More Moons Around Pluto? Options

[JRehling]

Press Release Source: NASA


NASA's Hubble Reveals Possible New Moons Around Pluto
Monday October 31, 12:30 pm ET


WASHINGTON, Oct. 31 /PRNewswire/ -- 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.

"If, as our new Hubble images indicate, Pluto has not one, but two or three moons, it will become the first body in the Kuiper Belt known to have more than one satellite," said Hal Weaver of the Johns Hopkins Applied Physics Laboratory, Laurel, Md. He is co-leader of the team that made the discovery.

Pluto was discovered in 1930. Charon, Pluto's only confirmed moon, was discovered by ground-based observers in 1978. The planet resides about 3 billion miles from the sun in the heart of the Kuiper Belt.

"Our result suggests other bodies in the Kuiper Belt may have more than one moon. It also means planetary scientists will have to take these new moons into account when modeling the formation of the Pluto system," said Alan Stern of the Southwest Research Institute, Boulder, Colo. Stern was co-leader of the research team.

The candidate moons, provisionally designated S/2005 P1 and S/2005 P2, were observed approximately 27,000 miles away from Pluto. The objects are roughly two to three times as far from Pluto as Charon.

The team plans to make follow-up Hubble observations in February to confirm the newly discovered objects are truly Pluto's moons. Only after confirmation will the International Astronomical Union consider names for S/2005 P1 and S/2005 P2.

The Hubble's Advanced Camera for Surveys observed the two new candidate moons on May 15, 2005. The candidates are roughly 5,000 times fainter than Pluto. Three days later, Hubble looked at Pluto again. The two objects were still there and appeared to be moving in orbit around Pluto.

The team looked long and hard for other potential moons around Pluto. "These Hubble images represent the most sensitive search yet for objects around Pluto," said team member Andrew Steffl of the Southwest Research Institute. "It is unlikely that there are any other moons larger than about 10 miles across in the Pluto system," he said.

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. The Space Telescope Science Institute in Baltimore conducts Hubble science operations. The Institute is operated for NASA by the Association of Universities for Research in Astronomy, Inc., Washington.


For detailed information and images about this research on the Web, visit:

http://hubblesite.org/news/2005/19

For information about NASA and agency programs on the Web, visit:

http://www.nasa.gov/home




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Source: NASA

[Gsnorgathon]

All this talk of resonance and opposition surges makes me wonder - are the masses of the two moons enough to result in any geological activity on any of the four bodies in the Pluto system?

I'm also wondering - I know the new moons were imaged in 2002; is there any chance that they show up in any of the data from the 1985 - 1990 Pluto/Charon mutual occulatations? My first guess is they'd be buried in the noise, but hope springs eternal.

[tasp]

All this talk of resonance and opposition surges makes me wonder - are the masses of the two moons enough to result in any geological activity on any of the four bodies in the Pluto system?

I'm also wondering - I know the new moons were imaged in 2002; is there any chance that they show up in any of the data from the 1985 - 1990 Pluto/Charon mutual occulatations? My first guess is they'd be buried in the noise, but hope springs eternal.

Yes, excellent point, the mutual occultation data may show something IF the observations, sync-ed to Charon, happened to sync up with the 2 'outies'.

Now, how everything was 'phased' out in that time period is a big???

Any data though would reveal diameter and oblateness, help pin down i and e, and perhaps mutual perturbations (if they occur in resonant relationships, if they are resonant) that might help derive masses for the two little guys. If you get diameter, you can figure albedo too. Color data during a mutual event would be great for narrowing down surface composition.

I believe data was taken as Pluto eclipsed Charon, and vice versa. How much data was recorded in between, I dunno.

Stellar occultation data from that time may show something too, if we get lucky, and the more data to go through, the better the chances get.

[Rob Pinnegar]

Yes, excellent point, the mutual occultation data may show something IF the observations, sync-ed to Charon, happened to sync up with the 2 'outies'...

Ummm... I could be wrong about this, but doesn't that occultation data consist of measurements of the Pluto-Charon system's apparent magnitude, rather than images?

[tasp]

Ummm... I could be wrong about this, but doesn't that occultation data consist of measurements of the Pluto-Charon system's apparent magnitude, rather than images?

Yes, and if one of the two new guys pops into or out of either Pluto or Charon's shadow, or if either transits Pluto or Charon, the brightness of the whole system changes.

Amazing if we have such data on hand waiting to be analyzed.

[tasp]

Yes, and if one of the two new guys pops into or out of  either Pluto or Charon's shadow, or if either transits Pluto or Charon, the brightness of the whole system changes.

Amazing if we have such data on hand waiting to be analyzed.

Left out something:

It may be possible for either or both new objects to cast a shadow on Pluto or Charon, at various times during the Plutonian year. An observer on Pluto in the shadow would be experiencing a total solar eclipse. (I worked this out in my head, think both satellites should be large enough to eclipse sun). From earth's vantage point, the object casting the shadow upon Pluto (or Charon) would not necessarily simultaneously transit the disk of Pluto (or Charon).

But at some point it could. (I'm getting dizzy watching this happen in my head, yoiks)

[Rob Pinnegar]

It may be possible for either or both new objects to cast a shadow on Pluto or Charon, at various times during the Plutonian year.

Yup... and if their orbits are coplanar with Charon's, the next set of eclipses of this type should start in about a hundred and ten years.

[ljk4-1]

Yup... and if their orbits are coplanar with Charon's, the next set of eclipses of this type should start in about a hundred and ten years.

Has anyone gone back in the astronomical records to see if Pluto's two "new" moons were imaged before this year?

I know that was the case with Charon going back to 1965 at least and for Pluto going back to 1915 or so.

While I am wondering, if there are other KBOs out there bigger than Pluto, and assuming they are not ridiculously far away, how did they escape detection before 1992? Or do some of them also exist on older astrophotos hidden away in some dusty file cabinet of some university observatory?

[David]

Has anyone gone back in the astronomical records to see if Pluto's two "new" moons were imaged before this year?

I know that was the case with Charon going back to 1965 at least and for Pluto going back to 1915 or so.

This sort of thing is apparently the rule for "newly-discovered" bodies, rather than the exception. Uranus, discovered in 1781 by Herschel, was first recorded in 1690 by Flamsteed. Neptune, discovered in 1846 by Galle, was first sighted as early as 1613 by Galileo! I don't know if Ceres appears on any astronomical charts before 1801, but I wouldn't be surprised.