Astronomy

List what you know about astronomy so already.

• Objects seen in the sky that are not connected to Earth or its atmosphere are called celestial objects.

Examples: sun, moon, stars, comets

Celestial Motion

• If you watch the sky, it is clear that it changes over time

• Objects appear to move across the sky from east to west along an arc shape

Models of the Universe

• Geocentric model – Earth in center of universe• Heliocentric model – sun in center of

universe, the model we have today

Stars

• Hot, glowing balls of gas.

Galaxies

• Stars within systems of spiral shapes

Nebulae

• Clouds of gas and dust lit up by stars

Our Solar System

• Earth’s sun is an average sized star• Light travels at a speed of 300,000 km/sec,

meaning that it takes light less than 10 minutes to be seen from Earth

Planets

• Planets are bodies that are at least partly solid, orbit the sun, and give off mainly reflected sunlight.

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• Mars, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune

Terrestrial Planets

• The four innermost planets that are small and dense

• Mercury, Venus, Earth, Mars

Jovian Planets

• The four large planets that are less dense• Jupiter, Saturn, Uranus, Neptune• Gas giants

Asteroids

• Solid bodies having no atmosphere that orbit the sun.

• Most are in-between Mars and Jupiter• Meteors are chunks of matter that enter an

atmosphere and give off light

Comets

• Comets move in elliptical orbits, but they are more elongated paths than planets

• Ball of ice that heats up and turns into a cloud of gases

Motion in the Solar System

• The force that keeps planets in orbit around the sun is gravity. Gravity keeps moons orbiting around the planets.