If it has a ring it must be a planet! Re-instate Pluto's Planetary Status NOW!.............
Posted on 08/08/2011 6:20:20 AM PDT by Red Badger
Dust from Pluto's satellites ought to form a faint ring around the dwarf planet, according to new calculations
Until recently, the only ring in the Solar System was Saturn's. But in 1960s and 70s, astronomers discovered rings around Uranus and Neptune. Meanwhile, the Voyager 1spacecraft sent back images of Jupiter's ring.
To be sure, these rings are much less impressive than Saturn's but the implications are clear: rings seem much more common than astronomers once thought. Perhaps they are even the norm.
And that raises an interesting question: could Pluto possibly have a ring?
The observational evidence is that Pluto does not have a ring. The best images are from the Hubble Space Telescope and they show nothing.
But today, Pryscilla Maria Pires dos Santos and pals at UNESP-São Paulo State University in Brazil say that Pluto ought to have a ring after all, but one that is too faint for Hubble to spot.
Their conclusion comes from modelling the way that micrometeorite impacts on Pluto's satellites, Nix and Hydra, ought to send dust into orbit about the dwarf planet.
This dust inevitably spirals into Pluto and its satellites because of its interaction with the solar wind. In this way, the dust is removed from orbit.
But that doesn't mean it can't form a ring. The important question is whether the dust can be replaced as quickly as it is removed.
Pires dos Santos and co calculate that the dust initially forms a ring about 16,000 km wide, encompassing the orbits of both Nix and Hydra. However, the solar wind then removes about 50 per cent of the dust within a year.
However, that still leaves enough to form a ring, albeit it an extremely faint one. "A tenuous ring...can be maintained by the dust particles released from the surfaces of Nix and Hydra," say Pires dos Santos and co.
They calculate that its transparency (or optical depth) has a value of 10^-11. By comparison, the main ring of Uranus has a transparency of between 0.5 and 2.5.
Hubble ought to be able to to see a ring around Pluto with a transparency of about 10^-5 so it's no surprise that it hasn't seen the ring that the Brazilian team predict. There's no way to see such a ring directly from Earth.
Fortunately, there is a way to settle the matter.
The New Horizons spacecraft is currently on its way to Pluto, equipped not with a camera capable of seeing the ring but with a dust counter that should do the trick instead. If this probe finds itself in the lightest of dust clouds when it arrives on 14 July 2015, we'll finally know for sure.
Ref: arxiv.org/abs/1108.0712: Small Particles In Pluto's Environment: Effects Of The Solar Radiation Pressure
If it has a ring it must be a planet! Re-instate Pluto's Planetary Status NOW!.............
Congratulations.
My wishes for a long , happy marriage.
He and Goofy are engaged?
Eh. Who cares, it’s not a planet, right? If it was we’d have 11 or 12 planets now but that’s too inconvenient.
That's getting personal.
A ring around Uranus? Well I’ll be!!!!
Ping
Hey, now!
Note: this topic is from 8/08/2011. Thanks Red Badger.
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Note: this topic is from 8/08/2011. Thanks Red Badger. Another 'extra, extra' to the APoD list.
This little planetoid has a lot of interesting things about it, it’s like a mini-Saturnian system.
So they’re using Hubble to get a view of Pluto, but the pictures leave much to be desired. I understand optics enough to understand how they could see so far away, but why couldn’t terrestrial multi-optic telescopes get a really clear view of Pluto from here? For that matter, why can’t Hubble or other high-powered scopes get better, closer, clearer views of planets in our solar system? It seems we’re creating scopes that can see farther and farther out, but we can’t get close-up, high-resolution images of plants in our own solar system.
They move.........
I don't buy that as an excuse. I made a stepping motor from scratch using parts from Radio Shack and created a mobile scope platform for my 14" light bucket and recorded two hours of video focused on Mars' transit through a clear winter night sky. It cost me somewhere in the neighborhood of $20 to build.
You can't tell me that terrestrial scopes and/or orbital scopes couldn't do the same thing on a much more precise scale.
After several thousand years of civilization, they are the best images ever acquired.
Pluto is difficult to image because it is small, very far away, and light intensity follows the inverse square law.
Terrestrial scopes have atmosphere as a limiting factor.
Hubble has a different limitation, it’s moving at 7500 meters per second..............
Yeah, ya know I didn’t think about size. My apologies on that. Brain is a little fuzzy this morning.
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