John N. Bahcall

born 1934-present

In the 1960s Bahcall began to consider the emission of neutrinos from the Sun. One of the apparent early triumphs of nuclear physics was the light it threw on the internal workings of the Sun. Theorists such as Hans Bethe had proposed the existence of a number of cyclic fusion reactions producing vast amounts of energy, heavier elements, and a certain number of neutrinos. As neutrinos have a low probability of interacting with other particles, some solar neutrinos should be received at the Earth's surface. Bahcall calculated that one event per second for every 10³⁶ target atoms, one solar neutrino unit (SNU), should be detectable. The matter was put to the test by Ray Davis who used a detector consisting of a tank of 100,000 gallons of cleaning fluid in a one-mile-deep mine.
http://www.answers.com/topic/john-noris-bahcall

s.chandrasekhar

born 1910- died 1995
Indian astrophysicist who studied at Cambridge, then moved to America and the University of Chicago. He has contributed significantly to many disparate branches of physics, including rotational figures of equilibrium, stellar interiors, black holes, radiative transfer, hydromagnetic stability, stellar dynamics, and many others. Chandrasekhar's name is immortalized in connection with the Chandrasekhar limit, which is the largest mass a white dwarf can attain. The theory underlying this result was viciously attacked by Eddington, who used nonsensical and contradictory arguments to try to show it invalid. Chandrasekhar wrote in a letter home "The differences are of a 'political' nature. http://scienceworld.wolfram.com/biography/Chandrasekhar.html

Arno Penzias

born 1933 - to present

In 1964, on building their most sensitive antenna/receiver system, Penzias and Wilson encountered radio noise that they could not explain. It was far less energetic than the radiation given off by the Milky Way, and it was isotropic, so they assumed their instrument was subject to interference by terrestrial sources. They tried, and then rejected, the hypothesis that the radio noise emanated from New York City. An examination of the microwave horn antenna showed it was full of pigeon droppings (which Penzias described as "white dielectric material"). After the pair removed the guano buildup, and the pigeons were shot (each physicist says the other ordered the deed), the noise remained. Having rejected all sources of interference, the pair published a paper announcing their findings. This was later identified as the cosmic microwave background radiation (CMB), the radio remnant of the Big Bang. This allowed astronomers to confirm the Big Bang, and to correct many of their previous assumptions about it.
http://www.jewishvirtuallibrary.org/jsource/biography/Penzias.html
]

Annie Cannon

born 1863-died 1941

Cannon also published catalogs of variable stars (including 300 she discovered). Her career spanned more than forty years, during which women in science won grudging acceptance. She received many "firsts" (first recipient of an honorary doctorate from Oxford, first woman elected an officer of the American Astronomical Society, etc.). At Harvard she was named Curator of Astronomical Photographs, but it was only in 1938, two years before her retirement, that she obtained a regular Harvard appointment as William C. Bond Astronomer.
http://www.sdsc.edu/ScienceWomen/cannon.html

Clyde Tombaugh

born 1906 - died 1997

Discoverer of dwarf planet Pluto
He used this telescope to make fine sketches of Mars and Jupiter, and sent the drawings to the Lowell Observatory, for comment (they are still there today), he was offered a job as an assistant. Tombaugh continued searching the skies at Lowell Observatory over the next 13 years, with time out for a college education. No more planets showed up, but he discovered six star clusters, two comets, hundreds of asteroids, several dozen clusters of galaxies and the super-cluster of galaxies stretching from Andromeda to Perseus. In 1932 he discovered a nova in Corvus that had exploded a year earlier.
http://www.oarval.org/tombaughen.htm

Johannes Kepler

born 1571 - died 1630

• First to investigate the formation of pictures with a pin hole camera;
• First to explain the process of vision by refraction within the eye;
• First to formulate eyeglass designing for nearsightedness and farsightedness;
• First to explain the use of both eyes for depth perception.
• First to describe: real, virtual, upright and inverted images and magnification;
• First to explain the principles of how a telescope works;
• First to discover and describe the properties of total internal reflection.http://kepler.nasa.gov/johannes/#anchor779268

