Early Astronomy, Seasons, Solstices, and Equinoxes

Vocabulary flashcards covering early astronomy, Earth's axial tilt, celestial geometry, equinoxes, and solstices from lecture slides.

Finding Direction (Ancient Astronomy)

A primary practical reason ancient cultures developed basic astronomy, essential for travel and communication.

Keeping Time (Ancient Astronomy)

A practical application of astronomy used by ancient cultures to establish times to sow and harvest crops, gather wild fruits, and hunt game on seasonal migrations.

Ritualistic Reasons (Ancient Astronomy)

The practice in ancient cultures of associating natural phenomena (such as earthquakes) with astronomical events in the absence of scientific theories.

Celestial Sphere

An astronomical concept created by projecting the Earth's equator and poles into space.

Earth's Axial Tilt

The tilt of Earth's axis of rotation, which is $23.5^\circ$ away from the direction perpendicular to Earth's orbital plane.

North Star

The star toward which the Earth's North Pole is always tilted.

Directness of Sunlight

The angle at which the Sun's rays strike the surface of Earth, which has the biggest impact on weather.

Equinox

The event occurring when the Sun is at the points in space where the ecliptic and celestial equator intersect, resulting in day and night each being $12\text{ hours}$ long everywhere on Earth.

Solstice

The event occurring when the Sun reaches its most northern and southern points in the sky.

Vernal Equinox

An equinox that occurs on March 21.

Autumnal Equinox

An equinox that occurs on September 21.

Summer Solstice

Occurs on June 21 in the northern hemisphere, when the Sun rises at its northernmost point, producing longer days in the northern hemisphere.

Winter Solstice

Occurs on December 21 in the northern hemisphere, when the Sun rises at its southernmost point.