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When does a planet move fastest in its orbit?

Back

A planet moves fastest in its orbit when it is closest to the sun (perihelion).

Front

What defines the radius of a celestial body?

Back

The radius of a celestial body is defined as the distance from its center to its surface.

Front

What does analogous mean in planetary science?

Back

In planetary science, analogous means having similar environmental conditions.

Front

When does Earth reach its perihelion?

Back

Earth reaches its perihelion around January 4.

Front

What is the maximum distance (in AU) that comets in the Oort cloud can be from the sun?

Back

The maximum distance that comets in the Oort cloud can be from the sun is 200,000 AU.

Front

What is perihelion?

Back

Perihelion is the point in the orbit of a planet where it is closest to the sun.

Front

What is aphelion?

Back

Aphelion is the point in the orbit of a planet where it is farthest from the sun.

Front

What is the significance of the Oort cloud?

Back

The Oort cloud is a theoretical cloud of icy bodies that is believed to be the source of long-period comets.

Front

What is an astronomical unit (AU)?

Back

An astronomical unit (AU) is the average distance from the Earth to the Sun, approximately 93 million miles or 150 million kilometers.

Front

What is the difference between a planet and a dwarf planet?

Back

A planet is a celestial body that orbits the sun and has cleared its orbit of other debris, while a dwarf planet is similar but has not cleared its orbit.