Posted on: Feb 4 2016, 11:31 PM | |
Junior Member Group: Members Posts: 78 Joined: 16-October 12 From: Pennsylvania Member No.: 6711 |
Even if the inclination instability model was correct, there could still be one or more objects with planetary mass in the outer solar system. Ceres contains a third of the mass in the asteroid belt and while the case may not be so severe in a large disk, when dealing with a disk of one or more earth masses, you will start reaching planetary masses rather quickly. There could be subjects ranging from Mercury to Mars and greater. I've read before that if Ganymede and Titan would be considered planets if they orbited the sun. That was then, now if we find larger objects out there, wouldn't they still be called planets? |
Forum: Telescopic Observations · Post Preview: #229421 · Replies: 105 · Views: 1430836 |
Posted on: Jan 20 2016, 11:37 PM | |
Junior Member Group: Members Posts: 78 Joined: 16-October 12 From: Pennsylvania Member No.: 6711 |
Gladstoner. I was under the impression that the such ruled out any brown dwarf or massive planets currently around the sun. There could have been one out there once and was since lost. Or maybe an interstellar interloper made a close pass to the solar system and went on its way. |
Forum: Telescopic Observations · Post Preview: #229134 · Replies: 105 · Views: 1430836 |
Posted on: Jul 15 2015, 10:40 PM | |
Junior Member Group: Members Posts: 78 Joined: 16-October 12 From: Pennsylvania Member No.: 6711 |
It's almost impossible for Pluto to capture a body spontaneously. You'd need three bodies to carry that out, and Pluto never comes within 11 AU of anything large. It almost has to be a collision between Pluto and another body that led to the Pluto-Charon system. A Giant Impact and capture of an intact Charon would create the tidal forces and the resurfacing that we are seeing today. |
Forum: New Horizons · Post Preview: #223665 · Replies: 1286 · Views: 20589316 |
Posted on: Jul 15 2015, 10:11 PM | |
Junior Member Group: Members Posts: 78 Joined: 16-October 12 From: Pennsylvania Member No.: 6711 |
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Forum: New Horizons · Post Preview: #223656 · Replies: 1286 · Views: 20589316 |
Posted on: Jul 15 2015, 01:04 AM | |
Junior Member Group: Members Posts: 78 Joined: 16-October 12 From: Pennsylvania Member No.: 6711 |
Congratulations to New Horizons! |
Forum: New Horizons · Post Preview: #223428 · Replies: 1286 · Views: 20589316 |
Posted on: Jul 13 2015, 09:26 AM | |
Junior Member Group: Members Posts: 78 Joined: 16-October 12 From: Pennsylvania Member No.: 6711 |
It is also possible that the body that impacted Pluto was Charon itself. Charon was a separate body orbiting the Sun and hitting Pluto slowed it down enough to be captured. The tidal stresses created would have resurfaced both objects. It is difficult for a giant impact to create body as large as Charon in relation to Pluto. Charon has an eighth Pluto's mass. Our moon is an eightieth the mass of Earth. |
Forum: New Horizons · Post Preview: #223007 · Replies: 729 · Views: 559093 |
Posted on: Jul 11 2015, 11:20 PM | |
Junior Member Group: Members Posts: 78 Joined: 16-October 12 From: Pennsylvania Member No.: 6711 |
It is interesting that Pluto seems to be two faced like our moon. The chaos terrain mostly occupies the hemisphere facing Charon. For anyone who hasn't seen it yet. New Horizons will be mostly imaging the far side at closest approach. The media seems calling this hemisphere the "far side" instead of the near side because of New Horizon's trajectory. They need to use the right definitions! |
Forum: New Horizons · Post Preview: #222849 · Replies: 729 · Views: 559093 |
Posted on: Jul 11 2015, 10:55 PM | |
