ch 4 Light and Telescopes Lecture Review

Light and Telescopes: Understanding Our Universe

The Fundamental Role of Light in Astronomy

• Almost all knowledge acquired about the Universe beyond Earth originates from light.
• To understand the Universe, it is crucial to comprehend:
  • The fundamental properties of light.
  • How telescopes are utilized to collect and analyze light.

Properties of Light

Speed of Light

• Light travels at an immense speed of 300,000 \text{ km/s} (or 3 \times 10^5 \text{ km/s}) in the vacuum of space.
• The speed of light was first accurately measured by Ole Rømer while observing the moons of Jupiter, specifically the eclipses of Io, noting variations in timing depending on Earth's position relative to Jupiter.
• The speed of light (c) is constant in a vacuum, regardless of its frequency or wavelength.

Light as an Electromagnetic Wave

• Light is fundamentally an electromagnetic wave.
• Unlike other waves such as sound waves (which require a material medium like air or water) or water waves, light does not necessitate a material medium (or