Astronomical Distances Vocabulary

the average distance between the Earth and the Sun

the trajectory followed by an object revolving around another object under the influence of gravity

a number between 0 and 1 that describes the shape of an ellipse

the point in its orbit where a planet (or comet) is nearest the Sun

the point in its orbit where a planet is farthest from the Sun

the time, in years, for one revolution of a planet around the sun

a method of writing numbers in terms of a decimal number between 1 and 10 multiplied by a power of 10

a method of writing numbers without being multiplied by a power of 10

the distance light travels in a vacuum (i.e. empty space) in 1 year

the apparent displacement of a star due to Earth's motion around the Sun