sphenisc
Philosopher
- Joined
- Jul 14, 2004
- Messages
- 6,092
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A planet is the only thing in it's own orbit that is orbiting the sun. That works for me.
Not even the IAU go that far...that makes Mercury the only planet.
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A planet is the only thing in it's own orbit that is orbiting the sun. That works for me.
I think 'having cleared it's own orbit' is a perfect definition for a planet.
Why? It's a strange requirement which doesn't really correspond to what's important about being a planet.
Not even the IAU go that far...that makes Mercury the only planet.
What is important about being a planet?
What is important about being a planet? (genuinely want to know as it's all a little abrirary and the only thing that I can think distinguishes the big, historic things we call planets from the other stuff out there is that they have cleared (or mostly cleared) their own orbit.
That's why I was wondering if the Webb could be used once we think we know where it should be with more certainty then we currently have. It was seeing the images from Jupiter and Mars that made me think about it. I don't know why but I had thought the local planets would have been "too bright" i.e. too hot for the Webb to get good images.
And Venus, yes? (no moons)
To be a planet a body has to: orbit its star; not orbit another body; not be made entirely of imagination, antimatter, or dairy products; identify as a planet; be gravitationally stabilized into the shape of a sphere, cylinder, or balloon animal; not be delinquent on its student loans; have women; not be too remote to make an effective demonstration; have accessible rest rooms; be at least 17% natural ingredients; have a lively party atmosphere or an atmosphere of foreboding; not be too small for the both of us; have a Queen; and be worth saving even if you've just about given up hope.
There are five of these in the Solar System, but their names and locations are closely guarded secrets.
To be a planet a body has to: orbit its star; not orbit another body; not be made entirely of imagination, antimatter, or dairy products; identify as a planet; be gravitationally stabilized into the shape of a sphere, cylinder, or balloon animal; not be delinquent on its student loans; have women; not be too remote to make an effective demonstration; have accessible rest rooms; be at least 17% natural ingredients; have a lively party atmosphere or an atmosphere of foreboding; not be too small for the both of us; have a Queen; and be worth saving even if you've just about given up hope.
There are five of these in the Solar System, but their names and locations are closely guarded secrets.
Hmm, browsing at random through this thread, and glancing at some of the posts about Pluto, I got to wondering what exactly it is that actually sets apart a planet from a ...not planet. Was idly wondering if I should click around a bit --- or whether, as happens far more frequently, I should open a search page with the search terms "how is a planet defined", then bookmark it, and then forget all about it. Clearly now I need to do neither: a better more exhaustive list of things a planet is, or should be, I don't think I'm likely to find anywhere else. Nice!
.1. It must orbit a star (in our cosmic neighborhood, the Sun).
2. It must be big enough to have enough gravity to force it into a spherical shape.
3. It must be big enough that its gravity cleared away any other objects of a similar size near its orbit around the Sun
Though one could argue that the Earth is not a planet as it orbits the centre of gravity of the Earth-Moon system, rather than the sun. Or if you disagree how much bigger does the moon have to be before that is a planet or the earth is not a planet?
The currently used definition of planet seems to me to be extremely logical and appropriate. I really don't get why some have so much of an issue with it.
Dr. Becky had a terrifying idea in this video that planet nine might be a black hole.
Too close, too close. Push it away.
His bad is this news,Short version: the grating wheel is grating.
His bad is this news,
Worse would be if it stuck in between settings.How bad is this news? Not sure, but if that wheel lost function I think it would mean that camera would be stuck in one of it's three wavelength settings.
Strikes me that deciding what criteria do and don't qualify a body for the label "planet" isn't actually science, so the matter of science's honesty doesn't arise.
Last time I checked, the reason Pluto was demoted was because if Pluto fits the definition, then potentially hundreds more objects would also be planets, and that's just too confusing and high effort for schoolteachers to keep up with.
Do anybody know why Ceres was demoted originally?
Originally considered a planet, it was reclassified as an asteroid in the 1850s after the discovery of dozens of other objects in similar orbits
This thread is about the JWST, the most expensive, advanced, powerful and incredible space telescope ever, yet there seems to be so little new images and information being published that this thread is relegated to debating what a planet is. Why such an apparent dearth of new images and information? Is it there but I’m missing it, or is it all just for the boffins now?
If they don’t keep the non-boffins in the loop some will start to make things up . . . “What are they hiding? Alien life? Big Bang/Expanding Universe models are wrong? Evidence of a god? The Earth is actually flat? Some reason we’re all doomed? etc?” . . . It’s a worry, I tells ya.
The actual science isn't being done by NASA per se.
The team that proposed a particular observation gets
some privileged time with the data. Then it goes public.
Do anybody know why Ceres was demoted originally?
On Sept. 21, 2022, the James Webb Space Telescope delivered the clearest view of Neptune’s rings in more than 30 years. Webb’s Near-Infrared Camera (NIRCam) captured several bright, narrow rings as well as the planet’s fainter dust bands. Voyager 2 was the last to detect some of these rings during its flyby in 1989, but this is the first time we have an infrared image of them.
Just unbelievably surprising and beautiful.
TIL that Triton has an albedo of 0.76, which is pretty high. Earth has an albedo of 0.39.Triton is so bright it looks like a star.
Thanks for this in particular. I was hoping there was somewhere I could just flip through some pics.
Yeah I noticed that too.That is very cool. Although the gentleman conducting the interview doesn't seem to understand anything about astronomy, such as the difference between a planet and a star.