Astronomy 4 (for my love)

According to modern science, approximately how old is the Sun?

• 4 1/2 billion years

• 25 million years

• 10,000 years

• 400 million years

The Sun will exhaust its nuclear fuel in about

• 5000 AD

• 5 million years

• 5 billion years

• 50 billion years

Which of the following correctly describes how the process of gravitational contraction can make a star hot?

• Gravitational contraction involves nuclear fusion, which generates a lot of heat.

• When a star contracts in size, gravitational potential energy is converted to thermal energy.

• Heat is generated when gravity contracts, because gravity is an inverse square law force.

• Gravitational contraction involves the generation of heat by chemical reactions, much like the burning of coal

What two physical processes balance each other to create the condition known as gravitational equilibrium in stars?

• the strong force and the weak force

• the inward pull of gravity and outward pressure

• the inward pull of gravity and surface tension

• the strong force and the electromagnetic force

The source of energy that keeps the Sun shining today is

• nuclear fission

• gravitational contraction

• chemical reactions

• nuclear fusion

When we say that the Sun is a ball of plasma, we mean that

• the Sun is made of material that acts like a liquid acts on Earth.

• the Sun is made of atoms and molecules.

• the Sun consists of gas in which many or most of the atoms are ionized (missing electrons).

• the Sun is roughly the same color as blood

What is the Sun made of (by mass)?

• 70% hydrogen, 28% helium, 2% other elements

• 100% hydrogen and helium

• 50% hydrogen, 25% helium, 25% other elements

• 90% dark matter, 10% ordinary matter

From center outward, which of the following lists the "layers" of the Sun in the correct order?

• core, radiation zone, convection zone, corona, chromosphere, photosphere

• core, convection zone, radiation zone, corona, chromosphere, photosphere

• core, radiation zone, convection zone, photosphere, chromosphere, corona

• core, corona, radiation zone, convection zone, photosphere, chromosphere

What are the appropriate units for the Sun's luminosity?

• watts

• joules

• Newtons

• kilograms

The Sun's surface, as we see it with our eyes, is called the

• chromosphere

• photosphere

• corona

• core.