Albert Einstein

born 1879 - died 1955
Albert Einstein wrote a paper with a new understanding of the structure of light. He argued that light can act as though it consists of discrete, independent particles of energy, in some ways like the particles of a gas. A few years before, Max Planck's work had contained the first suggestion of a discreteness in energy, but Einstein went far beyond this. His revolutionary proposal seemed to contradict the universally accepted theory that light consists of smoothly oscillating electromagnetic waves. But Einstein showed that light quanta, as he called the particles of energy, could help to explain phenomena being studied by experimental physicists. For example, he made clear how light ejects electrons from metals. He first gained worldwide prominence in 1919, when British astronomers verified predictions of Einstein's general theory of relativity through measurements taken during a total eclipse. Einstein's theories expanded upon, and in some cases refuted, universal laws formulated by Newton in the late seventeenth century." http://inventors.about.com/library/inventors/bleinstein.htm

Edwin Hubble

born 1889 - died 1953
Hubble wanted to classify the galaxies according to their content, distance, shape, and brightness patterns, and in his observations he made another momentous discovery: By observing redshifts in the light wavelengths emitted by the galaxies, he saw that galaxies were moving away from each other at a rate constant to the distance between them (Hubble's Law). The further away they were, the faster they receded. This led to the calculation of the point where the expansion began, and confirmation of the big bang theory. Hubble calculated it to be about 2 billion years ago, but more recent estimates have revised that to 20 billion years ago.
http://www.pbs.org/wgbh/aso/databank/entries/bahubb.html

Isaac Newton

born 1643 - died 1727

Isaac Newton was the greatest English mathematician of his generation. He laid the foundation for differential and integral calculus. His work on optics and gravitation make him one of the greatest scientists the world has known.
http://www-groups.dcs.st-and.ac.uk/~history/Mathematicians/Newton.html

Galileo Galilei

born 1564 - died 1642

Galileo Galilei was an Italian scientist who formulated the basic law of falling bodies, which he verified by careful measurements. He constructed a telescope with which he studied lunar craters, and discovered four moons revolving around Jupiter and espoused the Copernican cause.
http://www-groups.dcs.st-and.ac.uk/~history/Mathematicians/Galileo.html

Tycho Brahe

born 1546- died 1601
The appearance in 1572 of a "new star" (in fact a supernova) prompted Tycho's first publication, which was issued by a Copenhagen printer in 1573. In 1574, he gave some lectures on astronomy at the University of Copenhagen. Already he was of the opinion that the world-system of Copernicus was mathematically superior to that of Ptolemy, but physically absurd. In 1576, his permanent relocation to Basle, which he considered the most suitable place for him to continue his astronomical studies, was forestalled by King Frederick II, who offered him in fief the island of Hven in the Danish Sound. With generous royal support, Tycho constructed there a domicile and observatory which he called Uraniborg, and developed a range of instruments of remarkable size and precision which he used, with the aide of numerous assistants and students, to observe comets, stars, and planets. http://www.hps.cam.ac.uk/starry/tycho.html

Nicolas Copernicus

born 1473- died 1543
Copernicus is said to be the founder of modern astronomy. He was born in Poland,1 and eventually was sent off to Cracow University, there to study mathematics and optics; at Bologna, canon law. Returning from his studies in Italy, Copernicus, through the influence of his uncle, was appointed as a canon in the cathedral of Frauenburg where he spent a sheltered and academic life for the rest of his days. Because of his clerical position, Copernicus moved in the highest circles of power; but a student he remained. For relaxation Copernicus painted and translated Greek poetry into Latin.http://www.blupete.com/Literature/Biographies/Science/Copernicus.htm

Henrietta Leavitt

born 1868 -died 1921
As a senior in 1892, Leavitt discovered astronomy. After graduation she took another course in it, but then spent several years at home when she suffered a serious illness that left her severely deaf. She hadn't forgotten about astronomy, though. She volunteered at the Harvard College Observatory in 1895. Seven years later she was appointed to the permanent staff (at a salary of 30 cents an hour) by director Charles Pickering. She got little chance to do theoretical work, but did become head of the photographic photometry department. This group studied photo images of stars to determine their magnitude.http://www.pbs.org/wgbh/aso/databank/entries/baleav.html

