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If we’re talking about the known universe, the odds of your near-light navigation accidentally clipping a not-mapped-yet planet are certainly not zero. Our gaz

If we’re talking about the known universe, the odds of your near-light navigation accidentally clipping a not-mapped-yet planet are certainly not zero. Our gaze into the heavens is much better at spotting stars than their dark orbiting bodies, and we have fingers left over from one hand counting the number of observation platforms observing deep space from above our shimmering atmosphere.

eru 3y ago
It doesn't matter whether we can see those dark orbiting bodies: we observe minuscule gravitational impact on the stars, and that places a very sharp upper limit on the amount of mass that's outside of the star in a solar system. The sun contains roughly 99.8% of the mass of the solar system, and is by far the largest object in it. But you wouldn't hit the sun randomly either. Space is just so damn large.
StevePerkins 3y ago
Indeed. We can't even agree on whether or not there's an extra Neptune-sized gas giant out beyond the orbit of Pluto, and that's right here in our OWN solar system!
- eru 3y ago
  So? Even ten extra Jupiters or thousand extra suns would take up only a tiny amount of space compared to the size of the solar system out to Pluto: The distance from the sun to Pluto is about 5.9 billion km. The radius of the sun is about 696,340 km. The ratio of radii is about 8,473. Cube that to get the ratio of volumes, and you get 608,263,848,559 for the ratio of volume in a sphere out to Pluto vs volume of the sun. (Doing the numbers, I'm actually surprised: I had expected the ratio of radii to be bigger than 8,473. But I'm not surprised that the sun barely takes up any space.)
  - denton-scratch 3y ago
    > The radius of the sun is about 696,340 km Arguably, the entire heliosphere is part of the Sun's atmosphere, and it reaches well beyond Pluto. If I were in a relativistic spaceship, I think I'd want to apply the brakes well before slamming into the heliosphere. What do you call the heliosphere of a star that isn't the Sun? The stellosphere?
    - denton-scratch 3y ago
      Replying to self (sorry). "Stellosphere" is wrong, because "stella" is Latin, and "sphere" is from Greek. It should be "asterosphere", but that's a word I've never seen nor heard.
      - eru 3y ago
        We have been mixing up Latin and Greek for quite a few terms already, so I don't think that should keep you from using a term.
Dylan16807 3y ago
> If we’re talking about the known universe, the odds of your near-light navigation accidentally clipping a not-mapped-yet planet are certainly not zero. If we're still talking about Star Trek, then on a solar scale those ships can stop on a dime. They're not going to hit an unmapped planet while putting around.

eru 3y ago

It doesn't matter whether we can see those dark orbiting bodies: we observe minuscule gravitational impact on the stars, and that places a very sharp upper limit on the amount of mass that's outside of the star in a solar system. The sun contains roughly 99.8% of the mass of the solar system, and is by far the largest object in it. But you wouldn't hit the sun randomly either. Space is just so damn large.

StevePerkins 3y ago

Indeed. We can't even agree on whether or not there's an extra Neptune-sized gas giant out beyond the orbit of Pluto, and that's right here in our OWN solar system!

eru 3y ago
So? Even ten extra Jupiters or thousand extra suns would take up only a tiny amount of space compared to the size of the solar system out to Pluto: The distance from the sun to Pluto is about 5.9 billion km. The radius of the sun is about 696,340 km. The ratio of radii is about 8,473. Cube that to get the ratio of volumes, and you get 608,263,848,559 for the ratio of volume in a sphere out to Pluto vs volume of the sun. (Doing the numbers, I'm actually surprised: I had expected the ratio of radii to be bigger than 8,473. But I'm not surprised that the sun barely takes up any space.)
- denton-scratch 3y ago
  > The radius of the sun is about 696,340 km Arguably, the entire heliosphere is part of the Sun's atmosphere, and it reaches well beyond Pluto. If I were in a relativistic spaceship, I think I'd want to apply the brakes well before slamming into the heliosphere. What do you call the heliosphere of a star that isn't the Sun? The stellosphere?
  - denton-scratch 3y ago
    Replying to self (sorry). "Stellosphere" is wrong, because "stella" is Latin, and "sphere" is from Greek. It should be "asterosphere", but that's a word I've never seen nor heard.
    - eru 3y ago
      We have been mixing up Latin and Greek for quite a few terms already, so I don't think that should keep you from using a term.

Dylan16807 3y ago

> If we’re talking about the known universe, the odds of your near-light navigation accidentally clipping a not-mapped-yet planet are certainly not zero. If we're still talking about Star Trek, then on a solar scale those ships can stop on a dime. They're not going to hit an unmapped planet while putting around.