|
Al-Farghani, Alfraganus, Amateur Astronomer, Amateurs, Anders Angstrom, Arecibo Observatory, Asteroid Belt, Asteroid,
Astronomical, Astronomy, Atacama, Bernhard Schmidt, Big Horn Medicine Wheel, Black Hole, Bolide, Brian Timmins,
Brians Timelines, brianstimelines, CADC, Cahokia Mounds, Caltech, June 2000, Cambridge University,
Canadian Astronomy Data Centre, Carl Sagan, Carl Seyfert, Cerro Tololo Interamerican Observatory, Chaco Canyon,
Chandra Chankillo, Charles Messier, Chichen Itza, Chris Lintott, Christiaan Huygens, Chronological Facts, Chronological,
Chronology, Clyde Tombaugh, Comet, Copernicus, CTIO, DAO, Dark Matter, Dominion Astrophysical Observatory,
Dominion Radio Astrophysical Observatory, DRAO, Dwarf Planet, Earth, Edmond Halley, Edwin Hubble, Einstein, Ejnar Hertzsprung,
ESA, ESIS, ESO, European Southern Observatory, European Space Information System, Events, Fajata Butte, Fred Hoyle, Fritz Zwicky,
Galactic, Galaxy, Galileo Galilei, Galileo, Gemini, George Hale, Gerard Kuiper, Giovanni Cassini, GLAST, Goseck Circle,
Gravity Lens, Gravity Lensing, Gravity, Halley, Historical Event, History, HST Astrometry Science Team, Hubble,
Hypernova, Institute Of Astronomy And Royal Greenwich Observatory, Isaac Newton, James Van Allen, James Webb,
Jet Propulsion Laboratory, Johannes Kepler, Joseph Von Fraunhofer, Joseph-Louis Lagrange, JPL, Jupiter, Karl Schwarzchild,
Keplers Laws, Kitt Peak National Observatory, KPNO, Kuiper Belt, Las Campanas And Magellan, Las Campanas Observatory,
Light Year, Machu Picchu, Magellan Project, Mars, Mauna Kea, Mcdonald Observatory, Mercury, Meteor, Meteorite,
Meteoroid, Milky Way, MIT, Moon, Mount Stromlo And Siding Springs Observatories, Mount Wilson Observatory, MSO & SSO,
NASA, National Aeronautics And Space Administration, National Astronomy And Ionosphere Center,
National Observatory Of Japan, National Optical Astronomy Observatories, National Radio Astronomy Observatory,
National Solar Observatory, Nebula, Nebulae, Neptune, Neutron Star, Newgrange, Newton, Nicolaus Copernicus, Night Sky, NOAO,
Nova, NRAO, NSO, Observation, Observatories Of The Carnegie Institution Of Washington, Observatory, Oort Cloud, Parsec,
Patrick Moore, Planets, Pluto, Ptolemaiac, Ptolemaic, Ptolemy, Pulsar, Quark Star, Quasar, Royal Greenwich Observatory,
Sacramento Peak, SAO, Saturn, Search For Extra Terrestrial Intelligence, SETI, Sir Fred Hoyle, Sir Isaac Newton, Sir Patrick Moore,
Site, Sky At Night, Smithsonian Astrophysical Observatory, SOHO, Solar System, Space Telescope Electronic Information System,
Space Telescope Science Institute, Space, Spitzer, Stars, STEIS, Stephen Hawking, Stonehenge, STSCI, Subaru,
Subramanyan Chandrasekhar, Sunspot, Supernova, Gemini 8M Telescopes Project, Miami Circle, Temple At Karnak,
Very Large Telescope Project, Theory Of Relativity, Time Line, Time Scale, Time, Time-Lines, Timeline, Timelines, Timescale,
Timmins, Tycho Brahe, U.Mass Amherst, UKIRT, United Kingdom Infra-Red Telescope, University Of Massachusetts Astronomy,
University Of Texas Department Of Astronomy, Uranus, Ut-Austin, Venus, Virtual Observatory Conference, VLT,
Wallace Astrophysical Observatory, William Herschel, Woodhenge,
Lunar Distance, Astronomical Unit, Light Year, Parsec, Newton's Laws Of Motion, Solar Mass, Event Horizon,
Keplers Three Laws Of Planetary Motion, The Law Of Orbits, The Law Of Areas, The Law Of Harmonics, Singularity,
Newton's Law Of Gravitation, Hubble Constant, The Roche Limit, Schwarzchild Radius, Universal Gravitational Constant "G",
Abberation, Absorption Lines, Albedo, Aphelion, Apogee, Apparent Motion, Asteroid Belt, Azimuth And Elevation, Balmer Series,
Black Body Radiation, Black Hole, Bradley's Aberration, Chromosphere, Cherenkov Radiation, Comet, Corona, Coronal Hole,
Coronal Mass Ejection, CME, Declination, Eccentricity, Ecliptic, Epicycle, Equatorial Axis, Hohmann Orbit, Hydrogen Spectrum,
