Which term best describes the layer of gas surrounding a planet?

Which term best describes the layer of gas surrounding a planet?

• A. Cryosphere
• B. Atmosphere
• C. Hydrosphere
• D. Lithosphere

Answer: (B)

The main idea is the gaseous envelope that surrounds a planet. This layer is called the atmosphere, held in place by gravity and varying in thickness and composition from world to world. It is what we breathe and what drives weather and climate, and on Earth it’s mainly nitrogen and oxygen. It also shields living things from some solar radiation. This contrasts with the cryosphere, which is the frozen part of the planet’s surface and near-surface environment; the hydrosphere, which includes all water — oceans, rivers, lakes, and groundwater; and the lithosphere, which is the solid rocky outer shell.

The main idea is the gaseous envelope that surrounds a planet. This layer is called the atmosphere, held in place by gravity and varying in thickness and composition from world to world. It is what we breathe and what drives weather and climate, and on Earth it’s mainly nitrogen and oxygen. It also shields living things from some solar radiation. This contrasts with the cryosphere, which is the frozen part of the planet’s surface and near-surface environment; the hydrosphere, which includes all water — oceans, rivers, lakes, and groundwater; and the lithosphere, which is the solid rocky outer shell.