Accretion. Astrophysics. Astrophysics People have gazed at the stars, given them names, and observed their changes for thousands of years.
NASA joined the ancient pursuit of knowledge of our universe comparatively recently. Astrophysics. Astrophysics (from Greek astron, ἄστρον "star", and physis, φύσις "nature") is the branch of astronomy that deals with the physics of the universe, especially with "the nature of the heavenly bodies, rather than their positions or motions in space.
"[1][2] Among the objects studied are galaxies, stars, planets, extrasolar planets, the interstellar medium and the cosmic microwave background.[3][4] Their emissions are examined across all parts of the electromagnetic spectrum, and the properties examined include luminosity, density, temperature, and chemical composition. Because astrophysics is a very broad subject, 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.