When I heard the learn'd astronomer,
When the proofs, the figures,
were ranged in columns before me,
When I was shown the charts and diagrams,
to add, divide, and measure them
When I sitting heard the astronomer where he lectured with
much applause in the lecture-room,
How soon unaccountable I became tired and sick,
Till rising and gliding out I wander'd off by myself,
In the mystical moist night-air, and from time to time,
Look'd up in perfect silence at the stars.

• How can we measure the distances to the stars?
• How do we know the Sun and stars are in motion with respect to each other?
• How can we describe a star’s brightness?
• How do atoms in stars produce emission and absorption lines?
• What can we learn by combining information about the temperatures and luminosities of the stars?
• How can we determine the masses of stars?