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  1. astrophysics - Students | Britannica Kids | Homework Help

    The branch of astronomy called astrophysics is a new approach to an ancient field. For centuries astronomers studied the movements and interactions of the sun, the moon, planets, stars, …

  2. Physics | Definition, Types, Topics, Importance, & Facts | Britannica

    Oct 13, 2025 · Physics is the branch of science that deals with the structure of matter and how the fundamental constituents of the universe interact. It studies objects ranging from the very small …

  3. Astrophysics | Astronomy, Cosmic Objects, & Space | Britannica

    astrophysics, branch of astronomy concerned primarily with the properties and structure of cosmic objects, including the universe as a whole. See astronomy. The Editors of Encyclopaedia …

  4. Astrophysics Definition & Meaning | Britannica Dictionary

    ASTROPHYSICS meaning: the scientific study of the physical and chemical properties and structures of stars, planets, and other objects in outer space

  5. Dark matter | Definition, Discovery, Distribution, & Facts | Britannica

    Nov 29, 2025 · The precise nature of these particles is not currently known, and they are not predicted by the standard model of particle physics. However, a number of possible …

  6. Redshift | Definition & Facts | Britannica

    Nov 21, 2025 · Astronomy and Astrophysics - Re-evaluating the cosmological redshift: Insights into inhomogeneities and irreversible processes University of Iowa - Department of Physics …

  7. Astronomy | Definition, History, Discoveries, & Facts | Britannica

    Nov 14, 2025 · Since the late 19th century, astronomy has expanded to include astrophysics, the application of physical and chemical knowledge to an understanding of the nature of celestial …

  8. Space-time | Definition & Facts | Britannica

    Nov 11, 2025 · The universe according to this convention was called Newtonian. In a Newtonian universe, the laws of physics would be the same in all inertial frames, so that one could not …

  9. Gravitational constant | Definition, Value, Units, & Facts | Britannica

    Nov 14, 2025 · Although Isaac Newton is well known for his discoveries in optics (white light composition) and mathematics (calculus), it is his formulation of the three laws of motion —the …

  10. Physical science | Definition, History, & Topics | Britannica

    As it developed in the 20th century, physics is concerned with the structure and behaviour of individual atoms and their components, while chemistry deals with the properties and reactions …