[quote=whizzball1]
Okay, so after redoing the calculations, the Schwarzschild Radius for a sphere of pure water of diameter 55000 light years is 1.14^10^38 metres. The radius of such a sphere in metres would be 5.203 * 10^20 metres, which actually is less than the Schwarzschild radius. However, we can switch this out for earth, which has a solid density of 5515 kg/m^3.The mass of this planet would be 4.06823×10^65 kg.The Schwarzschild Radius for this planet would be 6.041×10^38 meters...? Which is apparently more than the Radius for water even though Earth is far more dense... So never mind about the planet collapsing in on itself and becoming a black hole.
[/quote]

Wait wait wait I messed up. It turns out that the Radius is what the sphere must fall [i]under[/i], not above. So, yeah, the planet should be collapsing into a black hole right now. And there's no way to stop it unless you could somehow negate the immense gravitational pull preventing light from escaping.