The Universe

The universe contains billions of galaxies, each with billions of stars.

Our Sun

The Sun is a medium-sized star at the center of our solar system.

Mass
1.989 × 10³⁰ kg
Radius
696,340 km

What Is a Star?

Stars are massive spheres of hot gas powered by nuclear fusion.

Nebula

Stars are born inside clouds of gas and dust called nebulae.

Protostar

Fusion Process
4H → He + energy
Lifetime
~10 billion years

Gravity pulls the gas together, heating it up.

Main Sequence

Hydrogen fusion begins. The star is stable.

Red Giant

Supernovae can outshine entire galaxies for a brief moment, releasing more energy than the Sun will in its entire lifetime!
Peak Brightness
10¹⁰ L☉
H
Hydrogen
Stars & water
Density
10⁶ g/cm³
Mass Limit
1.44 M☉ (Chandrasekhar)
Density
10¹⁴ g/cm³
Magnetic Field
10¹² Gauss
Event Horizon
Schwarzschild radius
No Hair Theorem
Mass, charge, spin only
He
Helium
Stars & balloons
C
Carbon
Life & diamonds
O
Oxygen
Air & water
Fe
Iron
Blood & Earth core
Au
Gold
Jewelry & electronics

The star expands as it runs out of fuel.

Supernova

The star explodes, spreading elements across space.

We Are Stardust

Supernovae create the heavy elements that make up planets, life, and everything around us.

White Dwarf

For stars like our Sun, the core becomes a dense white dwarf after the outer layers are ejected.

Neutron Star

Massive stars collapse into incredibly dense neutron stars, with intense magnetic fields.

Black Hole

The most massive stars collapse into black holes, where gravity is so strong that not even light can escape.

The Cycle Continues

From stardust to stars, and back again

Every atom in your body was forged in the heart of a star. The universe recycles matter in an endless cosmic dance.