Earth Science: Shape and Movements

Study Notes

Shape of the Earth

The Earth is not perfectly spherical, it is an oblate spheroid, meaning it is flattened at the poles.
The Earth's surface is not smooth, it is represented by the geoid which accounts for the irregularities.
The shape of the Earth was first believed to be spherical by Aristotle.

Size of the Earth

The Earth’s radius is approximately 6,378.245 km.
The equatorial circumference measures approximately 40,075 km.
The surface area of the Earth is approximately 510 million km².

Earth's Movements

The Earth revolves around the Sun in an elliptical orbit.
During its orbit, the Earth reaches its furthest point from the Sun, known as aphelion, and moves slower.
The Earth also reaches its closest point to the Sun, known as perihelion, and moves faster.
The Earth's average orbital speed is approximately 29.76 km/s.
One complete orbit of the Earth around the Sun takes approximately 365 days, 5 hours, 48 minutes, and 45.7 seconds, known as a tropical year.
Different points of the Earth’s orbit result in varying seasons due to the Earth’s axial tilt.
The Earth rotates on its own axis.
The Earth’s axial tilt is 66.5° relative to the plane of its orbit.
The Earth completes one rotation on its axis in approximately 23 hours, 56 minutes, and 4 seconds, known as a sidereal day.
From the perspective of the Sun, the Earth completes one rotation in 24 hours, known as a solar day.

Consequences of Earth's Movements

The change of seasons is due to the axial tilt, which results in differing amounts of sunlight received by various latitudes throughout the year.
The length of the polar day varies due to the axial tilt.

Description

Explore the intriguing shape and movements of the Earth in this quiz. Learn about the Earth's oblate spheroid form, its size metrics, and the dynamics of its orbit around the Sun. Test your knowledge about Earth's unique characteristics and celestial motions.