Klemperer Rosette, Kuiper Belt, Lagrangian Points, Libration, Luminance, Luminosity, Mach's Formulation, Mean Anomaly, Multiplet,
Neutron Star, Nodal, Nodal Month, Nutation, Nutation Cycle, Oblateness, Obliquity, Oort Cloud, Orbit, Orbital Elements,
Orbital Inclination, Orbital Motion Anomaly, Orbital Period, Parallax, Perhelion, Perigee, Perturbation, PHA,
Photosphere, Plane Of The Ecliptic, Precession, Precession Cycle, Primary, Primordial Microwaves, Prominence,
Retrograde Motion, Right Ascension And Declination, Semimajor, Sidereal Day, Sidereal Month, Sidereal Time, Sodium Spectrum,
Solar Activity, Solar Cycle, Solar Energetic Particles, Solar Flare, Solar Wind, Spectral Line, Stellar Evolution, Supernova,
Synodic, Synodic Period, Synodic Month, Transit, True Anomaly, Urca Process, Van Allen Radiation Belt, Zeeman Effect,
Achromatic Refractor, Apochromatic Refractor, Newtonian Reflector, Schmidt-Cassegrain, Maksutov-Cassegrain,
Schmidt-Newtonian, Maksutov-Newtonian, Dobsonian, Ritchey-Chretien, Adaptive And Multi Mirror Optics,
Huygenian Eyepiece, Ramsden Eyepiece, Kellner Eyepiece, Orthoscopic Eyepiece, Plossl Eyepiece, Wide Field Eyepieces,
Erfle Eyepiece, Konig Eyepiece, Nagler Eyepiece
 Thumbnail sketches of those men and women who though their efforts made astronomy the science it is today, both fascinating and practicable to professional and amateur alikeWhile the data are public domain, the entire textual content and layout of the articles on this page are Copyright
© Brian Timmins 2008, et seq. All rights reserved. Should you wish to use any of it for personal research or educative
purposes, you may make one hard copy for your own use without further permission or charge. Teachers and educationalists
may make as many copies as they need for classroom/lecture purposes - an eMail to say you are doing this would be appreciated.
|
Nicolaus Copernicus was born in Thorn, on the river Vistula, in Poland, on 19 February 1473. In 1491 Copernicus
entered the University of Crakow. Having finished his course at Crakow he moved to Italy and in 1500 he started
lecturing on astronomy at Rome. On noticing the inaccuracies of the Alfonsine Tables, began to formulate a new theory of
the position of the Sun, Moon and planets. He formulated several hypotheses:
Tycho Brahe was born in Denmark in 1546, the son of a Danish nobleman. His family sent him to study law at Leipzig
University, but Brahe was an enthusiastic astronomer and made secret nightly observations and studies of the science.
Brahe was convinced of the truth of astrological predictions and would often compile horoscopes. On 11 November 1572,
the appearance of a bright 'new star' or nova in the constellation Cassiopeia caught Brahe's attention. Brahe
immediately began observing the star and took many measurements of its brightness in comparison to that of other nearby
stars in Cassiopeia. Brahe built an observatory on the island of Hven, near Copenhagen and designed his own instruments
for use in it. His designs were a considerable improvement on previous designs. His instruments ranged from small,
hand-held quadrants to large devices with radii in excess of two metres which were able to measure positions to within
10 arcsec. Brahe used the equipment at his observatory to compile the most accurate star catalogue yet produced. It
superseded the catalogues of Hipparcus and Ptolemy that had lasted well over 1000 years. Brahe was not convinced by
Copernicus' heliocentric model of the Solar System, and with his numerous measurements of the positions of the planets,
he hoped to prove Copernicus wrong. History has a fine sense of irony as it was the accuracy of his observations which,
later in the hands of Kepler, revealed the truth of the heliocentric approach and showed the true structure of the Solar System.