Junior Member Group: Members Posts: 78 Joined: 16-October 12 From: Pennsylvania Member No.: 6711 |
Oh, I am sure NH will spot smaller details on the other hemisphere. But it seems to lack the large scale chaos terrain this hemisphere does. And that is the dynamic stuff the public likes. Why else are textbooks full of photos of Venus in Infrared? |
Forum: New Horizons · Post Preview: #222840 · Replies: 729 · Views: 559093 |
Posted on: Jul 11 2015, 10:47 PM | |
Junior Member Group: Members Posts: 78 Joined: 16-October 12 From: Pennsylvania Member No.: 6711 |
That is the side of Pluto that is going to be in the textbooks. You can count on that. |
Forum: New Horizons · Post Preview: #222836 · Replies: 729 · Views: 559093 |
Posted on: Jul 11 2015, 10:25 PM | |
Junior Member Group: Members Posts: 78 Joined: 16-October 12 From: Pennsylvania Member No.: 6711 |
Charon seems to have more similarities to Triton than Pluto does. Both bodies seem to have been captured and experienced significant heating that resurfaced them with that present jagged football pattern. Pluto very likely has had heating too, but has gone about it differently. |
Forum: New Horizons · Post Preview: #222827 · Replies: 729 · Views: 559093 |
Posted on: Jun 14 2015, 02:50 PM | |
Junior Member Group: Members Posts: 78 Joined: 16-October 12 From: Pennsylvania Member No.: 6711 |
I don't know why using a dart board for Pluto-Charon feels so appropriate. It just works. |
Forum: New Horizons · Post Preview: #221273 · Replies: 519 · Views: 378059 |
Posted on: Jun 14 2015, 02:42 PM | |
Junior Member Group: Members Posts: 78 Joined: 16-October 12 From: Pennsylvania Member No.: 6711 |
This accomplishment is on par with landing Shoemaker on Eros for me. |
Forum: Rosetta · Post Preview: #221271 · Replies: 172 · Views: 273601 |
Posted on: Jun 3 2015, 12:41 AM | |
Junior Member Group: Members Posts: 78 Joined: 16-October 12 From: Pennsylvania Member No.: 6711 |
Trying to understand Pluto without Charon is like trying to put a puzzle together with only half the pieces. Or with a quarter of the pieces, in accordance with the square-cube law. |
Forum: New Horizons · Post Preview: #220895 · Replies: 519 · Views: 378059 |
Posted on: May 28 2015, 09:21 AM | |
Junior Member Group: Members Posts: 78 Joined: 16-October 12 From: Pennsylvania Member No.: 6711 |
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Forum: New Horizons · Post Preview: #220728 · Replies: 519 · Views: 378059 |
Posted on: May 13 2015, 10:39 AM | |
Junior Member Group: Members Posts: 78 Joined: 16-October 12 From: Pennsylvania Member No.: 6711 |
Too soon to tell unfortunately. Impacts can create rifts too, and Ceres has had an awful lot of them. |
Forum: Dawn · Post Preview: #220330 · Replies: 460 · Views: 1082186 |
Posted on: May 13 2015, 10:31 AM | |
Junior Member Group: Members Posts: 78 Joined: 16-October 12 From: Pennsylvania Member No.: 6711 |
All five this early, awesome. That is all the known moons down. Now we keep watch for the unknowns (if they exist). |
Forum: New Horizons · Post Preview: #220328 · Replies: 519 · Views: 378059 |
Posted on: Mar 6 2015, 12:54 AM | |
Junior Member Group: Members Posts: 78 Joined: 16-October 12 From: Pennsylvania Member No.: 6711 |
I'm sure that one of the key questions for Dawn is does Ceres have an ocean or did it have one in the past? If either is true, it would generate a lot of interest. The currently available key dates (more or less) from now until December this year: 6 March: Dawn's orbital capture by Ceres (61,000 km) 10 April: OpNav 6 (21,000 km, 306 pixels) 14 April: OpNav 7 (14,000 km, 453 pixels) 23 April: Dawn reaches RC3 orbit (13,500 km) May: Dawn reaches survey orbit (4,400 km) July: Dawn reaches high-altitude mapping orbit, HAMO (1,470 km) December: Dawn reaches low-altitude mapping orbit, LAMO (375 km) (from here and the usual table) So Dawn's mapping orbit starts the same month that New Horizon's Pluto flyby occurs. What a coincidence! |
