Nectarine trees produce varietals of fruit that commonly have smooth skin, firm flesh and a stone that either removes easily from the flesh or clings to it, giving them further classification as clingstone or freestone.
The ecliptic is an imaginary line that marks the path of the sun. The signs of the Zodiac come from the constellations that lie along this line. As Earth orbits the sun, the sun appears to drift across the background stars. The ecliptic marks out the path of this motion on the sky.
A circle is a closed curved shape that is flat. That is, it exists in two dimensions or on a plane. In a circle, all points on the circle are equally far from the center of the circle. An ellipse is also a closed curved shape that is flat. Instead of having all points the same distance from the center point, though, an ellipse is shaped so that when you add together the distances from two points inside the ellipse (called the foci) they always add up to the same number.