[plusaf]

They orbit their common barycenter, as do all objects. Earth and the Moon have a common barycenter which is below the Earth's surface. Pluto & Charon's common barycenter is unique among planets because it is above the surface of Pluto. Several asteroids share this trait, as does the Sun and Jupiter. Thanks to Jupiter, the solar system barycenter is slightly outside the Sun's photosphere, in its corona.

Here's an animated GIF of the Pluto and Charon orbiting their common barycenter. Pluto is purple, Charon is white:

http://orbitsimulator.com/gravity/PlutoCharon.GIF

and that wobble is the way the first exosolar planets were discovered.
right?
+af