Astronomer · 1564 CE – 1642 CE

Galileo Galilei

History of AstronomyThe Scientific Revolution

Biography

Galileo Galilei turned the newly invented telescope to the sky in 1609 and changed astronomy forever. He found four moons circling Jupiter, mountains on the Moon, countless stars in the Milky Way, and the phases of Venus — direct evidence against the geocentric model. Condemned by the Inquisition in 1633, he is remembered as a founder of observational science.

Scientific contributions

Pioneered telescopic astronomy (1609–1610)
Discovered the four large moons of Jupiter
Observed the phases of Venus, supporting heliocentrism

Major discoveries

Major publications

Observatories, instruments & objects

Knowledge connections

DiscoveredIo
DiscoveredEuropa
DiscoveredGanymede
DiscoveredCallisto
Influenced byNicolaus Copernicus
Part ofThe Scientific Revolution
ObservedJupiter
ObservedVenus
ObservedThe Moon
ObservedIo
ObservedEuropa
ObservedGanymede
ObservedCallisto
DiscoveredThe Galilean Moons of Jupiter
DiscoveredThe Phases of Venus
PublishedSidereus Nuncius
PublishedDialogue Concerning the Two Chief World Systems
Associated withInstrumentation-Driven Discovery
Associated withThe Copernican Revolution
Associated withThe History of the Telescope

Sources & references

Facts on this topic will be cited from these primary and reference sources.

BritannicaEncyclopaedia Britannica
General reference for the history of astronomy, biographies, and cultural context.
IAUInternational Astronomical Union
Official naming, definitions, constellation boundaries, and astronomical nomenclature.

Quick facts

Lifespan: 1564 CE – 1642 CE
Nationality: Italian
Era: The Scientific Revolution
Fields: Astronomy, Physics
Institutions: University of Padua; Florence
Discoveries: 2
Publications: 2

Quality & authority

56%

Reviewed

Completeness: Complete
Source coverage: Partial
Citation coverage: Complete
Relationship coverage: Complete
Review coverage: Complete
Image coverage: None

Curated from authoritative reference sources. See source quality.

Provenance & sources

review 2026.1

Asteria Scientific Review Process · verification: sourced · accurate

Historical evidenceconfirmed
Galileo Galilei made pioneering telescopic observations in 1609–1610, including the four large moons of Jupiter, the phases of Venus, and craters on the Moon, supporting the heliocentric model.
Source: Encyclopaedia Britannica

Reviewed by the internal Asteria Scientific Review Process — not an external institutional review. See the evidence framework and authority dashboard.

Scientific citations

Real, source-backed references — primary papers first, then datasets and institutional sources. Formatted through the citation engine; nothing is fabricated.

Historical referenceGalileo Galilei — Encyclopaedia Britannica

Encyclopaedia Britannica

Cite (APA / BibTeX)

Encyclopaedia Britannica (n.d.). Galileo Galilei — Encyclopaedia Britannica. Encyclopaedia Britannica. https://www.britannica.com/biography/Galileo-Galilei

@misc{cite:britannica-astronomer-galileo-galilei,
  title        = {Galileo Galilei — Encyclopaedia Britannica},
  organization = {Encyclopaedia Britannica},
  year         = {n.d.},
  url          = {https://www.britannica.com/biography/Galileo-Galilei},
  note         = {Biographical and background reference for Galileo Galilei (secondary source).}
}

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Biography

Sources & references

Facts on this topic will be cited from these primary and reference sources.

BritannicaEncyclopaedia Britannica

General reference for the history of astronomy, biographies, and cultural context.

IAUInternational Astronomical Union

Official naming, definitions, constellation boundaries, and astronomical nomenclature.

Encyclopaedia Britannica (n.d.). Galileo Galilei — Encyclopaedia Britannica. Encyclopaedia Britannica. https://www.britannica.com/biography/Galileo-Galilei @misc{cite:britannica-astronomer-galileo-galilei, title = {Galileo Galilei — Encyclopaedia Britannica}, organization = {Encyclopaedia Britannica}, year = {n.d.}, url = {https://www.britannica.com/biography/Galileo-Galilei}, note = {Biographical and background reference for Galileo Galilei (secondary source).} }