# Does black hole have the following properties? [closed]

1. Black holes emit x-rays lights from within their event horizons (I believe this one is unknown because you cannot see what's going on inside event horizon)

2. A 9 km black hole may be hidden between Saturn and Jupiter (I think it's true because the distance between these planets are larger than 9km).

3. A black hole in a binary system will suck in its companion (Not sure about this one because I don't think the effect is large in a non-close binary system)

4. Singularity of black hole has infinite density (I guess it is true but can't find evidence)

Could someone give any suggestion, please?

## closed as too broad by Rob Jeffries, Sir Cumference, Hohmannfan, Andy, called2voyage♦Nov 21 '16 at 14:58

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

• Appears to be homework question. – Rob Jeffries Nov 20 '16 at 11:06
• I'm voting to close this question as off-topic because this looks like someone's homework. – Rob Jeffries Nov 20 '16 at 20:14
• Though it’s interesting to read his thoughts annotated to each question. This shows that what he really needs is a deeper understanding of the particulars. – JDługosz Nov 20 '16 at 20:16
• I agree with @JDługosz that the annotations are interesting, those cause this to be a higher quality question than the usual homework questions. It is still not good, but a small thing like that helps me to keep my faith in humanity. – Hohmannfan Nov 20 '16 at 23:30

2. A 9km black hole could not lie within the solar system without disrupting the orbits of nearby planets. A black hole 9km across would have to be about 3 times more massive than our sun. You can calculate this by using a simplification of the formula for the Schwarzschild Radius: $r\approx 2.95 \frac{M}{M_{\odot}}$. If this were the case, then the orbital motions of the planets would be dominated more by this black hole than by the sun.