Those Dark Spots on Pluto

@Setanta,

Or they may be too dispersed. That's a very large chunk of space out there. The objects in the Kuiper belt may also have very small relative motion when they collide. There are lots of possibilities.

Interestingly, Charon seems to be short on craters as well. Lots of mysteries.

1 Reply

@rosborne979,

What struck me most about that "moon" is how close it is to Pluto. It's almost as though it were a dual dwarf planetary system.

0 Replies

@edgarblythe,

edgarblythe wrote:

I don't know if this is an actual photograph or an artist's rendering. If it is an actual photograph, those two are awfully damned close to one another. Phobos is only 5000 kilometers above Mars, but there is no doubt which is the planet and which is the satellite.

2 Replies

I don't recall what, if anything, was written in that regard when I copied the url. I was too excited to get a picture of the two of them to think about it.

0 Replies

@Setanta,

Setanta wrote:

I don't know if this is an actual photograph or an artist's rendering. If it is an actual photograph, those two are awfully damned close to one another. Phobos is only 5000 kilometers above Mars, but there is no doubt which is the planet and which is the satellite.

Here is the caption for that photo from the NASA Site

Quote:

New Horizons was about 3.7 million miles (6 million kilometers) from Pluto and Charon when it snapped this portrait late on July 8, 2015.
Credits: NASA-JHUAPL-SWRI
http://www.nasa.gov/feature/pluto-and-charon-new-horizons-dynamic-duo

Here is another image of the two.

http://www.nasa.gov/sites/default/files/styles/full_width_feature/public/thumbnails/image/pluto-and-charon-01.jpg?itok=1QsBZEmJ

The latest two full-frame images of Pluto and Charon were collected separately by New Horizons during approach on July 13 and July 14, 2015. The relative reflectivity, size, separation, and orientations of Pluto and Charon are approximated in this composite image, and they are shown in approximate true color.

Here is a video taken during the New Horizons approach which shows their wobbly orbit around a common center of mass which is outside either body.

0 Replies

Cool, Boss . . . thanks. I'd see that as a duel planetary system if they both waltz around a common center of mass.

0 Replies

Actually...the Earth and its moon dance around a common center of gravity. The center in our case lies inside the Earth.

And the Earth and Sun dance around a common center of gravity...as does every celestial body.

That one seems extreme...due to the huge size of Charon compared with Pluto.

0 Replies

That's a sterling example of how your ignorance makes you unable to make coherent judgments.

0 Replies

The moon is tidally locked to the earth. You can read about that by clicking here.

The Earth, however, is not tidally locked to the Sun, so the situations are not analogous. You can read about how tidal locking affects planets by clicking here. If the Earth were tidally locked to Sun, as the Moon is to the Earth, none of us would be here.

This is why it's a good idea not to make sweeping statements when you don't in fact know what the hell you're talking about.

0 Replies

Well...Setanta is wrong there, but the chances of Setanta ever acknowledging that is remote...so, who cares.

1 Reply

@Frank Apisa,

I presented evidence for the position i've taken. You have only produced your typical shop-worn sneers. If i'm wrong, present the evidence to that effect.

1 Reply

@Setanta,

What are you two even arguing about... this is my area of expertise, I could give an informed answer (if a Physics degree counts as being informed). But you two are at each other's throats so much it isn't even clear what the question is.

Maybe the question isn't what it is important.

3 Replies

@maxdancona,

If the question is whether the Earth and moon orbit around the same center of mass (except that the center of mass happens to be inside the Earth) than Frank is absolutely correct. This is true of any two orbiting bodies.

Tidal lock is irrelevant to this fact.

1 Reply

@maxdancona,

Thank you, Max...that is EXACTLY what the question was...and a reading of my post will bear that out.

0 Replies

@maxdancona,

maxdancona wrote:

What are you two even arguing about... this is my area of expertise, I could give an informed answer (if a Physics degree counts as being informed). But you two are at each other's throats so much it isn't even clear what the question is.

Expertise matters little in the presence of an expert.

max wrote:

Maybe the question isn't what it is important.

0 Replies

@Setanta,

Setanta wrote:

I don't know if this is an actual photograph or an artist's rendering. If it is an actual photograph, those two are awfully damned close to one another. Phobos is only 5000 kilometers above Mars, but there is no doubt which is the planet and which is the satellite.

