03 The Solar System Free Online FlashCards

What was the solar nebula?

The solar nebula was the rotating disk of gas and dust formed as a collapsing interstellar cloud flattened; the Sun formed at its center.

Why did rocky planets form close to the Sun?

Near the Sun, high temperatures allowed heat-resistant rock and metal to condense into solids, supplying material for the four inner rocky planets.

How does the Sun dominate the Solar System?

The Sun contains about 99.8% of the Solar System’s mass, and its gravity holds the system together.

What three criteria define a planet in the Solar System?

A Solar System planet orbits the Sun, is nearly round because of its own gravity, and has cleared most other objects from its orbital neighborhood.

Name the eight planets in order from the Sun.

Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.

What is a moon?

A moon, or natural satellite, is a body that orbits a planet or another larger object.

What distinguishes a dwarf planet from a planet?

A dwarf planet orbits the Sun and is nearly round, but has not cleared its orbital neighborhood and is not a moon.

How do meteoroid, meteor, and meteorite differ?

A meteoroid is a small rock or metal piece in space; a meteor is the streak of light it produces in an atmosphere; a meteorite is a piece that reaches the ground.

How did accretion build planets?

Accretion is the gradual growth of bodies as they gather material. Colliding dust and ice grains built clumps, planetesimals, and eventually planets and moons.

What helped prevent the asteroid belt from becoming a planet?

The asteroid belt did not become a planet in part because of Jupiter’s gravitational influence.

What powers the Sun’s energy production?

In the Sun’s core, nuclear fusion converts hydrogen into helium and releases energy that eventually reaches Earth as sunlight and heat.

How do gas giants differ from ice giants?

Jupiter and Saturn are gas giants composed mostly of hydrogen and helium; Uranus and Neptune are ice giants with larger proportions of substances such as water, ammonia, and methane beneath their atmospheres.