Galileo Galilei was born in Pisa, Italy on 15 February 1564. He did well at school studying Medicine and Aristotelian
Philosophy and in September 1581 he entered the University of Pisa. Galileo became professor of mathematics at Pisa in
1589 at the age of 25. He propounded the novel theory that all falling bodies, heavy or light, fall to the Earth with
equal velocity. Legend has it that Galileo proved the point experimentally by dropping a hundred pound ball and a one
pound ball simultaneously from the top of the leaning Tower of Pisa. No contemporaneous account of the demonstration
exists, but Galileo recounted the story in his old age.
In 1592 Galileo achieved Professor of Mathematics at the University of Padua and his time there was a
happy one, making many discoveries. Most famously of all were great improvements to the design of the refracting
telescope. Unlike urban legend has it, he did not discover telescopes... he improved them.
Then, in 1610, Galileo began his serious astronomical investigations. His most powerful telescope being one
which gave a magnification of x32. He discovered that the Moon, instead of being self illuminating and smooth, had
an uneven surface marked with hills, valleys and mountains which cast shadows in the direction away from the Sun. He
could see, and described, the Milky Way as comprising countless thousands of stars. His series of observations of Jupiter
resulted in the discovery of the planet's four largest satellites - Io, Europa, Ganymede and Callisto - on 07 January 1610.
These four satellites are referred to collectively as the Galileans in his honour. He also discovered
sunspots and used them to estimate that the rotation period of the Sun was about twenty seven days.
His publicised belief in the heliocentric view of the Solar System of course, enraged the ecclesiastical authorities.
So they, at the instance of Pope Urban tried Galileo for his beliefs and he was forced to declare
a rebuttal in front of an Ecclesiastical Tribunal. As he was by now elderly and distinctly unwell,he
was not imprisoned but was forced to live the remaining
years of his life in retreat at a tiny village called Arcetri near Florence. He died in 1642 and is buried at
the church of Santa Croce in Florence.
Johannes Kepler was born at Weil-der-Stadt, Wurttemburg on 27 December 1571. He entered university at Tubingen where
he studied mathematics, astronomy and theology. In 1596, Kepler had his ideas on planetary orbits and distances
published, his explanation involving superimposing five regular polyhedra within the planetary orbits. In 1600, Kepler,
who by this time was working with Brahe in Prague, had been dismissed from his post at Gratz due to Catholic persecution
of Lutherans. Brahe died in 1601 and Kepler was appointed Mathematician to Emperor Rudolph II in his place.
Kepler's most important contribution to astronomy was his discovery of the three laws of planetary motion, which he
developed on the basis of Brahe's voluminous and accurate observations:
Giovanni Cassini was born at Perinaldo, Italy on 08 June 1625. He studied mathematics and astronomy at a Jesuit
college - his original reason for studying astronomy was said to be a desire to prove that astrology had no scientific
validity. In 1650 Cassini was offered the post of Professor of Astronomy at Bologna University; he accepted the offer
and held the position until 1669. While at Bologna, Cassini's main area of study was the Solar System. In 1665
and 1666 he determined the rotation periods of Jupiter and Mars. Two years later he published a table of the motions of
Jupiter's Galilean satellites: this table was later to help Roemer in his estimate of the speed of light (Roemer
presented his estimate, close to the currently accepted figure, to the French Academy of Sciences in 1675).
By 1669 Cassini's reputation was known throughout Europe to such an extent that Louis XIV invited him to become
director of the Paris Observatory where worked with Christian Huyghens He discovered four satellites of Saturn between
1671 and 1684 and discovered a division in Saturn's ring system which still bears his name. His most important work was
the determination of the parallax of Mars in 1672. Mars was observed from two locations: Paris and French Guiana. The
parallax of Mars was used to calculate the distance of Mars and since the relative distances of all the planets from the
Sun is known from Kepler's laws it was possible to calculate the size of the orbit of Mars.
Dutch mathematician, astronomer and physicist, born in The Hague. Studied law and mathematics at Leiden before turning
to science. Huygens was famous for his arguments that light consisted of waves. He was responsible for the development
of modern calculus. In 1655, he discovered Saturn's moon Titan. He also discovered that its rings consisted of rocks.
In the same year sketched the Orion Nebula. His drawing, the first such known of the Orion nebula, was published in "Systema
Saturnium" in 1659. Using a modern telescope he subdivided the nebula into different stars. The bright interior of the
Orion Nebula bears his name. He also discovered several interstellar nebulae and some double stars. Huygens formulated
what is now known as the second law of motion of Isaac Newton in a mathematical form which Newton reformulated and generalized.