Here are a few excerpts from Wikipedia:

"Pluto and Charon are sometimes considered a binary system because the barycenter of their orbits does not lie within either body.[22]"
"Pluto's . . . diameter is 2370 km"
http://en.wikipedia.org/wiki/Pluto

"Charon's diameter is 1,208 kilometres"
"The average distance between Charon and Pluto is 19,570 kilometres"
"The center of mass (barycenter) of the Pluto–Charon system lies outside either body. Because neither object truly orbits the other, and Charon has 11.6% the mass of Pluto, it has been argued that Charon should be considered to be part of a binary system with Pluto."
http://en.wikipedia.org/wiki/Charon_%28moon%29

-------------------------------------------------------------------------------------

By the way, totally off topic, but we have a new orbiter due to reach Jupiter next summer (2016):
http://en.wikipedia.org/wiki/Juno_%28spacecraft%29
http://missionjuno.swri.edu/

This fall, they will open up a messageboard where the public can propose and discuss ideas for which parts of Jupiter they should take images of. And come 2016 they will allow the public to vote on what to photograph:
http://missionjuno.swri.edu/junocam

Presumably not every picture will be decided by public vote. They’ll be after specific scientific data too. But it looks as if the public will choose some of the images that will be gathered.

There is also a proposal to send an orbiter/atmospheric probe to Uranus. However, no one has decided to actually go forward with the project yet:
http://www.nap.edu/reports/13117/App%20G%2023_Uranus_Orbiter_and_Probe.pdf

1 Reply

@oralloy,

Sure Oralloy,

Quote:

"The center of mass (barycenter) of the Pluto–Charon system lies outside either body. Because neither object truly orbits the other, and Charon has 11.6% the mass of Pluto, it has been argued that Charon should be considered to be part of a binary system with Pluto."

That doesn't effect the orbital math at all, it is just an argument over terminology. As I understand it, the question is whether Charon should be considered a dwarf planet in its own right.

The orbits of these two bodies still follow the same rules as the Earth and Moon system follow. Actually, our moon is gradually getting farther away from the Earth. At some point in the future the center of mass in the Earth moon system will be outside of the Earth.

0 Replies

@maxdancona,

Ah yes, Mr. Science, who can drive from Boston to Rochester in five hours, a distance he describes as 396 miles, with two stops for food and fuel, no less! If your math, or your honesty, are not better than that, your alleged credentials don't impress me.

Frank, one of the most simple-minded bullies here, was attempting to argue from analogy (look that up, if you have to). What he described, i.e., the relationship of the Moon to the Earth, and that of the Earth to the Sun, are not analogous. The moon being tidally locked is significant as he was attempting to argue, in his feeble-minded and hectoring manner, about the relationship of Charon to Pluto. See Oralloy's subsequent remarks, including sources, on the relationship of those two bodies to one another.

1 Reply

Here is an amazing account of a dual planetary system It describes two gas giants which are several times larger than Jupiter, and which are millions of miles apart.

University of Florida in Gainsville expert Eric Ford wrote:

“A planetary system with such closely spaced giant planets would be destroyed quickly if the planets weren't doing such a well synchronized dance. This makes it a real puzzle how the planets could have found their rhythm,”

That's more or less my reaction to the Charon-Pluto system. The moon is only 1.2% the mass of the Earth--Charon has almost 12% the mass of Pluto, alomost ten time as massive as the Moon as compared to the Earth. Obviously, Charon and Pluto are minuscule in comparison to the planets described in the above linked article--but it is a wonder that their relationship survives.

0 Replies

By the way, for those here who do not suffer a lack of imagination, the distinction between the Pluto-Charon relationship and the Earth-Moon relationship is dramatically significant. The Moon is not quite 240,000 miles from the earth, and is about 1.2% of the Earth's mass. Charon is less than 13,000 miles from Pluto, and has almost 12% of the mass of Pluto.

To translate that into terms of the Earth, and to supply the lack of imagination that people like Max suffer, consider this: the Moon, tiny little moon, far away moon, still has a profound impact on the oceans of our world--consider the tides. Yet what Max claims is just a matter of terminology is far more significant than Mr. Science makes it out to be. Imagine if, rather than the Moon, the Earth were being orbited by Mars. The mass of Mars is just less than 11% of the mass of the earth, but it'll do for this analogy. Imagine the Earth orbited by Mars, and Mars six times closer to the Earth than the Moon is now. That will give you some idea of what Max says is just a matter of terminology, and what Frank is trying to claim is analogous to the Earth-Moon relationship.

What a pair of rubes.

0 Replies

Those Dark Spots on Pluto

Related Topics

Quick Links

My Account

able2know