Astronomy Practice Exam

What is the Sun primarily classified as?

1. Planet

2. Satellite

3. Star

4. Meteor

The correct answer is: Star

The Sun is primarily classified as a star because it is a massive celestial body that generates energy through nuclear fusion in its core. This process involves the fusion of hydrogen atoms into helium, which releases a tremendous amount of energy in the form of light and heat. This energy output is what makes the Sun a shining example of a main-sequence star, specifically a G-type star in the Hertzsprung-Russell diagram. Stars are typically defined as radiant objects in the universe that have enough mass to sustain nuclear fusion, and the Sun fits this definition perfectly. In contrast, other classifications such as planets, satellites (or moons), and meteors do not generate their own light and heat. Planets orbit stars and do not undergo fusion. Satellites revolve around planets and are not self-luminous. Meteors are simply small rocky or metallic bodies that enter Earth's atmosphere and burn up due to friction; they are not classified as celestial bodies that sustain energy production like stars do. Thus, the classification of the Sun as a star is consistent with its physical properties and its role within the solar system.