He also devised a method of construction of extremely accurate clocks, usually called chronometers, which became indispensible
for naval navigation. He was elected a member of the Royal Society in 1663 and in 1666 Huygens moved to Paris where
he held a position at the French Academy of Sciences, where using the Paris Observatory he made many further astronomical
observations. Huygens returned to The Hague in 1681 after a serious illness. He tried to return to France in 1685 but a
resurgence of anti-Hugenot passions in France prevented this.
Isaac Newton was born in the year of Galileo's death. The son of a Lincolnshire farmer, he went up to Cambridge
University in 1661 to study mathematics. He made many contributions to mathematics and science, but his main
contribution to the science of astronomy was a mathematical understanding of the force of gravity that attracts all
objects in the universe. Newton returned home in 1665 and started work on the laws governing the motion of objects. He
wanted to define gravity in an exact mathematical manner. He also wished to understand how the force of gravity reduced
with increasing distance between bodies and to fit it in with the observed facts of planetary orbits.
Around this time, other scientists were also trying to understand lunar and planetary motions in terms of
a force of gravity, but the mathematics involved proved to be the main stumbling block. Edmund Halley while visiting
Newton in Cambridge discovered that Newton had worked out the solution and persuaded Newton to present his work to the
Royal Society. Newton presented his first paper in December 1684, and the pulication of the subsequent book "Principia"
was what most people consider to be the founding of moden astonomy. Newton also contributed two other important
innovations to astronomy. He discovered that white light was composed of colours that became visible when the light was
passed through a prism. Early refracting telescopes were hampered by chromatic aberration associated with their lenses;
Newton invented the reflecting telescope which relied on a mirror rather than an objective lens and thus avoided
chromatic aberration. He also deduced the three basic Laws of Motion. The word "genius" is over-used but here was one
of the towering geniuses of all time, mentionable in the same breath as Leonardo Da Vinci.
John Flamsteed was born at Danby in Derbyshire on 19 August 1646. At the age of 15, his poor health caused him to
leave school and led to the pursuit of his hobby, astronomy. He began to construct his own astronomical instruments, and
by 1670 received attention through the publication of several papers on astronomical topics. This in turn led Flamsteed
to become acquainted with Newton and to gain entrance to Cambridge University.
During the mid-seventeenth century, as a result of the need to produce accuate star charts for nagigational puposes
an observatory was built for Flamsteed, on a hill at Greenwich. Flamsteed had to equip the observatory with instruments
paid for with money from his own pocket assisted by whatever he could raise from friends and well-wishers. Flamsteed's
annual income was only £100 and by 1683 he had to supplement this by taking private pupils in astronomy and
mathematics.
Flamsteed was one of the first observers to use a telescope in combination with a graduated arc for measuring angles.
By 1703 he had completed more than 30,000 stellar positional measurements with a greater accuracy than had been achieved
before. The final version of Flamsteed's star catalogue did not appear until 1725, six years after his death. It
consisted of three volumes, the second two being completed by Abraham Sharp and Joseph Crossthwait. The catalogue gave
Greenwich an international reputation for precise observations that it has held ever since.
Edmond Halley is known nowadays by most people because of the periodic comet that bears his name. But he had a wide
range of scientific interests eventually became Astronomer Royal. Despite his not inconsiderable contribution to
astronomy, he was largely overshadowed by his friens and contemporary, Sir Isaac Newton - as indeed was everybody in
that era. He was born into a financially secure home at Haggerston, just outside London. He went to school at Saint
Pauls, and then on to Queen's College, Oxford where his interest in astronomy grew. At the age of 20, his university
degree incomplete, and having been influenced by John Flamsteed's Star Catalogue of the Northern Skies, Halley
decided to research the stars in the southern hemisphere. So he and a friend set off in November 1676 to sail to St.
Helena, in the south Atlantic, free passage having been ganted by the King on a ship of the East India Company. During
Halley's stay in St Helena, he observed a transit of Mercury on 7 November 1677 and measured the locations of some 360
stars. On his return, in 1679 he had these observations published as the Catalogus Stellarum Australium, which
contained detailed positions of 341 stars. The volume was widely acclaimed because not only was it the first catalogue
of the southern hemisphere stars but also the first mapping of stars compiled using a telescope. It established Halley's
scientific reputation, prompted Cambridge University to award him an honorary degree, and the Royal Society to elect him
a Fellow.
