Astronomical Units & Measurements Glossary

I. What is Synchrotron Emission? Synchrotron emission is a form of electromagnetic radiation that is produced by charged particles moving at relativistic speeds in magnetic fields. This emission is commonly observed in astrophysical environments, such as galaxies, supernova remnants, and clusters of galaxies. The radiation emitted in the form of synchrotron emission is non-thermal, meaning … Read more

I. What is the Tully-Fisher Relation? The Tully-Fisher Relation is a fundamental relationship in astronomy that links the luminosity or brightness of a spiral galaxy to its rotational velocity. It was first discovered in 1977 by astronomers R. Brent Tully and J. Richard Fisher, who found that there is a strong correlation between the luminosity … Read more

I. What is Jeans Mass? In astronomy, Jeans Mass refers to the minimum mass required for a cloud of gas to collapse under its own gravitational pull and form a star or a stellar system. This concept was first introduced by British physicist Sir James Jeans in the early 20th century as a way to … Read more

I. What is an Air Mass in Astronomy? In astronomy, an air mass refers to a large body of air with relatively uniform temperature, humidity, and pressure characteristics. Air masses play a crucial role in shaping weather patterns and climate conditions on Earth. They are responsible for bringing different types of weather systems, such as … Read more

I. What is Cosmological Distance? Cosmological distance refers to the vast distances between celestial objects in the universe. It is the measurement of how far apart objects are in space, and plays a crucial role in our understanding of the universe and its evolution. The vastness of the cosmos means that distances between objects can … Read more

I. What is an Epoch in Astronomy? In astronomy, an epoch refers to a specific point in time that is used as a reference for measuring various celestial phenomena. It serves as a fixed point from which astronomers can track the positions and movements of celestial objects such as stars, planets, and galaxies. The concept … Read more

I. What is the Vega System? The Vega System is a binary star system located in the constellation of Lyra, approximately 25 light-years away from Earth. It is one of the brightest stars in the night sky and has been studied extensively by astronomers due to its proximity and visibility. The system consists of two … Read more

I. What is Deflection Angle? Deflection angle, also known as angular deflection, is a term used in astronomy to describe the change in direction of light rays as they pass through a gravitational field. This phenomenon occurs due to the bending of light caused by the gravitational pull of massive objects such as stars, planets, … Read more

I. What is Transit Photometry Method? Transit photometry is a method used in astronomy to detect exoplanets by measuring the decrease in brightness of a star as a planet passes in front of it. This technique relies on the fact that when a planet transits or crosses in front of its host star, it blocks … Read more

I. What is Parallax? Parallax is a phenomenon in which an object appears to shift its position when viewed from different perspectives. This effect is commonly observed in everyday life, such as when looking out of a moving vehicle and seeing nearby objects appear to move faster than distant ones. In astronomy, parallax is a … Read more