Kepler's 1st law review

Study review for Honors Integrated Science

Aphelion

The point in an orbit where an object is farthest from the sun. Happens in July

perihelion

The point in an orbit where an object is closest to the sun. Happens in January.

Geocentric model of the solar system

An astronomical model where the Earth is at the center of the universe, and all other celestial bodies orbit around it.

Heliocentric model of the solar system

A model in which the sun is at the center of the solar system, Earth, other planets, and moons orbiting around it.

Ellipse

A closed curve shape that is elongated in one direction, representing the path of planets as they orbit the sun according to Kepler's first law.

An Oval shape with 2 foci that may appear circular.

True circle

A geometric shape where all points are equidistant from the center, representing a special case of an ellipse with equal foci.

Focus

1 point at the center of a true circle.

Foci (Plural)

The two points located along the major axis of an ellipse, equal distance from the center, determine the shape of the ellipse.

Focal Length

The distance between 2 foci in an ellipse.

Major Axis

The longest diameter of an ellipse, passing through both foci and the center, defining the overall shape and size of the ellipse.

Major= longer diameter, minor=shorter diameter

Eccentricity

A ratio describing an ellipse’s flatness or smoothness. Value between 0 and 1.

Eccentricity=focal length divided by length of major axis.

Eccentricity of true circle = 0

Eccentricity of a line = 1