In 1679 Halley suggested that observations of a transit of Mercury or Venus across the Sun's disk could be
used to measure the size of the Sun and the scale of the Universe. He accurately calculated the dates of the transits of
Venus and predicted two of these, one in 1761 and the other in 1769. He worked with Sir Isaac Newton on the laws of
planetary motion and in 1685, Halley was elected Clerk to the Royal Society and started editing its journal,
Philosophical Transactions. As Halley could not get persuade the Royal Society to finance the publication of
Newton's work he financed the printing of the most famous scientific book of all time, Newton's Principia, being
published in 1687.
Halley discovered at this time were the differences between the orbits of Jupiter and Saturn and the slow
secular acceleration of the mean motion of the Moon. He did research into the Earth's magnetic field on behalf of The
Admiralty in the hope of discovering a reliable method of calculating longitude, and also discovered that the Aurora
Borealis was related to the Earth's magnetic field. He was one of the first astronomers to apply Newton's laws of
motion to comets. He postulated that the comets of 1456, 1531, 1607 and 1682 were the same, and that it would appear
again in 1758. Knowing he would not be alive to see it, he wrote the following in his diary: "If the Comet should return
according to my prediction, about the year 1758, impartial posterity will not refuse to acknowledge that this was
discovered by an Englishman". "Halley's Comet" returned as predicted and has done every 76 years since. During 1718
Halley observed Sirius, Aldebaran and Arcturus and compared their positions in the sky with Ptolomey's Star Atlas;
noticing that the positions did not agree Halley thus discovered the phenomenon of stellar proper motion. The ultimate
accolade was his appointment to the post of Astronomer Royal in 1719, at the age of 64, succeeding Flamsteed. Halley
occupied the post for 20 years.
Charles Messier was born on 26 June 1730, in the small French town of Radonviller. Born into a large
family, he received only a simple education, which he completed whilst still at an early age, and at the age of 21, left
to seek work in Paris. He eventually found employment with Nicholas Delisle, who bad established an observatory in the
Hotel du Cluny, where, having been interested in astronomy since his early teens, he found night-time observing very
much to his liking. Eventually Delisle retired, leaving Messier the observatory and equipment for his own use. Messier
devoted his work almost exclusively to the discovery and observation of comets. Between 1760 and 1798 Messier discovered
15 comets.
Although Messier was interested, almost fanatically, in comets, today he is remembered for his catalogue of
nebulae and star clusters. Over the years he spent observing comets, he noticed many nebulous objects and eventually by May
1764 he decided to make a list of as many such objects as he could. By the end of 1764 he had compiled a list of 40
objects, 22 of which he had discovered. He discovered the 41st object in January 1765. The list, with a few
additions, was published in 1769, and the final version, with 103 ojects was printed in 1781. For his services to
astronomy, Messier was elected to many societies and academies all over Europe, including the Royal Society, London, the
Academy of Stockholm, and the Academy of Sciences, Paris.
Joseph Louis Lagrange, the greatest mathematician of the eighteenth century, was born in Turin on January 25, 1736, and died in
Paris on April 10, 1813.
After many years studying and teaching nothing but pure mathematics he worked on the libration of the moon, and an explanation as
to why the same face was always turned to the earth. His solution was interesting as it contained the germ of the idea
of generalized equations of motion, equations which he first formally proved in 1780.
He developed new methods of analytical mechanics; made many theoretical contributions to astronomy, improving our understanding of
lunar motion and the perturbing effects of planets on cometary orbits; found solution to 3-body problem showing there could be
two points (now called Lagrange points) in orbit of Jupiter where minor planets could stay almost indefinitely - the Trojan group
of asteroids were later discovered at these positions.
There are numerous other memoirs on problems in astronomy. The most important of which are:
Friedrich Wilhelm Herschel was born in Hanover, Germany, in 1738. He was the son of a Hanoverian bandsman and he
entered the Hanoverian Foot Guards as an oboe player. In 1755, Herschel visited England, decided that he would like to
stay there, so eventually settled in England, becoming organist at the Octagon Chapel in Bath where he taught musiv and
caught the astonomy bug. Soon he was devoting all his spare time astronomy but not being able to afford a telescope,
Herschel made one, a Newtonian reflector, and in 1774 he began serious astronomical observations.
On Tuesday 13 March 1781, while Herschel was observing the night sky with a 5.7 inch reflector of his own construction,
he found an object in Taurus, near the border with Gemini, which showed a definite disk and which he considered to be
either a nebulous star or perhaps a comet. On observing the object four nights later, he found that it was a Comet.
Continuing his observations he announced his discovery to the Royal Society. The Astronomer Royal at the time was Nevil
Maskelyne who, after observing the object for some time concluded that it was behaving more like a planet than a comet.
