1. Describe the difference between red and blue wavelengths of light and why it is important to understanding the movement of galaxies.

The difference between red and blue wavelengths of light lies in their respective positions on the visible light spectrum. Red light has a longer wavelength and lower frequency, while blue light has a shorter wavelength and higher frequency.<br /><br />In the context of understanding the movement of galaxies, the red and blue wavelengths of light is crucial in determining the velocity of galaxies relative to Earth. This is achieved through a technique called redshift and blueshift.<br /><br />When a galaxy is moving away from Earth, the light it emits is stretched, resulting in a shift towards the red end of the spectrum. This phenomenon is known as redshift. Conversely, when a galaxy is moving towards Earth, the light it emits is compressed, resulting in a shift towards the blue end of the spectrum, known as blueshift.<br /><br />By measuring the degree of redshift or blueshift in the light from a galaxy, astronomers can determine the galaxy's velocity and, consequently, its distance from Earth. This information is essential for mapping the large-scale structure of the universe and understanding the expansion of the cosmos.<br /><br />In summary, the difference between red and blue wavelengths of light is important for understanding the movement of galaxies because it allows us to measure their velocities and distances, providing insights into the structure and evolution of the universe.