History of Astronomy (with Eras & Centuries)
1. Ancient Astronomy (Stonehenge, Babylon, Egypt, Greek geocentrism – up
to 2nd century CE)
Humanity’s earliest sky watchers—from alignments at Stonehenge (~3000 BCE), to
Babylonian planetary records (~1800 BCE), to Egypt’s star-based calendars—laid the
foundations of astronomy. In the 2nd century CE, Claudius Ptolemy formalized the
geocentric model in The Almagest, asserting Earth at the universe’s center—a view that
reigned for over 1,400 years Flickr+3Star Walk+3Mindomo+3.
2. Islamic Golden Age (8th–14th centuries)
Islamic scholars translated Greek works and built advanced observatories in Maragha and
Samarkand. Al-Battānī refined astronomical measurements; Ibn al-Shātir improved Ptolemaic
models in the 14th century—some reflecting ideas later echoed in Copernicus
Encyclopedia.comEncyclopedia Britannica.
3. Copernican Revolution (16th century)
In 1543, Nicolaus Copernicus published De revolutionibus orbium coelestium, introducing a
heliocentric solar system—Sun-centered orbits replaced Earth-centered models and launched
the scientific revolution Encyclopedia BritannicaEncyclopedia BritannicaEncyclopedia
Britannica.
4. Galileo & Kepler (17th century)
Galileo Galilei’s telescopic observations around 1610—Jupiter’s moons, Venus’s phases,
lunar surface—supported heliocentrism Encyclopedia BritannicaEncyclopedia Britannica.
Johannes Kepler (1609) derived his three laws—elliptical orbits, area law, and harmonic law
—revealing how planets move around the Sun Encyclopedia BritannicaEncyclopedia
BritannicaEncyclopedia Britannica.
5. Isaac Newton (late 17th century)
Newton’s Principia (1687) introduced universal gravitation and laws of motion,
mathematically explaining Kepler’s findings and unifying celestial and terrestrial physics
Encyclopedia BritannicaEncyclopedia BritannicaEncyclopedia Britannica.
6. 18th–19th Century: Discovery & Spectroscopy
William Herschel discovered Uranus in 1781, marking the first new planet found in modern
times; Neptune followed in 1846. These centuries also saw spectroscopy and photography
revolutionizing star classification and composition studies Encyclopedia
BritannicaEncyclopedia BritannicaEncyclopedia Britannica.
7. 20th Century: Modern Cosmology & Exploration
1924: Edwin Hubble proved that the “spiral nebulae” are other galaxies. In 1929, he
formulated Hubble’s Law—galaxies receding faster at greater distances—implying an
expanding universe wired.comEncyclopedia BritannicaEncyclopedia BritannicaEncyclopedia
Britannica. Georges Lemaître proposed the Big Bang origin theory, and advances followed in
radio astronomy, exoplanet detection, dark matter/energy, and space missions. Stephen
Hawking’s work on black holes and quantum cosmology shaped modern physics, along with
A Brief History of Time illuminating public understanding time.comtime.com.
Timeline of Key Events & Eras
Year / Era Era / Century Key Event & Figure
~3000 BCE Ancient Stonehenge astronomical alignment
~1800 BCE Ancient Babylonian planetary observations
2nd century CE Greek / Ptolemaic Ptolemy’s geocentric model
8th–14th century Islamic Golden Age Al-Battānī, Ibn al-Shātir (Maragha reforms)
1543 16th century Copernicus publishes heliocentric theory
~1610 17th century Galileo’s telescopic discoveries
1609 17th century Kepler’s planetary laws
1687 17th century Newton’s Principia published
1781 18th century Herschel discovers Uranus
1846 19th century Discovery of Neptune
1924 20th century Hubble identifies galaxies outside Milky Way
1929 20th century Hubble’s Law: universe expansion
1930s–1960s 20th century Lemaître’s Big Bang, radio astronomy
1974–present 20th–21st century Hawking, exoplanets, dark matter & energy
1990–present 21st century Space telescopes (HST), planetary missions
🧠 Mind-Map Image of Astronomy History
[Mind map showing eras branching from central topic “History of Astronomy”: Ancient →
Islamic → Copernican → Galileo/Kepler → Newton → 18th–19th → Modern. Each node
includes key figures/discoveries.]
🎥 Recommended Educational Video
A great illustrated overview of astronomy’s history and cosmic discovery is the official trailer
of Cosmos: A Spacetime Odyssey hosted by Neil deGrasse Tyson:
https://www.youtube.com/watch?v=3OaXrKzl2kc
📚 Suggested Additional Resources
Books: Cosmos (Carl Sagan), A Brief History of Time (Stephen Hawking), The
Copernican Revolution (Thomas Kuhn), A Short History of Nearly Everything (Bill
Bryson).
Documentaries: Cosmos (Sagan & Tyson), How the Universe Works.
Online Courses: Khan Academy’s astronomy series.
Observatory info: NASA, ESA, Space Telescope Science Institute (STScI).
