What shape of the planets orbit?
The planets orbit in an ellipse. An ellipse is described as a
geometric shape where the sum of the distance from the foci at any
point is the same. An ellipse has three main points. Two foci and a
center like a circle. While a true circle has all its external
points equidistant from its center, an ellipse measures its points
from the foci, which are equidistant to the center point at on both
sides.
The planets ellipse is closer to a circle than an all out
ellipse, however, the orbit is still a true ellipse.
It is also true that the shape of a planet's orbit (an ellipse)
is a conic section, i.e. the intersection of a right circular cone
where the intersecting plane is not perpendicular to the cone's
axis, but less than being parallel to one of the cone's nappes.