What is Doppler blueshift?
Q: What is Doppler blueshift?
A: Doppler blueshift is a decrease in wavelength caused by relative motion, even outside the visible spectrum. It occurs when a source of light moves towards an observer.
Q: How can astronomers use Doppler blueshift to determine relative motion?
A: Astronomers can use Doppler blueshift to determine relative motion by observing changes in the wavelength of light from distant objects. For example, if they observe spiral galaxies, the side spinning toward us will have a slight blueshift compared to the side spinning away from us. They can also measure relativistic jets that appear blueshifted and nearby stars such as Barnard's Star that are moving towards us resulting in a very small blueshift.
Q: How do astronomers know how far the light gets shifted?
A: Astronomers know how far the light gets shifted because certain chemical elements like calcium or oxygen have unique fingerprints of light that no other element has. By looking at the difference between where these spectral lines are and where they should be, astronomers can tell how far away an object is, whether it is moving towards or away from them, and also how fast it is going since faster movement results in greater distance between spectral lines and their expected position.
Q: What causes redshift?
A: Redshift is caused by movement of a source away from an observer which increases its wavelength. It occurs when an object moves further away from Earth due to expansion of space-time or cosmic expansion caused by dark energy pushing matter apart over time.
Q: What does "high z" mean?
A: High z refers to objects with high redshifts which indicates that they are very distant and moving rapidly away from Earth due to cosmic expansion caused by dark energy pushing matter apart over time.
Q: How does cosmological redshift differ from Doppler blueshift?
A: Cosmological redshift differs from Doppler Blueshift because cosmological redshift occurs due to cosmic expansion while Doppler Blueshift occurs due to relative motion between two objects such as one object approaching another object or one component of a binary star system moving towards Earth.
