* The Doppler Effect: The red shift is a result of the Doppler effect, which we experience in everyday life with sound. Imagine a car driving towards you with its horn honking. The sound seems higher pitched (shorter wavelength) as it approaches. As the car moves away, the sound gets lower pitched (longer wavelength).
* Light as Waves: Light also behaves as waves, and the Doppler effect applies to it as well. When an object moves away from us, the wavelengths of its light are stretched out, shifting them towards the red end of the visible light spectrum.
* Measuring Red Shift: Astronomers can measure the amount of red shift by comparing the wavelengths of light emitted from a distant object with known wavelengths of elements on Earth. The larger the red shift, the faster the object is moving away.
Key Takeaways:
* Red shift indicates recession: A red shift tells us that a celestial object is moving away from us.
* The degree of red shift reveals speed: The amount of red shift directly corresponds to the object's speed. The greater the red shift, the faster the object is moving away.
Important Note: Red shift is not just about movement. It's also a key piece of evidence for the expanding universe. The fact that most distant galaxies show red shifts indicates that the universe is expanding and that everything is moving further apart.
