The Beginning
This event marks the start of the universe.
The big bang
The force that keeps planets orbiting stars.
Gravity
The Sun is this type of object.
Star
This scientist developed the theory of relativity.
Albert Einstein
The universe contains billions of these giant star systems.
Galaxies
Scientists believe the universe began about this many years ago.
13.8 billion years ago.
Our galaxy is called this.
Milky Way
A group of stars, gas, and dust held together by gravity.
This astronomer discovered that galaxies are moving away from us.
Edwin Hubble
Scientists use these powerful tools to study distant space.
Telescopes
After the Big Bang, the universe started doing this.
Expanding
This is the name for a giant explosion of a dying star.
Supernova
The closest star to Earth.
The sun
This scientist proposed the Big Bang Theory in the 1920s.
Georges Lemaître
Most scientists believe the universe is doing this over time.
Expanding
This tiny, hot, dense state existed before the universe expanded.
Singularity
These objects have gravity so strong that even light cannot escape.
Black Holes
This happens when a star runs out of fuel.
Dies or collapses
This physicist studied black holes and wrote A Brief History of Time.
This mysterious substance makes up most of the universe’s matter.
Dark matter
This evidence shows the universe is still expanding today.
Redshift
The leftover heat from the Big Bang is called this.
Cosmic microwave background. CMB
These massive clouds in space are where stars are born.
Nebulae
This scientist discovered the laws of motion and gravity.
Isaac Newton
This mysterious energy may be causing the universe’s expansion to speed up.
Dark energy