Geography & Astronomy Notes (Pages 1-3): Earth Shape, Time, Tides

Vocabulary flashcards covering key terms from pages on lunar eclipses, Earth’s shape, timekeeping, tides, and geodesy.

Earth's shadow during a lunar eclipse

The Earth's shadow cast on the Moon; it appears circular.

Equator

The largest circle of latitude on Earth, dividing it into Northern and Southern Hemispheres.

Global Positioning System (GPS)

A satellite-based system used to determine precise position and time anywhere on Earth.

Five oceans

There are five oceans on Earth: Pacific, Atlantic, Indian, Arctic, and Southern.

Gravity

The gravitational force that shapes Earth and governs motion; the main force influencing Earth's form.

Tides

Regular movements of sea level caused mainly by the Moon's gravitational pull.

Main cause of tides

The Moon's gravitational attraction on Earth's oceans (with the Sun contributing to a lesser extent).

Magellan's circumnavigation

The voyage that circumnavigated the Earth, providing evidence of its sphericity.

Prime Meridian

0° longitude line through Greenwich; reference for time zones and longitude.

Longitude

Imaginary lines running from the North to the South Pole; 360° around the globe.

Centrifugal force

An apparent force that arises in a rotating frame of reference; explains the Earth’s equatorial bulge.

Taiga

A boreal forest zone in the Northern Hemisphere, dominated by coniferous trees.

Eratosthenes method

The ancient method of estimating Earth’s circumference by comparing shadows at different locations.

Geoid

The Earth's real shape, defined by mean sea level and irregularities in topography.

Rotationsellipsoid (rotational ellipsoid)

A mathematical ellipsoid of revolution used to approximate Earth's shape.

Atmospheric pressure

Air pressure; it does not determine Earth's overall shape.

0° longitude / Prime Meridian origin

The origin for measuring longitude; divides East and West hemispheres.

360 degrees of longitude

The total angular measure around the Earth along meridians; 360° corresponds to a full circle.