terça-feira, janeiro 09, 2007

O Esqueleto do Cosmos

A matéria escura é exótica

A sampling of famous astronomers

Astronomer Contribution

Hipparchus and Ptolemy Determined the positions of about 1,000 bright stars, tried to explain the puzzles of astronomy without refuting the geocentric model of universe and classified stars by magnitude.

Aristarchus of Samos First known person to propound the heliocentric model of universe. Attempted to calculate the sizes and distances of the Sun and Moon.

Nasir al-Din al-Tusi This Persian astronomer gave the first extant exposition of the whole system of plane and spherical trigonometry. Made very accurate tables of planetary movements and named many stars. Developed the Tusi-couple which resolves linear motion into the sum of two circular motions. He also calculated the value of 51' for the precession of the equinoxes and contributed to construction and usage of astrolabe.

Nicolaus Copernicus First exponent of heliocentrism in modern times.

Tycho Brahe Did develop many important astronomical instruments, and achieved accurate measurments of the heavens by improving scentific methodology and by designing instruments on a large scale. His measurements of the orbit of Mars were very important to the development of astronomy.

Johannes Kepler Suggested the elliptical orbits of planets, and propounded his Laws of Planetary Motion.

Galileo Galilei Was the first to use the telescope to observe the sky. Condemned to house arrest for his discoveries by Inquisitional edict, which was lifted 359 years later by Pope John Paul II.

Jeremiah Horrocks First to observe the transit of Venus, he also improved estimates of the distance of the sun from the earth and the size of Venus and other planets. Also correctly showed that the moon's orbit was elliptical, and suggested influence on its orbit from the sun as well as the earth.

Isaac Newton Published Philosophiae Naturalis Principia Mathematica (1687), containing the "Newton's laws of motion", which are fundamental to mechanical physics, and which explained Kepler's laws of planetary motion. Predicted the orbits of the planets.

Subrahmanyan Chandrasekhar Extensive work on the internal mechanisms of stars, particularly known for determining the effect of special relativity on stars, including being the first to calculate the Chandrasekhar limit, which he did, without a calculator, on a boat journey.

Henrietta Swan Leavitt Catalogued Cepheid variable stars in the Magellanic Clouds, in 1912 discovered the relationship between luminosty and periodicity in Cepheids -- leading to Hertzsprung's later work.

Ejnar Hertzsprung Determined the distance to several Cepheids, when Cepheids were detected in other galaxies such as the Andromeda galaxy, the distance to those galaxies could then be determined.

Edwin Hubble Discovered the expansion of the universe. (Hubble's Law) The Hubble Orbiting Space Telescope was named in his honor.


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