What would happen if you fired a sniper bullet horizontally from the top of Ahuna Mons, the highest mountain of Ceres? Once I read somewhere that if you fired a bullet on the Moon in the correct angle, it could land on the other side of the Moon. If that's true, on Ceres with 0.00016 Earth masses and 0.029 the Earth's surface gravity a bullet surely could enter an orbit around Ceres if fired from Ahuna Mons, or even escape velocity if fired in the correct angle, or not?

Ceres' escape velocity is about 510 m/s (about 1670 ft/s). I think that's achievable by certain guns.

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    $\begingroup$ It doesn't matter whether you fire horizontally. Escape velocity is independent of the angle, although of course you can't aim below horizontal. $\endgroup$
    – user687
    Jul 7 '20 at 15:45
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    $\begingroup$ To reach an orbit from the surface of Ceres using a firearm is impossible, The bullet would crash into the surface after one revolution. You need a sufficient height for a stable orbit due to the irregular shape of Ceres. For very low orbits you need a celestical body with a perfect spherical shape and symmetrical density. $\endgroup$
    – Uwe
    Jul 7 '20 at 16:16
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    $\begingroup$ @Uwe This is why I wrote "horizontally from the top of Ahuna Mons". Like this, it would achieve an orbit unless it reaches escape velocity. Ahuna Mons is a lonely mountain. $\endgroup$ Jul 7 '20 at 16:37
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    $\begingroup$ @Uwe By shooting the bullet arbitrarily close to escape velocity, you can make the period arbitrarily long, the mean orbital height arbitrarily large, and the time spent in low orbit an arbitrarily small fraction of the period. Shooting from the ground only constitutes a "low orbit" if you fire with low enough velocity to have a circular orbit. Is an arbitrarily large orbit around a non-uniform body also inherently unstable? $\endgroup$ Jul 7 '20 at 20:57
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    $\begingroup$ Quite a few guns, not just sniper rifles, could hit the required velocity. Hell, even an FN P90 could do it (muzzle velocities are about 200 m/s higher than what's needed, and there's no air resistance to slow the bullet down), let alone most rifle cartridges and even some handguns (I'd actually be surprised if anything using a modern intermediate cartridge such as 5.56x45mm or 5.45x69mm couldn't do it, provided of course that it wasn't a subsonic load). $\endgroup$ Jul 8 '20 at 2:05

Indeed, you are correct, it could reach escape velocity. The M110 can reach speeds of over 700 m/s, which is well above the escape velocity. Most guns actually don't need oxygen to work either, as the gun powder has the oxygen needed. So yeah, be extra careful where you fire a gun on an asteroid.

  • $\begingroup$ @uhoh There r many planetary moons you have to be careful on too: all Saturnian moons except Titan, all Uranian moons, Pluto's moon Charon and Eris' moon Dysnomia. Maybe you need to be careful on Europa too since it is less massive than the Moon and has a weaker surface gravity than the Moon. Probably not on Triton, Eris or Pluto because they have considerable atmospheres. $\endgroup$ Jul 7 '20 at 12:44
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    $\begingroup$ Added the word "extra". $\endgroup$
    – PearsonArtPhoto
    Jul 7 '20 at 13:18
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    $\begingroup$ Obligatory "Men of Good Will" reference: books.google.com/… $\endgroup$ Jul 7 '20 at 13:21
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    $\begingroup$ That's like Ford Prefect getting Earth's description changed to 'Mostly Harmless' @PearsonArtPhoto $\endgroup$
    – GdD
    Jul 7 '20 at 15:22
  • $\begingroup$ en.wikipedia.org/wiki/Newton%27s_cannonball $\endgroup$
    – uhoh
    Jul 7 '20 at 19:39

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