it the sun
The low density of Saturn would allow it to float in liquid water.
Two or three planets align from time to time, but an alignment of all the planets would never happen.
No. The outer planets do not have solid surfaces. Those planets are made of gases held together by gravity.
There probably couldn't, though if an astrophysicist wants to correct this feel free. The problem is that gas molecules have high velocities. If the mass of the body is high enough to have an...