Redshift-Space Distortion – Definition & Detailed Explanation – Astronomical Units & Measurements Glossary

I. What is Redshift-Space Distortion? Redshift-space distortion is a phenomenon in astronomy that occurs when the observed redshift of galaxies is affected by their peculiar velocities. In simple terms, redshift-space distortion refers to the apparent stretching or compression of galaxy clusters along the line of sight due to their motion through space. This distortion can … Read more

Lomb-Scargle Periodogram (time series analysis) – Definition & Detailed Explanation – Astronomical Units & Measurements Glossary

I. What is the Lomb-Scargle Periodogram? The Lomb-Scargle Periodogram is a method used in time series analysis to detect periodic signals in unevenly sampled data. It was developed by Lomb in 1976 and later refined by Scargle in 1982. This technique is particularly useful in fields such as astronomy, where observations may be taken at … Read more

Poynting-Robertson Effect – Definition & Detailed Explanation – Astronomical Units & Measurements Glossary

I. What is the Poynting-Robertson Effect? The Poynting-Robertson Effect, named after John Henry Poynting and Howard P. Robertson, is a phenomenon in astrodynamics that describes the effect of radiation pressure on small particles in space. When a small particle, such as a dust grain or asteroid, is exposed to sunlight, it absorbs and re-emits photons, … Read more

Friedmann Equations – Definition & Detailed Explanation – Astronomical Units & Measurements Glossary

I. What are the Friedmann Equations? The Friedmann Equations are a set of equations in cosmology that describe the expansion of the universe. They were first derived by the Russian physicist Alexander Friedmann in the 1920s, and later refined by Belgian physicist Georges Lemaître. These equations are a key component of the Friedmann-Lemaître-Robertson-Walker (FLRW) metric, … Read more