Five questions added to my Q&A page this week, bringing the total to a nice round 50.
1) What happens to galaxies after their central black holes evaporate ?
Nothing, because all their stars will be dead and black holes just aren't that big anyway.
2) If space and time are expanding, how can we estimate the age of the Universe ?
3) How do we know the distances to the stars ?
By drawing big triangles IIIIIINNNNN SPPPPAAAAAACE !
4) Will our Solar System suffer from a space tidal wave ?
5) What's the difference between gravitational waves and tidal forces ?
Waves move. Tidal forces are lazier.