Review BBT, Stellar Evo, HR Diagram

What process powers the Sun's energy production?

• Chemical reactions

• Combustion

• Gravitational compression

• Nuclear fusion

Answer explanation

The Sun's energy is produced through nuclear fusion, where hydrogen nuclei combine to form helium, releasing vast amounts of energy. This process is fundamental to the Sun's ability to shine and sustain life on Earth.

Where in the Sun does nuclear fusion occur?

• The surface

• The corona

• The sunspots

• The core

Answer explanation

Nuclear fusion occurs in the core of the Sun, where temperatures and pressures are extremely high, allowing hydrogen atoms to fuse into helium, releasing energy. The other options do not have the necessary conditions for fusion.

What is the primary element involved in fusion within the Sun?

• Oxygen

• Carbon

• Hydrogen

• Helium

Answer explanation

The primary element involved in fusion within the Sun is hydrogen. In the Sun's core, hydrogen nuclei fuse to form helium, releasing vast amounts of energy in the process, which powers the Sun.

What is the result of hydrogen fusion in the Sun?

• Heat disappears

• New hydrogen forms

• Helium and energy are produced

• The Sun cools down

Answer explanation

Hydrogen fusion in the Sun primarily produces helium and releases a significant amount of energy in the form of heat and light, which is essential for sustaining the Sun's brightness and warmth.

EC How does energy from the Sun reach Earth?

• Through convection

• By conduction

• Through particles of matter

• By radiation

Answer explanation

Energy from the Sun reaches Earth primarily by radiation, which is the transfer of energy through electromagnetic waves. Unlike conduction and convection, radiation does not require a medium, allowing it to travel through the vacuum of space.

Why does the Sun shine?

• It burns like firewood

• It releases energy from nuclear fusion

• It reflects light from other stars

• It is made of lava

Answer explanation

The Sun shines because it releases energy from nuclear fusion, a process where hydrogen atoms combine to form helium, releasing vast amounts of energy in the form of light and heat.

What type of energy from the Sun reaches Earth?

• Sound energy

• Mechanical energy

• Electromagnetic radiation (light)

• Electrical energy

Answer explanation

The Sun emits energy primarily as electromagnetic radiation, which includes visible light. This is the type of energy that reaches Earth, enabling photosynthesis and warming the planet.

What happens to a star when it runs out of hydrogen fuel?

• It disappears instantly

• It becomes a planet

• It changes stages in its life cycle

• It explodes immediately

Answer explanation

When a star runs out of hydrogen fuel, it does not disappear or explode instantly. Instead, it changes stages in its life cycle, often expanding into a red giant and eventually evolving into different types of celestial objects.

The Sun is currently in which stage of its life cycle?

• White dwarf

• Main sequence

• Red giant

• Supernova

Answer explanation

The Sun is currently in the main sequence stage of its life cycle, where it fuses hydrogen into helium in its core. This stage lasts for about 10 billion years, and the Sun is approximately halfway through this phase.

Why does the Sun not collapse under its own gravity?

• It spins quickly

• Magnetic fields hold it up

• Fusion creates outward pressure

• Light pushes it outward

Answer explanation

The Sun does not collapse under its own gravity because fusion in its core creates outward pressure. This pressure counteracts the gravitational force, maintaining the Sun's stability.