Complete the following sentences about our Solar System and the wider Universe:

1. The shape of the orbit of a comet around a star is highly \text{________________}.
2. Two planets in our Solar System that do not have any natural satellites (moons) are \text{________________} and \text{________________}.
3. A large collection of billions of galaxies is referred to as the \text{________________}.

The diagram shows the highly elliptical orbit of a comet as it moves around a star. $A$, $B$, $C$, and $D$ are points along its orbital path.

Draw on this

At which of the points shown is the orbital speed of the comet greatest?

At which of the points shown is the gravitational pull on the comet the weakest?

At which of the points shown is the gravitational potential energy of the comet at its minimum?

State the direction of the gravitational force acting on the comet when it is at point $B$.