Forum: Dawn · Post Preview: #218648 · Replies: 756 · Views: 1703727 |
Posted on: Feb 15 2015, 03:16 PM | |
Junior Member Group: Members Posts: 78 Joined: 16-October 12 From: Pennsylvania Member No.: 6711 |
Couldn't they do that with any object mapped by radar? Like, lets say, Venus? |
Forum: Titan · Post Preview: #218030 · Replies: 166 · Views: 213855 |
Posted on: Feb 15 2015, 03:09 PM | |
Junior Member Group: Members Posts: 78 Joined: 16-October 12 From: Pennsylvania Member No.: 6711 |
Ceres has about twice the radius of Enceladus (see diagram). I think it's probably Enceladus that's anomalous in its size class for being so round. I was going to post something like that but you beat me. Good job. Most objects about Ceres size are heavily cratered and without any neighbors Ceres can't resurface without a giant impact. And if there isn't a trick of the light and Ceres dichotomy is real, than that just reminds me of Mars, whose hemispheres are significantly from each other for reasons not yet well understood. And I think we can all agree that Mars is unambiguously a planet. |
Forum: Dawn · Post Preview: #218029 · Replies: 756 · Views: 1703727 |
Posted on: Feb 15 2015, 04:47 AM | |
Junior Member Group: Members Posts: 78 Joined: 16-October 12 From: Pennsylvania Member No.: 6711 |
Fantastic work Gerald! One has to say Ceres, at this point, looks a lot more like an Asteroid than a "Dwarf Planet". What are you expecting a dwarf planet to look like? Ceres is the first dwarf planet that has been encountered by humanity since the definition was termed by the IAU. |
Forum: Dawn · Post Preview: #218018 · Replies: 756 · Views: 1703727 |
Posted on: Feb 13 2015, 04:17 AM | |
Junior Member Group: Members Posts: 78 Joined: 16-October 12 From: Pennsylvania Member No.: 6711 |
Those are incredible. It is nice that we can finally start studying a large ellipsoid besides Iapetus. And we don't know very much about Iapetus! |
Forum: Dawn · Post Preview: #217942 · Replies: 756 · Views: 1703727 |
Posted on: Feb 12 2015, 07:16 PM | |
Junior Member Group: Members Posts: 78 Joined: 16-October 12 From: Pennsylvania Member No.: 6711 |
If we weren't allowed to speculate than this forum would be quite a bit smaller! Today makes the beginning of an exciting week for the Dawn mission. Like was explained a couple pages back, from today to the 19th, Ceres is going to triple in resolution. |
Forum: Dawn · Post Preview: #217919 · Replies: 756 · Views: 1703727 |
Posted on: Jan 27 2015, 08:46 PM | |
Junior Member Group: Members Posts: 78 Joined: 16-October 12 From: Pennsylvania Member No.: 6711 |
Perhaps this is an indication that Ceres formed beyond the snow line? |
Forum: Dawn · Post Preview: #217430 · Replies: 756 · Views: 1703727 |
Posted on: Nov 17 2014, 03:16 PM | |
Junior Member Group: Members Posts: 78 Joined: 16-October 12 From: Pennsylvania Member No.: 6711 |
Finding out the path makes the landing even more amazing. Philae could have easily came down on that bolder or hit the cliff and yet it survived. I have to agree with the team that so many things could have gone wrong, it is amazing it went so right! |
Forum: Rosetta · Post Preview: #215423 · Replies: 1412 · Views: 1204367 |
Posted on: Nov 13 2014, 12:42 PM | |
Junior Member Group: Members Posts: 78 Joined: 16-October 12 From: Pennsylvania Member No.: 6711 |
Yeah, most of the comets geology seems to be the results of sublimation.. |
Forum: Rosetta · Post Preview: #215044 · Replies: 1412 · Views: 1204367 |
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