Background Information
A similar effect happens when a star or galaxy is moving in relation to Earth. When a star comes closer to Earth, the light waves it sends out are squeezed together, which makes its light shift toward the blue side of the spectrum. This is called blueshift. When a star moves away from Earth, its light shifts toward the red side of the spectrum. This is known as redshift.
In 1912, an astronomer named Henrietta Swan Leavitt studied a type of stars called Cepheids. These stars change from bright to dim and then back to bright again. Her findings led to a way of measuring distances to other galaxies and helped support the Big Bang theory about how the universe began.
Stars give off light in many different wavelengths. Just like white light becomes a rainbow when it goes through a prism, starlight can be split into its colors when it goes through a tool called a spectrograph. This creates a pattern of colors with dark lines known as an absorption spectrum. The dark lines show the wavelengths of light that are absorbed in the star’s atmosphere. Each star has a unique spectrum based on the temperature and materials in its atmosphere.
This is the spectrum of star A-091. Each star has its own special spectrum, just like everyone has a unique fingerprint. Look closely at the dark lines.
