Define protostar.

What is meant by saying a main-sequence star is in equilibrium?

After the main sequence, a low-mass star becomes a ______, then ejects its outer layers as a ______, before its core collapses into a ______.

Why does a low-mass star's core shrink and heat up as it becomes a red giant?

What happens to a white dwarf over time?

Describe the stages of a high-mass star's life cycle after the main sequence.

Define supernova.

True or False? A neutron star can form from the collapse of a low-mass star.

Define the Milky Way.

Define the Sun.

Why do the planets orbit the Sun, rather than the Sun orbiting them?

How does a star's colour relate to its surface temperature?

The Sun radiates most of its energy in the ______, ______ and ______ regions of the electromagnetic spectrum.

Which two isotopes of hydrogen fuse together in a star's core to form helium?

Why does nuclear fusion prevent a stable star from collapsing under gravity?

True or False? The Sun is one of the largest stars in the Milky Way.

Define light-year.

The diameter of the Milky Way is approximately ______ light-years.

Define redshift.

How does the Doppler effect change the wavelength and frequency of waves in front of and behind a moving source?

What is the relationship between a galaxy's distance from Earth and the redshift observed in its light?

What evidence from distant galaxies supports the Big Bang theory?

According to the Big Bang theory, how did the Universe begin?

True or False? The balloon analogy shows that galaxies move apart because space itself expands between them.