Astronomy Unit Overview

A series of vocabulary flashcards based on key terms and concepts from the Astronomy Unit.

Meteor

A small solid particle from space that enters the Earth's atmosphere and becomes visible as a streak of light.

Meteoroid

A smaller object in space that can become a meteor when it enters the Earth's atmosphere.

Meteorite

A meteoroid that survives its passage through the atmosphere and lands on the Earth's surface.

Light year

The distance that light travels in one year, approximately 9.46 imes 10^{12} kilometers.

Far side of the Moon

The hemisphere of the Moon that is always facing away from the Earth.

Near side of the Moon

The hemisphere of the Moon that is always facing the Earth.

Dark side of the Moon

Commonly refers to the far side of the Moon, not receiving sunlight at all times.

Heliocentric model

The astronomical model in which the Earth and planets revolve around the Sun.

Geocentric model

The astronomical model in which the Earth is at the center of the universe and all celestial bodies revolve around it.

Astrology

A belief system that suggests a relationship between the positions of celestial bodies and events on Earth.

Astronomy

The scientific study of celestial objects, space, and the universe as a whole.

Greek philosophers' contribution

Developed early forms of the scientific method and made significant contributions to the understanding of astronomy.

Terrestrial planets

Rocky planets that are similar to Earth, including Mercury, Venus, Earth, and Mars.

Jovian planets

Gas giant planets that include Jupiter, Saturn, Uranus, and Neptune.

Dwarf planets

Small celestial bodies that orbit the Sun and are similar to planets but do not clear their orbital path.

Asteroids

Small rocky bodies that orbit the Sun, primarily found in the asteroid belt between Mars and Jupiter.

Comets

Icy celestial bodies that release gas and dust, forming a glowing coma and tail when near the Sun.

Nuclear Fusion

The process that powers the Sun, where hydrogen atoms fuse to form helium, releasing energy.

Galaxy

A massive system of stars, stellar remnants, interstellar gas, dust, and dark matter.

Lunar eclipse

An event where the Earth passes between the Sun and the Moon, casting a shadow on the Moon.

Solar eclipse

An event where the Moon passes between the Sun and the Earth, casting a shadow on Earth.

Eclipse

The obscuring of one celestial body by another.

Umbra

The fully shaded inner region of a shadow during an eclipse.

Penumbra

The partially shaded outer region of a shadow during an eclipse.

Tides

The periodic rise and fall of sea levels caused by the gravitational forces exerted by the Moon and Sun.

Albedo

The measure of reflectivity of a surface, particularly in astronomy.

Prograde motion

The movement of a celestial body in the same direction as the rotation of its planet.

Retrograde motion

The apparent reverse movement of a planet when viewed from another planet's perspective.