Early Universe
The theory that states the universe began about 13.8 billion years ago.
The Big Bang Theory
The most accepted explanation for how the solar system formed.
The Nebular Theory
Where the Sun forms in the solar nebula.
The center
The gradual buildup of material by collisions.
Accretion
Inner solar system planets are mostly made of this.
Rock and Metals (Heavier materials)
The first two elements formed in the early universe.
Hydrogen and Helium
The inward contraction of matter due to gravity.
Gravitational Collapse
The process that powers the Sun.
Nuclear Fusion
Small bodies that are building blocks of planets.
Planetesimals
Outer solar system planets contain large amounts of this.
Gases and ices
Large clouds of gas and dust in space where stars can form.
Nebulae
What happens to temperature as particles collide more often during collapse.
They increase
A “baby” star in its earliest stage.
A Protostar
Moon-to-Mars sized bodies that may become planets.
Protoplanets
The distance where gases can freeze into solid ice.
The frost line
A nebula that specifically forms new stars is often called this.
Stellar Nursery
The shape the collapsing cloud flattens into.
A disk
The current stage of our Sun.
A Yellow Dwarf
Region where many planetesimals are found beyond Neptune.
Kuiper Belt
The region where liquid water can exist.
The Goldilocks Zone
The name of the nebula that formed our solar system.
The Solar Nebula
The cause of why the gases and material flattens into a disk.
Rotation
The force that allows hydrogen nuclei to combine in the Sun’s core.
Extreme Temperature and Pressure
Moons that are said to orbit back, are said to orbit in _____________? An example is Triton with Neptune.
Retrograde
Two planets located in the Goldilocks Zone.