Astronomy Study Guide

Flashcards covering astronomy concepts, including geocentric and heliocentric theories, objects in the solar system, Earth's movements, seasons, and lunar phases.

Geocentric Theory

States that Earth is at the center of the Solar System & all objects revolve around Earth.

Heliocentric Theory

States that the Sun is at the center of the Solar System & all objects revolve around the Sun.

Asteroid

Objects revolving around the Sun that are too small & numerous to be a planet.

Comet

Ball of ice & dust whose orbit is a long, narrow ellipse (oval).

Meteor

A streak of light in the sky produced by a burning meteoroid in the atmosphere.

Meteorite

A meteoroid that hits Earth's surface.

Meteoroid

A chunk of rock & dust in space.

Rotation (definition)

Earth spinning on its axis.

How long does it take for Earth to make one rotation?

24 hours

What does the rotation of Earth cause us to experience?

Day & night.

Revolution (definition)

The Earth moving along its orbit around the Sun.

How long does it take for Earth to make one revolution around the sun?

365 days.

How long does it take the moon to make one revolution around Earth?

27-29 days

Axis (definition)

An imaginary line which passes through Earth.

What angle is the tilt of Earth's axis?

23 degrees

What does the tilt of Earth's axis cause us to experience?

Our 4 Seasons

Why is it that we experience a leap year every 4 years?

It takes 365 1/4 days for Earth to fully revolve & after 4 years the 1/4 days add up to a full extra day.

Gravity

The attractive force between 2 objects.

Inertia

Tendency of a moving object to keep moving or a still object to remain still until a force acts upon it.

How do gravity and inertia work together to keep Earth and other objects in motion around the sun?

Gravity keeps Earth on its orbital path while inertia keeps the Earth continuously moving around the sun.

Why does Earth experience 4 seasons?

The combination of Earth's rotation on a tilted axis while it revolves around the Sun.

Summer Solstice

Longer days (sunlight) as sun's rays hit more directly on the Northern Hemisphere.

When does the Summer Solstice occur?

Approximately June 21st.

Winter Solstice

Shorter days (sunlight) as Sun's rays hit the Northern Hemisphere indirectly.

When does the Winter Solstice occur?

Approximately December 21st.

Spring (Vernal) Equinox

Equal amount of day & night (light & darkness).

When does the Spring (Vernal) Equinox occur?

Around March 21st.

Fall (Autumnal) Equinox

Equal amount of day & night (light & darkness).

When does the Fall (Autumnal) Equinox occur?

Around September 21st.

Why is it that we see the moon differently throughout a given month?

The position of the moon changes as it revolves around Earth, changing the amount of sunlight reflecting off its surface.

Moon Phase 2

Waxing Crescent

Moon Phase 3

1st Quarter

Moon Phase 4

Waxing Gibbous

Moon Phase 5

Full Moon

Moon Phase 6

Waning Gibbous

Moon Phase 7

3rd Quarter

Moon Phase 8

Waning Crescent

Moon Phase 1

New Moon