New planets discovered orbiting our Sun
Discussion
This is seven in the eye for the IAU.
http://www.thetimes.co.uk/edition/news/moon-rises-... (Apologies for quoting a source that does not capitalise Moon.)
It would appear that there are many more planets orbiting the Sun that originally thought; seven in fact. This argument is over the Moon, Europa, Ganymede, Titan and Enceladus. Not to forget that big one sometimes orbiting in the Ort Cloud.
It will come as no surprise to hear that Alan Stern, of New Horizons fame, is the leader in the campaign to get these moons labelled as planets.
I remember listening to, I think, Carl Sagan when he said the proper way to think of the Earth and Moon is as a dual planet system. His point was more gravitational than size I think but I agreed with him. I hope he appreciated my support.
http://www.thetimes.co.uk/edition/news/moon-rises-... (Apologies for quoting a source that does not capitalise Moon.)
It would appear that there are many more planets orbiting the Sun that originally thought; seven in fact. This argument is over the Moon, Europa, Ganymede, Titan and Enceladus. Not to forget that big one sometimes orbiting in the Ort Cloud.
It will come as no surprise to hear that Alan Stern, of New Horizons fame, is the leader in the campaign to get these moons labelled as planets.
I remember listening to, I think, Carl Sagan when he said the proper way to think of the Earth and Moon is as a dual planet system. His point was more gravitational than size I think but I agreed with him. I hope he appreciated my support.
Eric Mc said:
Also, one of the key definitions of a planet is that it has to orbit the sun directly and not orbit another primary planetary body.
On that basis, large moons such as our Moon and Ganymede, Titan etc can't be classed as planets because they orbit a planet rather than the sun directly.
At the end of the day, what we chose to label these objects as is almost irrelevant. We came up with definitions and categories for our own labelling purposes and convenience. The important thing is what we can learn about these worlds - not what box we chose to put them in.
Stern and his supporters are after changing the definition. The Moon does not orbit the Earth of course, and that was the point of Sagan's suggestion. More to the point, why should orbiting a planet stop a large body being classified as a planet? It still orbits the Sun just not steadily. Titan's bigger than Mercury and not far short of Mars. On that basis, large moons such as our Moon and Ganymede, Titan etc can't be classed as planets because they orbit a planet rather than the sun directly.
At the end of the day, what we chose to label these objects as is almost irrelevant. We came up with definitions and categories for our own labelling purposes and convenience. The important thing is what we can learn about these worlds - not what box we chose to put them in.
Seems unfair. Whatever the definition it will be seen as arbitrary by some.
CrutyRammers said:
Indeed. We call them moons so that everyone knows that they orbit the main planet. Calling them planets as well will just mean that we have to come up with another name for "small planet going round a larger one"
Could it not be that a planet can also be a moon? Some Gump said:
Nah, not buying it. Titan can be as big as it wants, its tiny next to planet it orbits so under the definition as always had been, it's Jupiter's moon, they are not binary planets.
To me it's as daft as reclassifying a great Dane as a small horse because it's bigger than a wee pony. You can't ignore loads of things and just define by size.
Mind, you might want to remember I'm a Luddite, who still refuses to think of the planet Pluto as anything less than a small planet.
Did Titan always orbit Saturn or was it, perhaps, a free spirit and then captured? Perhaps a captured moon planet?To me it's as daft as reclassifying a great Dane as a small horse because it's bigger than a wee pony. You can't ignore loads of things and just define by size.
Mind, you might want to remember I'm a Luddite, who still refuses to think of the planet Pluto as anything less than a small planet.
A Great Dane is normally bigger than some horses, also called ponies, but the difference between them is that they are different animals. Most moons are made of the same stuff as planets.
The Moon and Earth orbit their common centre of gravity so I can see that as a reason to have us as a dual planet system.
Alan Stern is the bloke pushing this. He was, if memory serves, a leader in the campaign to stop Pluto being ignored.
perdu said:
Dead horse flogging time Derek
I'm not suggesting it is a good idea, and I haven't said whether I'm for or against it. However, given that this has been put forward by a group of NASA scientists and the bloke in charge of the New Horizons mission is leading it, it shouldn't be ignored. They might know what they are talking about. Isn't science all about change? Isn't it the signature trait of scientists a willingness to consider all options, including those off the wall? Stern stated that: “It’s [the definition of planet] an awful definition; it’s sloppy science and it would never pass peer review.”
Is, for instance, Charon still a satellite? That, surely, is a dual dwarf planetary system.
We should change definitions as they become difficult to justify. After all, what would QI do if we didn't?
Eric Mc said:
Pluto has FIVE moons (or is a six planet system as Derek would have us believe 
) - Charon, Nix, Styx, Kerberus and Hydra (not soft rock band by the way).
Pluto would be a silly situations with Derek's suggested nomenclature with a dwarf planet (Pluto) having five actual "planets" orbiting it. It would all get very confusing.
I think the current nomenclature is pretty much the best they've come up with so far. Things need to change when new discoveries are made.
The reason Pluto's definition was changed from "Planet" to "Dwarf Planet" was the discovery of literally hundreds if not thousands of Pluto like objects orbiting further out - what are referred to as Kuiper Belt Objects. It seems Pluto is really a member of that group rather than a bona fide planet in the normal sense.
At the end of the day, what we chose to call things is only for our own convenience. The objects just "are" - whatever we name them as.
As I said earlier, getting hung up on what category we want to place planetary bodies in is really a waste of time. It's far better to devote time and effort to actually studying them and trying to understand WHAT they actually are and how geological processes work on them.
Just to clarify: it is not my suggestion about the nomenclature of planets. Much as I would like to claim responsibility, I think that Stern's authority overrides mine, and by some distance. ) - Charon, Nix, Styx, Kerberus and Hydra (not soft rock band by the way).Pluto would be a silly situations with Derek's suggested nomenclature with a dwarf planet (Pluto) having five actual "planets" orbiting it. It would all get very confusing.
I think the current nomenclature is pretty much the best they've come up with so far. Things need to change when new discoveries are made.
The reason Pluto's definition was changed from "Planet" to "Dwarf Planet" was the discovery of literally hundreds if not thousands of Pluto like objects orbiting further out - what are referred to as Kuiper Belt Objects. It seems Pluto is really a member of that group rather than a bona fide planet in the normal sense.
At the end of the day, what we chose to call things is only for our own convenience. The objects just "are" - whatever we name them as.
As I said earlier, getting hung up on what category we want to place planetary bodies in is really a waste of time. It's far better to devote time and effort to actually studying them and trying to understand WHAT they actually are and how geological processes work on them.
Also regarding the dual dwarf planetary system of Pluto/Charon, if you search online you will find that there has been such a suggestion for years, from 1978 I would assume.
You suggest things are what we decide to call them. I think that's the point Stern is making. He is only after clarifying the definition, ensuring that it is clearer and more useful. Nothing stops us from changing the names. It is illogical to call them planets, or even wanderers, just because that's what we always called them.
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