Why can't we take good pictures of Pluto?

[billions]

Yes, that is correct, they are all at their maximums. I grabbed the data from http://nssdc.gsfc.nasa.gov/planetary/factsheet/

It's really incredible how small some of the planets would appear at their minimums, but that would mean they are on the opposite side of the sun, and thus in the sky during daytime. A lot of our viewing is when they are on the larger end of the spectrum.

 

[Astro_Robert]

<<As the story goes, Clyde Tombaugh inferred that Pluto must be out there based on it's gravitational influence on Neptune's orbit. >>

Actually, when Voyager2 passed by Neptune, the gravity asist it recieved allowed a more accurate estimate of Neptune's mass which did away with the need for a Neptune perturber. And in fact Pluto has no where near enough mass to perturb Neptune anyway.

Pluto was found because Tombaugh was looking for a Neptune perturber as astronomers did not yet have more accurate data. As the namesake and one of the alrgest of the Plutinos it will always have a place in everyone's heart.

 

[drwayne]

"As the story goes, Clyde Tombaugh inferred that Pluto must be out there based on it's gravitational influence on Neptune's orbit"

Actually Tombaugh was a technician responsible for taking, and comparing images, he was not the
scientist behind the theory.

Wayne

 

[gvtoll]

Size and brightness are only two factors - they are compounded by another key one -- motion. Galaxies, stars and nebula are relatively still from our perspective. Generally, you can repeatedly take pictures of them night after night and, within limits, add up all of the exposures to capture a LOT of light. The Hubble Ultra Deep Field "image", for instance, was the sum of a million seconds of exposures - more than 10 days.

Planets not only circle the sun with a noticeable motion, but they rotate. Taking crisp photos of planets is like getting great shots of fast moving athletes - you'd better have lots of light and a big lens.

Pluto doesn't present a lot of light and it rotates every 6.4 days. That means a feature on the surface will pass across what we can see in 3.2 days. Its position will change by 10% of Plutos visible diameter in just 8 hours. So, to get pictures with a resolution of just 5% of the visible diameter would limit exposure times to 4 hour or less exposures - compared to 10 days for the ultra deep field. Even if Pluto is relatively brighter than the distant galaxies, the task of getting quality photos using even the Hubble become daunting.

The math for this was done quickly, so hopefully, I made no gross errors. Let it be said that even Jupiter, as big and bright as it is, with it's 10 hour rotation it presents a problem for amateur astronomers in getting high resolution. It won't stand still.

 

[drwayne]

Many years ago, an astronomy professor at Vassar had us read a book on Tombaugh. There was a fascinating
story in there about when Tombaugh finally went away to college (he had not done that when he made the
discovery) - and he signed up for Astronomy 101. The instructor, upon finding out that he was in the course
summarily threw him out, telling him to go take an advanced course, that he wasn't going to have the
discoverer of Pluto in his introductory astronomy class.

Wayne

 

[Anglocowboy]

So is this really Pluto's color?

http://upload.wikimedia.org/wikipedia/c ... 2-2003.jpg

I always saw Pluto depicted as blue in pictures during my childhood. Now knowing that back then, Pluto had just as good a chance at being red as it did blue, it's still odd to see red in that picture.

 

[CalliArcale]

As near as anyone can tell, yes, that is Pluto's color. It's an oddball. The pinkish color suggests there may be a lot of organic chemicals on its surface. It also lends credence to the notion that it is related to Triton, Neptune's largest moon. Triton almost certainly did *not* form around Neptune, but was instead captured by it. It's very different from Neptune's other moons and, most tellingly, orbits retrograde -- the largest object in the solar system known to do so. Like Pluto, it's kind of ruddy colored.

Triton is also very active, volcanically, the result of tidal stresses being so close to Neptune, and aggravated by its retrograde motion. Will Pluto also be volcanically active? Maybe; it does have an unusually large companion (Charon) which could help drive volcanism. But Pluto and Charon are mutually synchronous (they always point the same faces towards one another) which ought to reduce the stress. So, it's hard to say. It will be very interesting to see what New Horizons finds!

 

[yale_s]

As Calli pointed out, Pluto (and its likely cousin Triton) has a reddish tint. It appears that KBOs fall into two broad color classes, bluish and reddish. The New Horizons team plan on sending the robot to a bluish object after passing the reddish Pluto.

- Yale Simkin

 

[yevaud]

Holy flipping moley, Yales, you old Dog! How's it shaking?!

(PM me, let me know where you're hanging these days, please)

 

[yale_s]

Elguapo, Yevster...
More stabs from the past!

I really have missed posting here.

Everything's shaking as well as could be expected. (I don't shake too hard..., I want to avoid stress fatigue cracks!)

 

[starchild218]

I don't quite understand why we can't take good pictures of Pluto or comets in the kuiper belt but can detect galaxies essentially 13 billion light years away
Just wondering

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You were not alone with that question. I had recently asked myself that same not that long ago, shortly before I saw the image, I think Origin had the link to. Although it shows 'nothing worth writing home about'... :lol: it is somewhat better than what we had.
I'm confused or maybe just got it wrong, but do we not have two spacecraft launched a few years back that are supposed to be going past all the planets onto interstellar space? If so, wouldn't one of them be able to get a much better picture of Pluto...& Pals....or do we still have months & months..ete..before any pictures will get back to Earth, or just no pictures at all??
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[drwayne]

One thing to keep in mind when thinking about this stuff. There is a tendency to think in terms of when a probe
is at the distance of a planet's orbit, it must be close to it. The reality is that, depending on the timing of the probe,
it can actually be further from the planet in question that the Earth is, simply because the planet is elsewhere in
its orbital path.

The hard part of rendevous - you have to be at the right place and time, and in the right velocity state.

Wayne

 

[starchild218]

As Calli pointed out, Pluto (and its likely cousin Triton) has a reddish tint. It appears that KBOs fall into two broad color classes, bluish and reddish. The New Horizons team plan on sending the robot to a bluish object after passing the reddish Pluto

- Yale Simkin

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Just saw your & a few others post after I'd posted. Thats very nice indeed, and I learned something... 'thanks guys'... my question has pretty much been answered also.
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