Final answer:
The two lengths that all elliptical orbits have are the major axis and the semimajor axis.
Step-by-step explanation:
The two lengths that all elliptical orbits have are the major axis and the semimajor axis.
The major axis is the widest diameter of the ellipse, which is the longer axis.
The semimajor axis is half the major axis, and it represents the distance from the center of the ellipse to one end. It is commonly used to specify the size of the ellipse.
For example, the semimajor axis of Mars' orbit, which also represents the planet's average distance from the Sun, is 228 million kilometers.