James Van Allen

born 1914 died 2006
-developed the first plans for an International Geophysical Year (IGY); a coordinated, international, and comprehensive study of Earth for an 18-month period from July 1957 through December 1958. This first integrated study of Earth as a planet ushered in the space age by providing the model for large-scale, government-funded science, and because the United States and the Soviet Union included the first satellite launchings in their contributions. Van Allen's instruments were aboard the first successful American satellites, Explorers 1 and 3, launched in 1958, and provided data for the first space-age scientific discovery: the existence of a doughnut-shaped region of charged particle radiation trapped by Earth's magnetic field.
http://www.agu.org/inside/awards/vanallen.html

Albert Michelson

-born 1852 died 1931
-Michelson touched on many departments of physics but, perhaps due to a special instinct which he appeared to possess, he excelled in optics. He performed early measurements of the velocity of light with amazing delicacy and in 1881 he invented his interferometer for the purpose of discovering the effect of the Earth's motion on the observed velocity. In cooperation with Professor E.W. Morley, and using the interferometer, it was shown that light travels at a constant speed in all inertial systems of reference. The instrument also enabled distances to be measured with greater accuracy by means of the length of light-waves.
-http://nobelprize.org/nobel_prizes/physics/laureates/1907/michelson-bio.html

Pope Gregory XIII

-born 1502 died 1585
-However, he received the news of the massacre of St. Bartholomew (23rd of August 1572) with joy, and publicly celebrated the event, having been led to believe, according to his apologists, that France had been miraculously delivered, and that the Huguenots had suffered justly as traitors. Having failed to rouse Spain and Venice against the Turks, Gregory attempted to form a general coalition against the Protestants. He subsidized Philip II in his wars in the Netherlands; aided the Catholic League in France; incited attacks upon Queen Elizabeth I by way of Ireland. With the aid of the Jesuits, whose privileges he multiplied, he conducted a vigorous propaganda. He established or endowed above a score of colleges, among them the Collegium Romanum (founded by St. Ignatius of Loyola in 1550), and the Collegium Germanicum in Rome. Among his noteworthy achievements are the reform of the calendar on the 24th of February 1582; the improved edition of the Corpus juris canonici, 1582
http://www.nndb.com/people/130/000094845/

Stephen Hawking

Born 1942 and is still living
-devoted much of his life to probing the space-time described by general relativity and the singularities where it breaks down. And he’s done most of this work while confined to a wheelchair, brought on by the progressive neurological disease amyotrophic lateral sclerosis, or Lou Gehrig’s Disease
-http://www.pbs.org/wnet/hawking/cosmostar/html/hawking.html

Carl Sagan

-Born 1934 Died 1996
-He pioneered exobiology and promoted the Search for ExtraTerrestrial Intelligence (SETI). He is world-famous for his popular science books and the television series Cosmos, which he co-wrote and presented. In his works he frequently advocated the scientific method.
-http://www.crystalinks.com/sagan.html

Ptolemy

Born 85 Dided 165
-Ptolemy propounded the geocentric theory in a form that prevailed for 1400 years. However, of all the ancient Greek mathematicians, it is fair to say that his work has generated more discussion and argument than any other. We shall discuss the arguments below for, depending on which are correct, they portray Ptolemy in very different lights. The arguments of some historians show that Ptolemy was a mathematician of the very top rank, arguments of others show that he was no more than a superb expositor, but far worse, some even claim that he committed a crime against his fellow scientists by betraying the ethics and integrity of his profession.
-http://www-history.mcs.st-and.ac.uk/Biographies/Ptolemy.html

Hipparchus

Born 190 BC Died 120 BC
-Hipparchus' many important and lasting contributions to astronomy included practical and well as theoretical innovations. He employed geometrical models, including the deferent-epicycle and eccentric previously used by Apollonius (flourished ca. 200 B.C.). One of his contributions appears to have been the incorporation of numerical data based on observations into the geometrical models developed to account for the astronomical motions
-http://www.hps.cam.ac.uk/starry/hipparchus.html

Aristotle

384-322 BCE
-Aristotle probably represent only a fragment of the whole, they include his investigations of an amazing range of subjects, from logic, philosophy, and ethics to physics, biology, psychology, politics, and rhetoric. Aristotle appears to have thought through his views as he wrote, returning to significant issues at different stages of his own development.
-http://www.philosophypages.com/ph/aris.htm