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Sun

The Sun is the star at the center of the Solar System and the dominant source of light and heat for Earth.

By Ethan Anderson| Reviewed by Olivia Bennett, Standards & Fact-Checking Lead| Updated July 26, 2026|2 min read| Fact-checked

The Sun is the star at the center of the Solar System and the dominant source of light and heat for Earth. It contains more than 99% of the Solar System’s mass and powers life on Earth through the energy produced by nuclear fusion in its core. The Sun is classified as a G-type main-sequence star and is about 4.6 billion years old.

Characteristics

The Sun is a sphere of hot plasma made mostly of hydrogen and helium. It is classified as a G-type main-sequence star and is considered an average-sized star by astronomical standards.

Structure and energy production

The Sun’s interior includes the core, radiative zone, and convective zone, while its outer layers include the photosphere, chromosphere, and corona. Its core produces energy through nuclear fusion, which is released as light, heat, and other radiation.

Role in the Solar System

The Sun dominates the Solar System gravitationally and supplies the energy that drives Earth’s weather, climate, ocean currents, and photosynthesis. Without it, Earth would not support life as we know it.

Observation and significance

The Sun has been studied since antiquity and remains a central object in astronomy. It also holds cultural importance across many societies as a symbol, deity, or source of life.

Key facts

  • The Sun is the central star around which Earth and the other planets orbit.
  • It provides the light and heat that make life on Earth possible.
  • Its energy is generated by nuclear fusion in the core, converting hydrogen into helium.
  • The Sun accounts for more than 99% of the Solar System’s total mass.
  • It is commonly described as a yellow dwarf or G-type main-sequence star.
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Canadian context

The Sun is directly relevant to Canadian climate, seasons, daylight variation, solar energy, and space science education across Canada.

Frequently asked questions

What is the Sun?
The Sun is the star at the center of the Solar System and the source of most of the energy that reaches Earth.
How old is the Sun?
The Sun is about 4.6 billion years old.
What is the Sun made of?
It is made mostly of hydrogen and helium in a hot plasma state.
How does the Sun produce energy?
The Sun produces energy through nuclear fusion in its core, mainly converting hydrogen into helium.
Why is the Sun important for Earth?
It provides the light and heat needed for life and drives weather, climate, seasons, and photosynthesis.

References

  1. Britannica
    Supports: Defines the Sun as the star around which Earth and the other solar system bodies revolve, and notes its dominant mass and role as a source of energy.
  2. Britannica
    Supports: Provides age, mass, diameter, temperature, spectral type, and rotation details for the Sun.
  3. National Geographic Society
    Supports: Describes the Sun’s influence on weather, ocean currents, seasons, climate, and photosynthesis, and lists its major layers.
  4. Natural History Museum
    Supports: Gives key facts including the Sun’s radius, temperature, mass share of the Solar System, star type, and composition.