Earth's Movements, Solstices, and Spherical Evidence

Vocabulary flashcards covering Earth's rotation, revolution, solstices, orbit, oblate spheroid shape, and scientific evidence for Earth's spherical shape.

Rotation of Earth

The spinning of the Earth on its axis from west to east, where one complete rotation takes $24\,\text{hours}$ (one day).

Day and Night

The daily cycle caused by Earth's rotation, where the side of Earth facing the Sun experiences day and the side turned away experiences night.

Solstice

An astronomical event that occurs when the Sun is directly overhead at either the Tropic of Cancer ($23\frac{1}{2}^\circ\,\text{N}$) or the Tropic of Capricorn ($23\frac{1}{2}^\circ\,\text{S}$).

Tropic of Cancer

The line of latitude at $23\frac{1}{2}^\circ\,\text{N}$ where the Sun is directly overhead during the solstice on about June 21.

Tropic of Capricorn

The line of latitude at $23\frac{1}{2}^\circ\,\text{S}$ where the Sun is directly overhead during the solstice on about December 22.

June (Summer) Solstice

The solstice associated with the Northern Hemisphere when the Sun is directly overhead at the Tropic of Cancer ($23\frac{1}{2}^\circ\,\text{N}$).

Revolution of Earth

The movement of the Earth around the Sun, taking $365\frac{1}{4}\,\text{days}$ (about one year) to complete one cycle.

Orbit

The slightly oval path taken by the Earth during its revolution around the Sun.

Seasons

The recurring annual weather patterns produced by Earth's revolution around the Sun together with its axial tilt.

Oblate Spheroid

The term for Earth's approximate ball shape, which is slightly flattened at the poles and bulges slightly at the Equator.

Circumnavigation

Travelling completely around the Earth and eventually reaching towards the starting point, serving as evidence of Earth's spherical shape.

Sinking Ships Evidence

Evidence for Earth's roundness shown when ships sailing away have their hulls disappear before their masts, proving travel over a downward curve.

Lunar Eclipse Shadow Evidence

Evidence of Earth's spherical shape seen when Earth passes directly between the Sun and Moon, casting a shadow on the Moon's surface that is always perfectly round or circular.

Changing Star Constellations Evidence

Evidence for a curved Earth surface where visible night sky stars change as one travels north or south, such as the North Star dropping lower as one moves south.

Satellites Evidence

Spacecraft instruments used to take photographic evidence showing the Earth as a sphere.

Different Sunrise and Sunset Times

An observational effect supporting Earth's spherical shape based on sunrise and sunset occurring at different times in different regions.