Video Notes: Earth's Rotation, Revolution, and Orbital Plane

Vocabulary flashcards covering key terms from the lecture notes on Earth’s rotation, revolution, and orbital plane.

Celestial object

An object in space such as the Sun, Moon, stars, or planets.

Rotation

The spinning of Earth around its axis, causing day and night.

Axis

The imaginary line through which a body rotates; for Earth it connects the North and South Poles.

Polaris (North Star)

A bright star near the North Pole that appears to be the center around which circumpolar stars move.

Star trails

The apparent circular paths of stars around Polaris caused by Earth's rotation.

Sun's apparent motion

The Sun appears to rise in the east and set in the west because of Earth's rotation.

Orbit

The path a celestial body follows around another body in space; Earth orbits the Sun.

Revolution

The movement of a body around another body in space; Earth’s year-long orbit around the Sun.

Ellipse

An oval-shaped path; the general shape of most orbits; Earth’s orbit is almost circular.

Seasonal stars

Stars that are visible only during part of the year due to Earth's revolution.

Orion

A seasonal constellation visible in winter in the Northern Hemisphere.

Scorpius

A seasonal constellation whose stars rise and set over several months.

Circumpolar stars

Stars located above and around the poles and visible all year round.

Earth's orbital plane

The flat plane in which Earth orbits the Sun.

Sun on Earth's orbital plane

The Sun lies on or near Earth’s orbital plane, affecting star visibility.

Circumpolar visibility

Circumpolar stars are never drowned out by the Sun and are visible year-round.

North Pole

The northern end of Earth's axis; Polaris is near this location.

South Pole

The southern end of Earth's axis; circumpolar stars near the South Pole are not visible from the Northern Hemisphere.

Polaris’ relation to the North Pole

Polaris is located near the North Pole and is not visible from the South Pole.

Fixed stars

Stars with fixed positions in space; their apparent motion comes from Earth's movements.

Daytime visibility vs. nighttime visibility

Some stars are visible only at night because the Sun’s light drowns them out during the day.

Drowning out by the Sun

The Sun’s brightness makes it impossible to see certain stars during daytime.

Winter and Summer stars

Seasonal stars such as Orion (winter) and Scorpius (summer) seen at different times of year.

Direction of star visibility changes

As Earth orbits the Sun, different regions of space become visible at night.

Concentric circles

Circular star trails around Polaris created by Earth’s rotation.