What is Astrophysics,Why Astrophysics, Define Astrophysics Astrophysics Meaning, Physics concepts,Explanation . Astrophysics is a branch of space science that applies the laws of physics and chemistry to explain the birth, life and death of stars, planets, galaxies, nebulae and other objects in the universe. It has two sibling sciences, astronomy and cosmology, and the lines between them blur. Among the objects studied are the Sun, other stars, galaxies, extrasolar planets, the interstellar medium and the cosmic microwave background. Their emissions are examined across all parts of the electromagnetic spectrum, and the properties examined include luminosity, density, temperature, and chemical composition. Astrophysicists typically apply many disciplines of physics, including mechanics, electromagnetism, statistical mechanics, thermodynamics, quantum mechanics, relativity, nuclear and particle physics, and atomic and molecular physics. The majority of astrophysical observations are made using the electromagnetic spectrum. Radio astronomy,Infrared astronomy ,Optical astronomy Ultraviolet, X-ray and gamma ray astronomy