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    Timelines – Astronomical discoveries

    Time PeriodDiscoveryDescription
    Ancient TimesCelestial ObservationPeople in ancient civilizations observed the skies, recognized patterns and stars. They noted the movement of celestial objects, identified constellations, and tracked celestial events.
    Era of Early AstronomyPlanets and Moon PhasesAncient Greeks and other early astronomers distinguished between stars and planets (“wanderers”), noted planets’ retrograde motion, and understood lunar phases.
    Middle AgesAstrolabeThe Astrolabe, a sophisticated tool used to measure the position of celestial bodies and to navigate, was refined. It greatly enhanced accuracy in astronomical observation.
    Renaissance PeriodHeliocentric ModelCopernicus proposed the Heliocentric Model, where the sun is the center of the solar system. This challenged the prevailing geocentric belief.
    Early Modern PeriodTelescope InceptionThe telescope was invented, leading to a dramatic increase in the precision of astronomical observations. Galileo made many discoveries, including the moons of Jupiter.
    18th CenturyUnderstand GravityIsaac Newton developed the law of universal gravitation, which explained the orbits of planets and their moons, laying the foundation for modern physics.
    19th CenturySpectroscopyThe science of spectroscopic measurement and analysis was developed, allowing astronomers to determine the composition of celestial bodies.
    Early 20th CenturyGalaxy IdentificationBefore the 20th century, the Milky Way was believed to be the entire universe. The discovery of other galaxies expanded our understanding of the universe’s size.
    Mid 20th CenturyExpansion of the UniverseEdwin Hubble’s observations led to the understanding that our universe is expanding, which is a fundamental part of the Big Bang model of cosmology.
    Late 20th CenturyCosmic Microwave Background RadiationThe discovery of the cosmic microwave background radiation provided strong evidence for the Big Bang theory.
    Early 21st CenturyExoplanets Orbiting other StarsThe first exoplanets were discovered orbiting other stars in our galaxy, leading to speculation about potential life on other planets.
    CurrentGravitational WavesThe direct detection of gravitational waves confirmed a major prediction of Einstein’s general theory of relativity, opening up new ways of observing the universe.