Historical Figures to Remember Flashcards
(16 cards)
Hipparchus
Compiles the first-star catalog in the western world and he compared the brightness of the stars
Remember: He’s hip, with the times. Hip hop western music. Model
Eratosthenes
Had read of well at Syene, at noon on midsummer’s day he knew the sun shone directly down the well. But north, in Alexandria at the same time, Eratosthenes observes a column casting a shadow of seven degrees. Using the discrepancy, Eratosthenes proved the earth was round, and simple geometry gave him the circumference
Remember: Syene and ene in his name
Nicolaus Copernicus
Resurrected the theory of planets orbiting the sun
His heliocentric system put the Sun (helio) at the center of our system. He was not the first to have this theory. Earlier starwatchers had believed the same, but it was Copernicus who brought it to the world of the Renaissance and used his own observations of the movements of the planets to back up his idea. His ideas, including the revelation that the Earth rotates on its axis, were too different for most of the scholars of his time to accept. They used only parts of his theory. Those who did study his work intact often did so in secret. They were called Copernicans.
Remember: the earth go aroundicus the sun
Tycho Brahe
Known for his accurate and comprehensive observations without a telescope
Remember: Bravo Tycho
Johannes Kepler
Defined three laws of planetary motion:
1) Planets move around the sun in ellipses, not circles
2) Orbital speed varies, the planet travels fastest when nearest the sun and slowest when farthest away
3) Planets orbit slower and slower the more distant they are from the sun. Explains retrograde loops (when a planet appears to go in a loop from another planet due to another planet overtaking it due to a smaller orbit)
Remember: Kepler telescope orbiting earth
Galileo Galilei
Found:
- Moons around Jupiter
- Craters on our moon
- Saw the faces of Venus and angered the church with his sun center views
- Moons of Jupiter (4 Galilean moons)
- Rings of Saturn
- Surface structures on the moon, first estimates of the height of mountains on the moon
- Sunspots
- Phases of Venus (proving it orbits the sun, not the Earth)
Isaac Newton
- Split sunlight into the colours of the rainbow (a spectrum)
- Developed the reflecting telescope, using mirror rather than lenses, to collect and focus light
- Worked out gravity
Imagine: Isaac Newton, sitting under an apple tree, pink Floyd shirt and telescope
William Herschel
Discovered the planet Uranus
Through a telescope he built, he mapped out the milky way, he deduced it was the sideways view of a galactic disk
Infrared light
Remember: Looks like a deer in headlights when he sees Uranus, Hershey’s milk chocolate
Karl Jansky
Founded radio astronomy
Jacobus Kapteyn
Most known for measuring the size of the milky way
Through:
Parallax: find the distances of nearby bright stars
Proper motion: stars appear to move relative to other stars
Remember: Captain of the voyage to find the size of the milky way
Harlow Shapley
Mapped the distribution of globular clusters
(Globular clusters are densely packed collections of ancient stars. Roughly spherical in shape, they contain hundreds of thousands, and sometimes millions, of stars. Studying them helps astronomers estimate the age of the universe or figure out where the center of a galaxy lies)
- obtained distances from RR Lyrae variables
- Gets distance wrong but shape right
Remember: Shape - Shapley
The great debate:
Harlow Shapley
Nebulae are “local”
Shapley argued that the universe was comprised of a single galaxy
Curtis thought that the spiral nebulae were galaxies external to our own, while Shapley disagreed, holding instead that they were clusters made up mostly of gas. On this point, Curtis turned out to be correct, as subsequent data bore out. But Shapley was correct in arguing that our galaxy was larger than previously thought, and for showing that our Sun was not at the center of its galaxy.
The great debate:
Heber D. Curtis
Nebulae are galaxies
Curtis held that it contained many galaxies.
Curtis thought that the spiral nebulae were galaxies external to our own, while Shapley disagreed, holding instead that they were clusters made up mostly of gas. On this point, Curtis turned out to be correct, as subsequent data bore out. But Shapley was correct in arguing that our galaxy was larger than previously thought, and for showing that our Sun was not at the center of its galaxy.
Henrietta Swan Leavitt
This work led her to discover the relation between the luminosity and the period of Cepheid variables. Leavitt’s discovery provided astronomers with the first “standard candle” with which to measure the distance to faraway galaxies.
Cepheid variables: important because it was known that the time it took them to pulse was directly related to their luminosity, how much energy they emitted.
That means if you can measure their period, you can determine how far away they are simply by measuring their apparent brightness.
Remember: glowing white swan
Aristotle
No parallax of stars means they are far away
Remeber: Aristotle tattled about no parallax
Ptolomy
the study of complex planetary motion
Epicycle theory prediction of planetary motion including eclipses
