Astronomical Terms Quiz

Astronomical Terms

• Astronomical Unit (AU): The average distance between Earth and the Sun, approximately 1.5 x 10⁸ kilometers or 1.5 x 10¹¹ meters.
• Eccentricity: In an ellipse, the ratio of the distance between the foci to the major axis.
• Ellipse: A closed curve where the sum of the distances from any point on the ellipse to two fixed points (foci) inside the ellipse is constant.
• Focus: One of two fixed points inside an ellipse. The sum of the distances to any point on the ellipse from the two foci is constant.
• Kepler's First Law: Each planet orbits the Sun in an elliptical path, with the Sun at one focus of the ellipse.
• Kepler's Second Law: A line joining a planet and the Sun sweeps out equal areas in space during equal intervals of time.
• Kepler's Third Law: The square of a planet's orbital period is directly proportional to the cube of the semimajor axis of its orbit.
• Orbit: The path of an object revolving around another object.
• Orbital Period (P): The time it takes an object to complete one orbit around another.
• Orbital Speed: The speed at which an object travels along its orbit.
• Semimajor Axis: Half of the major axis of an ellipse.