Great picture albiet from a vast distance. Only now stumbled on it.

One other thing, on the Keck v. Hubble point. These are probably the two best telescopes *ever*, so it seems silly to try to pit the two against each other. In fact, the specifics of the science program in question will mainly determine which telescope you want to use.

- An individual Hubble exposure will always be 1 micron). However, Keck currently cannot apply adaptive optics corrections at shorter wavelengths at all.

- Hubble cameras have pretty fat pixels. E.g., the Nix+Hydra Hubble images have the finest pixels of any Hubble imaging camera (ACS-HRC, which is now sadly deceased), and they are about 3x bigger than the Keck camera. The smaller the pixels, the more precisely the positions of the objects can be determined, which is the primary measurement to be made here.

Another interesting historical note: If Hubble, which has been around quite a while now, discovered these new satellites Nix and Hydra, then why weren’t these discovered *last* decade? . . . because the time allocation committee of Hubble didn’t feel it was worth a try. (And this was back when Pluto was a “planet”.)

http://spaceurope.blogspot.com/2007/10/plutos-family-portrait-with-david.html

Tholen wasn’t after surface details but the dynamics of the satellite system, so hasn’t done the requisite processing for the former.

Hat tip to unmannedspaceflight.com.

http://www.youtube.com/watch?v=e3cDdGKqp8E

Alex, you are quite right. Also, the forthcoming James Webb space telescope will observe at several IR wavelengths and will be able to detect very faint sources by virtue of being kept colder than can be achieved on Earth.

http://pluto2.punt.nl/upload/Pluto-Knochen_download.jpg

http://en.wikipedia.org/wiki/Image:Atmospheric_electromagnetic_transmittance_or_opacity.jpg

The net effect of this is that, while you can get really good resolution on earth by virtue of being able to build huuuuuge telescopes like the Keck observatory, you’re limited to a relatively narrow window of frequencies. As it happens, the Hubble mostly observes frequencies you could see on earth, but its lesser known companions in NASA’s Great Observatories program, observe gamma rays, x-rays in ways that fundamentally cannot be duplicated from within the earth’s atmosphere.

I think the thing that comes off a bit odd is the press release shouting ‘Highest resolution evah!! We pwnd Hubble’ when a moment’s googling can get higher res Hubble images. Bad PR, IMO, and they should anticipate it.

The Keck telescopes are about 10 m (diameter of objective mirror) compared with Hubble’s 2.3 or 2.4 m (I think – someone plese correct this if I’m wrong). Thus, the resolving power of each Keck telescope is theoretically about four times that of Hubble. Linking the two telescopes gives even better resolution. Additionally, with about 16 times the area (roughly, for one 10 m Keck versus Hubble), the Keck telescope can gather 16x as much light as Hubble and thus record objects that are that much fainter.

This is complicated by Keck’s being sited on the Earth’s surface and Hubble’s being in orbit.

Keck’s resolution is degraded by atmospheric turbulence. This is, to a large extent, compensated for by the use of adaptive optics, but Keck will still not be as good a scope as if it were in orbit. So, its resolution will be between 1 and 4 times as good as Hubble, depending on the extent to which the adaptive optics can compensate for atmospheric turbulence (and, presumably, on the seeing conditions).

Hubble does not have this limitation, but it is a smaller telescope.

Then there’s the time over which light is gathered: depending on the exact mechanics of the Keck telescope, its maximum exposure time will be limited to the amount of time the telescope can record the same piece of sky. Because the Earth rotates about 15° per hour, this will be no more than (say) about 8 – 12 hours for something near the ecliptic. (This also gives a hint about the star trails in the image: if the exposure was several hours, the Pluto system would have moved against the background stars. With the scope tracking Pluto, this results in the stars appearing as streaks rather than points).

However, there are times when Hubble’s orbital plane is approximately parallel to the direction of the Earth’s orbit. At these times, Hubble can face away from the sun and record exposures for many many hours (I believe the current longest exposure taken by Hubble was around 30 hours, for one of the Hubble Deep Field images). This cannot be done over the whole sky, because there are some directions in which the Earth would always obscure Hubble’s view for a part of each orbit. I think that, as long as Hubble is facing a direction that is approximately perpendicular to its orbital plane, it can take long exposures without the Earth getting in the way. This is not done all that often, because time on Hubble is very valuable.

So, you have the Keck telescopes with better resolution than Hubble and a larger area over which to collect light, but with physical limits to the exposure time; and, on the other hand, you have Hubble with a smaller objective but (in principle) longer exposure times available.

Thus, for a large object with faint features (such as a nebula, that may occupy several degrees across the sky), Hubble will be able to take excellent observations, whereas for smaller objects (such as Pluto), Keck is the better instrument.

I hope this is useful, and I also hope that, if I have my facts wrong, someone else will come along and correct them.

Ted: (Holds up toy plastic cow) “OK, now this one is SMALL, right? And those (points out of window) are FAR AWAY…”

You just wait until the high-res photos show up and we see the Face on Pluto. And the big caterpillar/worm thing that the scientific community will try to hush up by saying it’s actually a valley.

Actually, I’m waiting for the discovery of the Stonehenge replica at Pluto’s north pole.

How far away is pluto?