Star System Definition: Galaxy Explained

The question asks to identify the term for a massive cosmic structure containing billions of stars, along with clouds of dust and gases.

Analyzing Celestial System Options

Let's examine each option:

• Universe: This refers to all of space and time and their contents, including planets, stars, galaxies, and all other forms of matter and energy. It is much larger than the described system.
• World: This term typically refers to a planet or a specific region, not a vast collection of stars and gas.
• Galaxy: A galaxy is precisely defined as a gravitationally bound system comprising billions of stars, stellar remnants, interstellar gas, dust, and dark matter. This perfectly matches the question's description.
• Constellation: A constellation is a pattern or group of stars visible in the night sky, often named after mythological figures or animals. It's an apparent pattern, not a massive physical system of stars, dust, and gas.

Based on the definitions, a huge system of billions of stars, dust, and gases is known as a Galaxy.