Age of the Universe
The fastest thing in the universe.
Visible light
The most widely accepted theory of the universe’s origin.
Big Bang Theory
Stars form from vast clouds of dust and gas called this.
Nebula
Galaxies consist of stars, gases, and this.
Space dust
A planet must orbit this.
A star
The distance light travels in one year.
Light year
According to the Big Bang, the universe began as this.
Dense hot single point
This force causes the nebula to condense and collapse.
Gravity
Groups of 10 to 10,000 galaxies are called this.
Clusters
A planet must have enough mass and gravity to form this shape.
Round
The estimated age of the universe.
13.7 Billion
After the Big Bang, the universe did this rapidly.
Expanded
As the nebula collapses, it begins to do these two things.
Spin and Heat Up
More than one group of clusters separated by voids is called this.
Superclusters
A planet must clear its orbit of these.
Asteroids
: Light is useful for measuring what?
Distances
After expansion, the universe cooled and this formed.
Matter
Gravity pulls in more particles until this begins.
Nuclear Reactions
The Milky Way belongs to this group of 32 galaxies.
Local group
What are Mercury, Venus, Earth, and Mars are called the
Inner planets (rocky planets)
Scientists use this method to estimate the universe’s age.
Backward
The universe is constantly doing this today.
Once nuclear reactions begin, the nebula becomes this.
Star
Each galaxy contains hundreds of billions of these.
Stars, gases, Dust
What are Jupiter, Saturn, Uranus, and Neptune are called the
Outer Planets (gas giants)