Earth has seasons because

a.
it rotates on its axis.

b.
the distance between earth and the sun changes.

c.
its axis is tilted as it moves around the sun.

d.
the temperature of the sun changes.

The Earth has seasons because its axis is tilted and not straight up and down compared to the orbit. The seasons have nothing to do with the distance to the Sun or with the sun's temperature or with the Earth's rotation. We are closest to the Sun in early January. We are farthest from the Sun in early July.

Kinetic energy = 1/2mv^2. since the mass is constant we can form a ratio of it's kinetic energy at 60 divided by that at 30 to see ke(60)/ke(30) = +(60^2)/30^2). this may be said to 300% increase.