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

    Dec 19, 2025 · Astronomy, science that encompasses the study of all extraterrestrial objects and phenomena. Since the late 19th century, astronomy has expanded to include astrophysics, the …

  2. Astronomy Definition & Meaning | Britannica Dictionary

    ASTRONOMY meaning: the scientific study of stars, planets, and other objects in outer space

  3. astronomy - Kids | Britannica Kids | Homework Help

    The study of astronomy involves all of the objects outside Earth’s atmosphere. These include the Sun, Moon, planets, stars, galaxies, and all other matter in the universe.

  4. Astronomy Portal | Britannica

    Astronomy, science that encompasses the study of all extraterrestrial objects and phenomena. Until the invention of the telescope and the discovery of the laws of motion and gravity in the …

  5. Definition, Planets, Diagram, Videos, & Facts - Britannica

    Jan 3, 2026 · The Sun, Moon, and brightest planets were visible to the naked eyes of ancient astronomers, and their observations and calculations of the movements of these bodies gave …

  6. Astronomy - Techniques, Observations, Measurements | Britannica

    Dec 19, 2025 · Astronomy - Techniques, Observations, Measurements: Astronomical observations involve a sequence of stages, each of which may impose constraints on the type …

  7. History of astronomy and contributions of Ptolemy, Nicolaus …

    astronomy, Science dealing with the origin, evolution, composition, distance, and motion of all bodies and scattered matter in the universe. The most ancient of the sciences, it has existed …

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

    3 days ago · The rate at which galaxies and large structures composed of galaxies coalesced from density fluctuations in the early universe indicates that the nonbaryonic dark matter is …

  9. astronomy - Students | Britannica Kids | Homework Help

    Before the dawn of history someone noticed that certain celestial bodies moved in orderly and predictable paths, and astronomy—an ancient science—was born. Yet some of science’s …

  10. Astronomy - Ancient, Celestial, Observations | Britannica

    Dec 19, 2025 · Astronomy - Ancient, Celestial, Observations: Astronomy was the first natural science to reach a high level of sophistication and predictive ability, which it achieved already …