Sun: Facts - NASA Science

Overview

• The Sun is a 4.5 billion-year-old yellow dwarf star.
• Composed primarily of hydrogen and helium.
• Located about 93 million miles (150 million km) from Earth.
• It's the solar system's only star, critical for life on Earth.

Key Characteristics

Temperature

• Core: ~27 million degrees Fahrenheit (15 million degrees Celsius).
• Sustains nuclear fusion, preventing collapse.

Size and Scale

• About 100 times wider than Earth.
• Approximately 10 times wider than Jupiter.

Structure

• Center of our solar system, holds planets in orbit.
• Lacks a solid surface; consists of plasma.

Rotation and Movement

• Made up of super-hot plasma, rotates at varying speeds.
  • Equator: 25 Earth days for one rotation.
  • Poles: 36 Earth days for one rotation.

Visible Features

• Photosphere: Visible 'surface' of the Sun.
• Chromosphere & Corona: Outer layers, home to solar prominences, flares, and coronal mass ejections.

Orbit & Solar System Interactions

• No moons, but influences orbits of planets, asteroids, etc.
• Inhabitants of the solar system revolve around it.

Current Research and Exploration

• Various spacecraft study the Sun (e.g., Parker Solar Probe, SOHO).

Historical and Future Evolution

• Formed about 4.6 billion years ago from a gas and dust cloud.
• Future: Will expand into a red giant and then shrink to a white dwarf.

Atmosphere and Surface Phenomena

• Atmosphere includes the photosphere, chromosphere, and corona.
• Key Features:
  • Spicules: Jets of solar material.
  • Sunspots: Cooler areas caused by magnetic field.
  • Coronal Holes: Low-density regions in the atmosphere.
  • Solar Flares: Explosions of magnetic energy.
  • Coronal Mass Ejections (CMEs): Clouds of particles affecting Earth.
  • Solar Prominences: Eruptive structures of solar material.

Solar Cycle and Magnetosphere

• Solar activity follows an 11-year cycle.
• Magnetic poles swap approximately every 11 years.
• Solar maximum is a period of high activity.

Impacts on Earth

• Can affect satellites, GPS, and power grids.
• The strongest recorded event: Carrington Event (1859).
• Recent events: 1989 flare, disrupting electricity in Canada.

Quick Facts

• Day Length: 25 Earth days at equator, 36 at poles.
• Orbit: Completes orbit around Milky Way every 230 million years.
• Star Type: G2 V, yellow dwarf.
• Surface Temperature: 10,000 F (5,500 C).
• Corona Temperature: Up to 3.5 million F (2 million C).

Additional Resources

• Explore further with NASA's Heliophysics and Heliopedia.
• Stay updated with NOAA's Space Weather Prediction Center.

By understanding the Sun, scientists gain insights into other stars and the formation and evolution of the solar system.