element: A substance that cannot be chemically broken down into another substance is known as an element. All the atoms in an element are the same kind. There are over 100 known elements, including iron, oxygen, gold, copper, and carbon. All matter in the universe is made from combinations of these 100 elements. The most common elements in the universe are hydrogen and helium. It is generally believed that 98% of the universe's matter consists of these two simple elements.
ellipse: An ellipse is a geometric shape. It looks like an oval or a flattened circle. An ellipse can be very close to the shape of a circle, or it can be very long and narrow, or it can be anywhere in between. In the early 17th century, Johannes Kepler realized that the shape of every planet's orbit was an ellipse.
