Formal & Natural Sciences
Everything above the atmosphere: what is out there, how it got there, and how we get to it.
9 fields · 92 topics · 109 curated works
The instruments and techniques that turn photons into data.
Foundations & Overviews · Telescope Design · Photometry · Astronomical Spectroscopy · Astrometry
The bodies of our own solar system, in detail.
Foundations & Overviews · Terrestrial Planets · Gas & Ice Giants · Planetary Moons · Asteroids & Comets
How stars work, and how they die.
Foundations & Overviews · Stellar Structure · Stellar Evolution · Stellar Nucleosynthesis · Star Formation
Structure above the scale of single stars.
Foundations & Overviews · Structure of the Milky Way · Galaxy Morphology · Galaxy Formation & Evolution · Active Galactic Nuclei
The universe as a single object with a history.
Foundations & Overviews · Big Bang Cosmology · Cosmic Microwave Background · Cosmic Inflation · Dark Matter
Planets around other stars — a field that did not exist before 1992.
Foundations & Overviews · Detection Methods · Transit Photometry · Radial Velocity Method · Hot Jupiters
Whether life is a cosmic accident or a cosmic tendency.
Foundations & Overviews · Origin of Life · Extremophiles · Biosignatures · The Drake Equation
The engineering and politics of leaving the planet.
Foundations & Overviews · Orbital Mechanics · Launch Vehicles · Propulsion Systems · Spacecraft Design
How the sky was mapped, and how often we were wrong about it.
Foundations & Overviews · Ancient Astronomy · The Copernican Revolution · Galileo & the Telescope · Kepler's Laws
No prior grounding assumed.
A Short History of Astronomy
Arthur Berry · 1898
Surveys astronomy's development from Babylonian record-keeping to nineteenth-century stellar measurement, arguing progress came as much from improved…
+9 more at this level
Assumes you know the vocabulary.
On the Heavens
Aristotle · 350 BCE
Argues the cosmos is a finite set of concentric spheres turning about a stationary earth, with the heavens made of an unchanging fifth element…
+42 more at this level
Primary sources and full treatments.
De revolutionibus orbium coelestium
Nicolaus Copernicus · 1543
Argues, across six books of geometrical models, that a sun-centred and rotating-earth arrangement of the heavens accounts for planetary motion more…
+55 more at this level
12 of 109 works
Arthur Berry
Surveys astronomy's development from Babylonian record-keeping to nineteenth-century stellar measurement, arguing progress came as much from improved instruments and observational patience as from theoretical insight.
link checked 17 Sept 2026Svante Arrhenius
Proposes that microscopic spores are driven between star systems by radiation pressure alone, so life could spread through the galaxy without any vehicle or directing intelligence.
link checked 17 Sept 2026Walter W. Bryant
A short accessible account of Kepler's life arguing his three laws of planetary motion emerged from years of arithmetic struggle with Tycho Brahe's data rather than from any prior theoretical insight.
link checked 17 Sept 2026Arthur C. Clarke
Proposes that three satellites in the right orbit could relay radio and television to the whole planet, describing the geostationary communications satellite over a decade before one flew.
link checked 17 Sept 2026United States Congress
Establishes NASA and commits the United States to civilian, publicly disclosed control of space activity, deliberately separated from the military space programme housed in the Department of Defense.
link checked 17 Sept 2026United Nations General Assembly
Establishes that no state may claim sovereignty over the Moon or any celestial body and that outer space is to be used for peaceful purposes, the founding legal instrument every later space treaty rests on or reacts against.
link checked 17 Sept 2026Max Tegmark
Argues that four distinct, independently motivated levels of physical theory all predict some form of multiverse, so rejecting the idea outright is harder than it looks.
link checked 17 Sept 2026Frank Drake
The equation's author revisits it fifty years on, arguing that each term has moved from pure guesswork toward a measurable quantity as exoplanet and biosignature data accumulate.
Robert Dempsey
Written by the station's own flight directors, argues that operating a continuously crewed outpost is a distinct discipline from building one, won through routine and improvisation in Mission Control rather than by the original design.
link checked 17 Sept 2026Katie Mack (The Royal Institution)
Works through the physically possible endings of the universe — heat death, big rip, vacuum decay — and shows which are decided by the measured behaviour of dark energy.
link checked 17 Sept 2026Aristotle
Argues the cosmos is a finite set of concentric spheres turning about a stationary earth, with the heavens made of an unchanging fifth element distinct from the four terrestrial ones.
link checked 17 Sept 2026Johannes Kepler
Argues the spacing of the six known planetary orbits is fixed by nesting the five Platonic solids between them, offered as a physical reason why the Copernican system must be true rather than merely a convenient calculation.
link checked 17 Sept 2026