PV Gap

Roy Said:

Is the sun actually stationary? Or the whole solar system also moves within the galaxy?

We Answered:

If the sun were stationary it would be the center of the universe.

Most theories accept that the sun (and the solar system) moves relative to the center of our galaxy, and our galaxy moves relative to other galaxies.

But, of course, we know the universe moves around Paris Hilton...

Katherine Said:

Can a comet orbiting the Sun reach the solar system's escape velocity?

We Answered:

Yes, any comet in a parabolic or hyperbolic orbit has the escape velocity.

# Parabolic orbit: An orbit with the eccentricity equal to 1. Such an orbit also has a velocity equal to the escape velocity and therefore will escape the gravitational pull of the planet.

# Hyperbolic orbit: An orbit with the eccentricity greater than 1. Such an orbit also has a velocity in excess of the escape velocity and as such, will escape the gravitational pull of the planet and continue to travel infinitely.