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.
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.
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.
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.
Eric Mc said:
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.
Since the Earth and Luna orbit their common barycentre, which lies within Earth, but some way from the centre; that's debatable.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.
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.
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.
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"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.
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.
^ I wasn't about back when titan started orbiting, so I don't know. However, once it reached a stable orbit, it became a moon. To pretty much anyone, that's what a moon is - a small thing going round a big thing. If earth magically teleported to be near jupiter, and it started going round and rond for a laugh, our planet would be a moon of jupiter.
You can get all Sheldon and say well the Moon doesn't orbit the centre of Earth, and the pair orbit offset - but IMO that's just more visible because we have 1 moon not 3 or 4. I'm quite confident that the Sun itself has motion caused by jupiter, it's just that it's tiny due to the relative masses and distances involved. IMO this doesn't approach what I'd think of as a binary pair - when 2 far more similar masses are involved then to me that's fine.
I'm sure the leaders of the scientific field will come to the right conclusion - but from a popular science point of view, no-one is going to win an argument that the moon isn't a moon, unless they're David Niven.
You can get all Sheldon and say well the Moon doesn't orbit the centre of Earth, and the pair orbit offset - but IMO that's just more visible because we have 1 moon not 3 or 4. I'm quite confident that the Sun itself has motion caused by jupiter, it's just that it's tiny due to the relative masses and distances involved. IMO this doesn't approach what I'd think of as a binary pair - when 2 far more similar masses are involved then to me that's fine.
I'm sure the leaders of the scientific field will come to the right conclusion - but from a popular science point of view, no-one is going to win an argument that the moon isn't a moon, unless they're David Niven.
Derek Smith said:
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? Ultimately we need names for things which people understand. The above example re: the sun and planets also orbiting a common centre is quite correct. Planets are from the same stuff as stars, they just didn't get big enough. So lets just call everything a "star" and have done.
grumbledoak said:
NASA should be striving for some bigger achievements in the future, not "bigging up" it's past.
It is - but its hamstrung by restricted budgets.Having said that NASA does lots of stuff all the time - it's just that the mainstream media doesn't pay much attention to its programmes. If you look them up, you might be amazed at the hundreds of different projects they are actively involved in all the time.
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?
Some Gump said:
I'm quite confident that the Sun itself has motion caused by jupiter, it's just that it's tiny due to the relative masses and distances involved. IMO this doesn't approach what I'd think of as a binary pair - when 2 far more similar masses are involved then to me that's fine.
actually the barycenter of the Jupiter/Sun orbit lies outside the sun's surface, so an even better example than Earth/Moonnice animation in this link
http://www.iflscience.com/space/forget-wha-you-hea...
Derek Smith said:
Is, for instance, Charon still a satellite? That, surely, is a dual dwarf planetary system.
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.
Eric Mc said:
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.
Amen 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.
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