astrolabe, any of a type of early scientific instrument used for reckoning time and for observational purposes. One widely employed variety, the planispheric astrolabe, enabled astronomers to calculate …

astrolabe, Type of early scientific instrument used for reckoning time and for observational purposes. Astrolabes can be traced to the 6th century ad; they came into wide use in Europe and the Islamic …

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 in the second half …

Learn about the history of astronomy and the significant contributions of Ptolemy, Nicolaus Copernicus, and Isaac Newton The Editors of Encyclopaedia 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 …

Celestial navigation, use of the observed positions of celestial bodies to determine a navigator’s position. At any moment some celestial body is at the zenith of any particular location on the Earth’s surface. …

Humankind's fascination with the world beyond Earth has led to many landmark moments in history, as when space exploration took a giant step forward with the advent of technology that allowed humans …

Dec 19, 2025 · Astronomy - Ancient Greece, Stars, Planets: Astronomy is present from the beginning of Greek literature. In Homer’s Iliad and Odyssey, stars and constellations are mentioned, including …

Dec 19, 2025 · A key theoretical development for 20th-century astronomy and cosmology was the development of the theory of relativity, from 1905 to 1915, which eventually led to an explanation of …

Dec 19, 2025 · Astronomy - Solar System, Planets, Stars: The solar system took shape 4.57 billion years ago, when it condensed within a large cloud of gas and dust. Gravitational attraction holds the …