The Seven Giants

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These seven pioneers have had the greatest influence in shaping mankind's World View of our place in the Cosmos.

(Note: An epihany is the sudden, intuitive understanding of the reality or nature of something profound.)

Nicolaus Copernicus

Copernicus (1473:1543)

Proposed a heliocentric (Sun-centered) solar system to replace the geocentric (Earth-centered) system of Ptolemy. Was right about order of planets and distance from Sun. But was wrong about shape and mechanism of orbits.

Epiphany:Between 1503 and 1514
(age: between 30 and 41)
Published:Revolutions of the
Heavenly Spheres

Johannes Kepler

Kepler (1571:1630)

Developed three laws of planetary motion–Orbits are ellipses with Sun at one focus; Distance from Sun is proportional to orbital period; A planet sweeps out equal areas in equal times. Explained retrograde motion of planets.

Epiphany:1605 (age: 34)
Published:New Astronomy (1609) &
Harmony of the Worlds (1619)

Isaac Newton

Newton (1642:1727)

Created one law of gravity (proportional to mass of bodies and square of distance) and three laws of motion–Inertia at rest and in motion; Force equals mass times acceleration; Equal and opposite actions). Invented calculus to make computations.

Epiphany:1666 (age: 24)
Published:Mathematical Principles of
Natural Philosophy

Albert Einstein

Einstein (1879:1955)

Author of Special Relativity and General Relativity–Speed of light constant; Time, motion, mass, size all relative; Gravity and acceleration equivalent; Mass curves space and time. Created famous equation relating energy, mass, speed of light: E = m × c².

Epiphany:1907 (age: 28)
Published:Electrodynamics of Moving Bodies
[Special Relativity] (1905) &
Foundation of the General Theory
of Relativity

Harlow Shapley

Shapley (1885:1972)

Least known of giants. Found position of Sun in Milky Way galaxy (in one of spiral arms near edge of the Galaxy). Thought Galaxy is ten times larger than believed at the time. But over-stated distance from Sun to center by two-thirds.

Epiphany:1915 (age: 30)
Published:Globular Clusters and the Structure
of the Galactic System

Edwin Hubble

Hubble (1889:1953)

Determined location of Milky Way in Universe. Spiral nebula actually other galaxies outside of Milky Way. Found other galaxies move away from our Galaxy proportional to distance. But grossly under-estimated distances to other galaxies.

Epiphany:1925 (age: 35)
Published:Cepheids in Spiral Nebulae (1925) &
Relation between Distance
and Radial Velocity ...

Hannes Alfvén

Alfvén (1908:1995)

Father of the Plasma Universe–orphan of the astrophysical elite. His ideas reached from his laboratory to Earth's magnetosphere, to the Sun (sun-spots, solar flares, solar wind, cosmic rays), to the Milky Way galaxy, and to the entire (Plasma) Universe.

Epiphany:1939 (age: 31)
Published:Theory of Magnetic Storms
and the Aurorae
Electricity in Space (1948);
Cosmic Electrodynamics (1963);
Cosmic Plasma (1981)

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