Sun

Definition

The Sun is the star at the center of the Solar System, around which the Earth and other planets orbit. It is the dominant gravitational force in the Solar System, accounting for 99.8% of the system's mass. The Sun is a nearly perfect sphere of hot plasma, with an internal temperature of 15 million degrees Celsius.

5 Must Know Facts For Your Next Test

1. The Sun is the closest star to Earth, located approximately 93 million miles (150 million kilometers) away.
2. The Sun's core is the hottest part of the Sun, reaching temperatures of around 15 million degrees Celsius.
3. Nuclear fusion reactions in the Sun's core are the primary source of the Sun's energy, converting hydrogen into helium.
4. The Sun's gravitational pull is responsible for keeping the planets in orbit around it, forming the Solar System.
5. The Sun's magnetic field extends far beyond the planets, creating the heliosphere, a bubble-like region of the Sun's influence that extends well past the orbit of Pluto.

Review Questions

• Explain the role of the Sun in the formation and stability of the Solar System.
  • The Sun is the dominant gravitational force in the Solar System, accounting for 99.8% of the system's mass. Its powerful gravitational pull is responsible for keeping the planets, dwarf planets, and other objects in orbit around it, forming the stable Solar System we observe today. The Sun's gravity is what holds the planets in their elliptical orbits, and its influence extends far beyond the planets, creating the heliosphere that defines the boundaries of the Solar System.
• Describe the process of nuclear fusion that occurs in the Sun's core and how it generates the Sun's energy.
  • The Sun's core is an extremely hot and dense region, reaching temperatures of around 15 million degrees Celsius. Within this core, nuclear fusion reactions take place, where the nuclei of hydrogen atoms are combined to form helium nuclei. This process of nuclear fusion releases a tremendous amount of energy, which is the primary source of the Sun's radiant energy. As the Sun's core fuses hydrogen into helium, it generates the vast majority of the Sun's energy output, powering the Sun's luminosity and enabling it to sustain the Solar System.
• Analyze the significance of the Sun's magnetic field and its influence on the heliosphere and the overall Solar System.
  • The Sun's magnetic field extends far beyond the orbits of the planets, creating the heliosphere, a bubble-like region of the Sun's influence that extends well past the orbit of Pluto. This magnetic field plays a crucial role in shaping the Solar System and protecting the planets from harmful cosmic radiation. The heliosphere acts as a shield, deflecting charged particles and high-energy radiation from outside the Solar System, creating a relatively safe and stable environment for the planets and their inhabitants. Additionally, the Sun's magnetic field is responsible for various space weather phenomena, such as solar flares and coronal mass ejections, which can have significant impacts on Earth's atmosphere and technological systems.

Related terms

Solar System: The gravitationally bound system of the Sun and the objects that orbit it, including planets, dwarf planets, moons, asteroids, comets, and other small bodies.

Fusion: The process by which the nuclei of light elements, such as hydrogen, are combined to form heavier nuclei, releasing a large amount of energy in the process.

Gravity: The fundamental force of attraction that exists between any two masses, acting to pull them towards each other.