The Solar System

The heliocentric system gained support when Galileo observed that

• One side of the moon always faces the Earth

• Most of the smaller planets are closer to the sun

• Venus goes through phases similar to those of Earth's moon

• the orbit of each planet is an ellipse

In a heliocentric system, Earth revolves around

• Mars

• the stars

• the moon

• the sun

The fact that each planet's orbit is an ellipse was discovered by

• Copernicus

• Galileo

• Kepler

• Brahe

The solar system formed from

• an expanding galaxy

• a giant cloud of gas and dust

• an enormous explosion

• a black hole

Small asteroid-like bodies that became the building blocks for the planets are called

• planetesimals

• comets

• meteoroids

• open clusters

The sun produces energy by

• attracting it with the force of gravity

• nuclear fission

• burning fuels such as oil

• nuclear fusion

What layer are you looking at when you look at an image of the sun?

• photosphere

• chromosphere

• corona

• prominence

The solar wind is a stream of electrically charge particles that extend outward from the sun's

• chromosphere

• photosphere

• corona

• core

What do the four outer planets have in common?

• They are much larger than Earth and are made mostly of hydrogen and helium

• They are about the same size as Earth and are made mainly of hydrogen and helium

• They are much larger than Earth and are made mainly of iron

• They are about the same size as Earth and are made mainly of iron

What do all of the inner planets have in common?

• They all have rings

• They all have abundant liquid water

• They all have many moons

• They are all small and have rocky surfaces