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CPG Grey, Which Planet is the Closest?: https://www.youtube.com/watch?v=SumDHcnCRuU https://www.youtube.com/watch?v=SumDHcnCRuU

Blammar 3y ago
The most surprising conclusion is that Mercury is on the average closest to ANYTHING that orbits the sun, including (presumably) long-orbit comets!
- yreg 3y ago
  It's totally unintuitive, but makes perfect sense once you know the answer.
- orlp 3y ago
  This isn't true for two different objects in the same orbit with a small phase difference. To be fair that arrangement is rather unstable, especially with planet-sized objects.
- mr_toad 3y ago
  The whirly dirly corollary. talk about cosmic apotheosis.
m348e912 3y ago
Doesn't this also imply that the sun is mostest closest to any planet than any other planet?
- ithkuil 3y ago
  I had the same thought: if there was another planet inside mercury's orbit, that would be the mostest closest planet to all the planets, stealing mercury's status, and so you keep iterating on that until you reach smallest and smallest orbits around the sun center of mass (which is inside the sun). So, if you when you say "the sun" you mean the sun surface, then yes, the sun is always the mostest closest celestial body, to all planets
  - manojlds 3y ago
    Why do you complicate it talking of surface vs center of sun. Sun is sun. That's it.
    - ithkuil 3y ago
      just because it made it easier for me to reason about the fact that since the sun has some actual width it's exactly equivalent to a body that would orbit at that distance. If you frame it that way then it's rather obvious that the sun also fits the bill as the "mostest closest body" (albeit not planet)
      - hgsgm 3y ago
        The center of the sun has the same property, with simpler 0 size orbit.
        ithkuil 3y ago
        it's not intuitively clear to me whether that is on average closer to the earth or if it's on average exactly as far as something orbiting around that center. Furthermore, since the sun is also orbiting around the shared center of mass of the whole solar system, this displacement albeit very small, is still enough for me to not intuitively understand if it makes the sun's center of mass closer or farther away on average than the closest orbiting body to the sun
- tromp 3y ago
  Yes, a hypothetical planet located at the centre of the sun would be every planet's closest neighbour, by virtue of never getting as far away as others.
  - sjcsjc 3y ago
    The concept of a hypothetical planet at the centre of the sun made me laugh. Cheers
    - hibbelig 3y ago
      I don't understand why we need to introduce this planet. Is the Sun not our neighbor? And it's closer than Mercury, isn't it?
      - hgsgm 3y ago
        Other posters seem to be treating planets as point masses but not the sun.
      - input_sh 3y ago
        > Is the Sun not our neighbor? And it's closer than Mercury, isn't it? It's not half the time and it is half the time. If you include the Sun as well as one of the possible answers (which I'd argue you shouldn't because neighbour implies same significance, not higher), the answer would've been an even split between Mercury and the Sun (on a large enough time scale). If Mercury's year somehow lasted longer than a year on another planet, only then would Sun be the clear winner.
        SamBam 3y ago
        Actually the sun still edges out Mercury. Think of it this way: If we take the Earth as stationary and just look at the respective motions of the Sun and Mercury, then the Sun is also (roughly) stationary* and Mercury moves around and around it, sometimes close to us and sometimes far. Now, if Mercury actually yo-yo'ed through the Sun, then you'd be right: exactly half the time it would be closer to us, and half the time it would be further from us. But it doesn't yo-yo through the Sun, it moves in a circle. When it's 90º from us and the Sun, it's still further away from us than the Sun is. So it has to get even closer before it's equidistant. So it's actually closer to us only less than half of the time. *Yes, the Sun would also appear to orbit around the gravitational center of mass, but this doesn't affect the thinking above.
8note 3y ago
"Closest the mostest" makes it feel like less of a gotcha

Blammar 3y ago

The most surprising conclusion is that Mercury is on the average closest to ANYTHING that orbits the sun, including (presumably) long-orbit comets!

yreg 3y ago
It's totally unintuitive, but makes perfect sense once you know the answer.
orlp 3y ago
This isn't true for two different objects in the same orbit with a small phase difference. To be fair that arrangement is rather unstable, especially with planet-sized objects.
mr_toad 3y ago
The whirly dirly corollary. talk about cosmic apotheosis.

m348e912 3y ago

Doesn't this also imply that the sun is mostest closest to any planet than any other planet?

ithkuil 3y ago
I had the same thought: if there was another planet inside mercury's orbit, that would be the mostest closest planet to all the planets, stealing mercury's status, and so you keep iterating on that until you reach smallest and smallest orbits around the sun center of mass (which is inside the sun). So, if you when you say "the sun" you mean the sun surface, then yes, the sun is always the mostest closest celestial body, to all planets
- manojlds 3y ago
  Why do you complicate it talking of surface vs center of sun. Sun is sun. That's it.
  - ithkuil 3y ago
    just because it made it easier for me to reason about the fact that since the sun has some actual width it's exactly equivalent to a body that would orbit at that distance. If you frame it that way then it's rather obvious that the sun also fits the bill as the "mostest closest body" (albeit not planet)
    - hgsgm 3y ago
      The center of the sun has the same property, with simpler 0 size orbit.
      - ithkuil 3y ago
        it's not intuitively clear to me whether that is on average closer to the earth or if it's on average exactly as far as something orbiting around that center. Furthermore, since the sun is also orbiting around the shared center of mass of the whole solar system, this displacement albeit very small, is still enough for me to not intuitively understand if it makes the sun's center of mass closer or farther away on average than the closest orbiting body to the sun
tromp 3y ago
Yes, a hypothetical planet located at the centre of the sun would be every planet's closest neighbour, by virtue of never getting as far away as others.
- sjcsjc 3y ago
  The concept of a hypothetical planet at the centre of the sun made me laugh. Cheers
  - hibbelig 3y ago
    I don't understand why we need to introduce this planet. Is the Sun not our neighbor? And it's closer than Mercury, isn't it?
    - hgsgm 3y ago
      Other posters seem to be treating planets as point masses but not the sun.
    - input_sh 3y ago
      > Is the Sun not our neighbor? And it's closer than Mercury, isn't it? It's not half the time and it is half the time. If you include the Sun as well as one of the possible answers (which I'd argue you shouldn't because neighbour implies same significance, not higher), the answer would've been an even split between Mercury and the Sun (on a large enough time scale). If Mercury's year somehow lasted longer than a year on another planet, only then would Sun be the clear winner.
      - SamBam 3y ago
        Actually the sun still edges out Mercury. Think of it this way: If we take the Earth as stationary and just look at the respective motions of the Sun and Mercury, then the Sun is also (roughly) stationary* and Mercury moves around and around it, sometimes close to us and sometimes far. Now, if Mercury actually yo-yo'ed through the Sun, then you'd be right: exactly half the time it would be closer to us, and half the time it would be further from us. But it doesn't yo-yo through the Sun, it moves in a circle. When it's 90º from us and the Sun, it's still further away from us than the Sun is. So it has to get even closer before it's equidistant. So it's actually closer to us only less than half of the time. *Yes, the Sun would also appear to orbit around the gravitational center of mass, but this doesn't affect the thinking above.

8note 3y ago

"Closest the mostest" makes it feel like less of a gotcha