1. 2. 3. 4. 5. How fast does light travel? How can this speed be measured? How is the light from an ordinary light bulb different from the light

1. 2. 3. 4. 5. How fast does light travel? How can this speed be measured? How is the light from an ordinary light bulb different from the light emitted by a neon sign? How can astronomers measure the temperatures of the Sun and stars? How can astronomers tell what distant celestial objects are made of? How can we tell if a celestial object is approaching us or receding from us?