8th Vocab. Planetary Characteristics

Front

What is the mass of a planet measured in?

Back

The mass of a planet is measured in septillion (1 followed by 24 zeros) kilograms or sextillion (1 followed by 21 zeros) tons.

Front

How is the diameter of a planet defined?

Back

The diameter of a planet is the distance through the center of the planet from one point on the equator to the opposite side, measured in kilometers or miles.

Front

What is density and how is it measured for planets?

Back

Density is the average mass divided by volume of the whole planet, measured in kilograms per cubic meter or pounds per cubic foot.

Front

How is gravity on a planet's surface measured?

Back

Gravity is the gravitational acceleration on the surface at the equator, measured in meters per second squared or feet per second squared.

Front

What is escape velocity?

Back

Escape velocity is the initial velocity needed at the surface to escape the body's gravitational pull, measured in kilometers per second.

Front

What does rotation period refer to?

Back

Rotation period is the time it takes for the planet to complete one rotation relative to the fixed background stars, measured in hours.

Front

What is the length of a day on a planet?

Back

The length of a day is the average time for the Sun to move from the noon position in the sky at a point on the equator back to the same position, measured in hours.

Front

How is the distance from the Sun measured?

Back

The distance from the Sun is the average distance from the planet to the Sun, measured in millions of kilometers or miles.

Front

What are perihelion and aphelion?

Back

Perihelion is the closest point and aphelion is the furthest point in a planet's orbit about the Sun.

Front

What is orbital period?

Back

Orbital period is the time in Earth days for a planet to orbit the Sun from one vernal equinox to the next.