______________ planets are large planets with deep, massive gas atmospheres, which are mostly made of hydrogen and helium.

__________ is the fifth closest planet to the sun and the largest planet in the solar system.

____________ is the sixth closest planet to the sun.

_________ is the least dense of all the planets.

___________ is the seventh planet from the sun.

_________ has retrograde rotation.

_________ is the planet in the solar system farthest from the sun.

The _____________ is a region in the solar system, beginning at the orbit of Neptune, that is thought to contain matter that was left over from the formation of the solar system.

A __________ is an icy body that releases gas and dust.

The ___________ is a region that surrounds the solar system and extends 30 trillion kilometers from the sun.

Asteroids in our solar system are typically small, irregularly shaped, rocky objects orbiting the sun in a belt between ______________.

When a meteoroid enters Earth’s atmosphere and burns up, it is called a _________.

Every day there are _________ of meteors in Earth’s atmosphere.

When a meteoroid reaches Earth’s surface without burning up, it is called a ____________.

__________ is a force of attraction inherent to all matter in the universe.

The strength of gravity between two objects depends on their individual _________ and their __________ from each other.

T/F: Gravity is a relatively weak force.

The _______________ planets are made primarily of rocky and metallic materials.

Terrestrial planets have little ___________ material and thin atmospheres.

The terrestrial planets are relatively (small/large) planets.

Mercury is composed of volcanic rock and is heavily _____________.

Mercury’s core is made of _________.

Since Mercury lacks a(n) ____________, there is nothing to shield it from the harsh radiation of the sun.

________ is the second planet from the sun.

Venus has a hotter surface temperature than Mercury does, which is a result of the ________________.

Venus rotates in a _________ direction.

The surface of Mars is largely made of dark __________ basalt.

The ________________ in the rock gives Mars its orange-red appearance.

Unlike on Earth, the thin atmosphere of Mars is mainly composed of _______________.

Which is the correct order of planets, starting with closest to the sun?

A day is longer than a year on this planet

Which planet has the shortest year?

_____________, such as the Milky Way galaxy in which Earth is located, are made up of millions to billions of stars.

A __________________ is the smallest large-scale structure in the universe.

A solar system consists of at least one _________ and all the objects that orbit it.

Galaxies are moving __________ _______________ in the Universe.

Newton helped to show that the force of ___________ influenced objects in space.

Einstein’s ____________________ showed that the universe was expanding.

The first scientist to suggest that the universe was expanding was ____________________.

Edwin _____________ used the Doppler effect to determine how galaxies are moving.

George ________ built on the work of his predecessors to develop a theory that explained how light elements formed during the early universe.

The _____________ ________________ is the change in an observed wavelength or frequency of a wave that occurs when either the source of the wave or the observer of the wave is moving.

A __________________ is an explanation for why things work or how things happen.

___________________ are summaries or statements that describe a wide range of observations and results of experiments.

Scientific laws describe what happens and theories explain why things happen.

Scientific theories describe what happens and laws explain why things happen.

Scientific laws describe what happens and theories explain why things happen.

Scientific theories describe what happens and laws explain why things happen.

Scientific theories describe what happens and laws explain why things happen.

T/F: Scientists are done investigating the origin of the universe.

Terrestrial Planet or Gas Giant: rocky

Terrestrial Planet or Gas Giant: gas/ice

Terrestrial Planet or Gas Giant: Jupiter

Terrestrial Planet or Gas Giant: Saturn

Terrestrial Planet or Gas Giant: Uranus

Terrestrial Planet or Gas Giant: Neptune

Terrestrial Planet or Gas Giant: Saturn

Terrestrial Planet or Gas Giant: Mercury

Terrestrial Planet or Gas Giant: Neptune

Terrestrial Planet or Gas Giant: Earth

Terrestrial Planet or Gas Giant: Mars

Terrestrial Planet or Gas Giant: Higher in mass

Terrestrial Planet or Gas Giant: Closer to the sun

Terrestrial Planet or Gas Giant: Farther from the sun

Terrestrial Planet or Gas Giant: Farther from the sun

Terrestrial Planet or Gas Giant: Lower density

Terrestrial Planet or Gas Giant: Larger radius

Terrestrial Planet or Gas Giant: Shorter period

Terrestrial Planet or Gas Giant: Longer period

We live on a ....

The largest planet is a...

The smallest planet is a...

Also known as "rocky"

Also known as "jovian"