Eventually three continental mathematicians, Simon Laplace and Jean Bochart de Sarron in France and Anders Lexell in
Russia, calculated the orbit of the object. They determined that the object had an almost circular orbit at a distance
approximately double that of Saturn from the Sun. Herschel had discovered Uranus. This brought his name to the attention
of other astronomers and eventually George III appointed him King's Astronomer and made him independent of his musical
profession by giving him an annual salary of £250 and an observatory site at Datchet.
Herschel made many important discoveries through the next 30 years. He produced a catalogue of approximately 2500
nebulae and similar objects and made many series of measurements on double and variable stars. After his discovery of
Uranus, his most important work was on the distribution of stars in, and shape of, the galaxy. In 1787 Herschel found
two of the moons of Uranus, Oberon and Titania, and in 1789 he discovered two moons of Saturn, Enceladus and Mimas and
also discovered infra red radiation using a thermometer held at the red end of a spectrum produced by a prism. In 1816,
five year before he died, he was knighted. After Herschel died in 1822, his sister Caroline Lucretia (1750-1848), who
had for several years before been his assistant, carried on his work. His son, Sir John Herschel, also an astronomer
(1792-1871), carried on developing and updating his father's catalogue work.
Giuseppe Piazzi (July 7, 1746 - July 22, 1826) was an Italian Theatine monk, mathematician, and astronomer.
He was born in Ponte in Valtellina, and died in Naples. He established an observatory at Palermo, now the
Osservatorio Astronomico di Palermo "Giuseppe S. Vaiana".
On January 1, 1801, Piazzi discovered a stellar object that moved against the background of stars. At first he
thought it was a fixed star, but once he noticed that it moved, he became convinced it was a planet, or as he called it, "a new star".
In his journal, he wrote: "The light was a little faint, and of the colour of Jupiter, but similar to many others
which generally are reckoned of the eighth magnitude. Therefore I had no doubt of its being any other than a fixed star.
In the evening of the second I repeated my observations, and having found that it did not correspond either in time or
in distance from the zenith with the former observation, I began to entertain some doubts of its accuracy. I conceived
afterwards a great suspicion that it might be a new star. The evening of the third, my suspicion was converted into certainty,
being assured it was not a fixed star. Nevertheless before I made it known, I waited till the evening of the fourth,
when I had the satisfaction to see it had moved at the same rate as on the preceding days."
Piazzi originaly named it "Ceres Ferdinandea", and Carl Friedrich Gauss later determined the Piazzi was right and it was a
small planet. Piazzi named it Ceres after the Roman and Sicilian goddess of grain. It turned out to be the largest of the asteroids.
He also published two new star catalogues. The second catalogue contained over 7600 stars.
In 1923, the 1000th asteroid was named 1000 Piazzi in his honor and more recently the Hubble telescope captured
what appears to be a crater on Ceres. It has been informally named Piazzi. However, under the terms of a 2006
IAU resolution, Ceres can be called a dwarf planet.
Johann Bode was born in Hamburg on 19 January 1747. He became interested in astronomy at an early age.
Throughout his life Bode wrote many books on astronomy, the first being published in 1766 when he was aged only 19.
Between 1774 and 1779 Bode discovered several nebulae of various types. At the end of December 1774, he found two
nebulae in Ursa Major, now known as the galaxies M81 and M82, though at the time of discovery their true nature was
unknown. He discovered more objects in 1775 (including M53) and 1777 (including M92). Bode published a catalogue of some
75 objects during 1777. However, many of the entries were asterisms and non-existent objects obtained from early
catalogues compiled by Hevelius and others. Only about 50 of the entries were in fact nebulae or star clusters, several
of which had positional errors. At around this time, Messier used Bode's catalogue and those of early observers to
compile the most comprehensive and accurate catalogue of nebulae and star clusters yet achieved. The final version of
Messier's catalogue appeared in 1784.
In 1781 it was Bode, who became greatly interested in Herschel's discovery of Uranus discovery, and who
proposed the name finally adopted. Bode is primarily known for his law of relative planetary distances from the Sun.
This law is now of only historical interest, its importance being lost after the discovery of Neptune. In 1786 Bode
became Director of the Berlin Observatory. He held this post for nearly 40 years, retiring in 1825. During 1801 he
published a comprehensive star atlas with the title Uranographia. This atlas proved popular and contained many
new constellations, none of which however were ever officially adopted. The only remnant of Bode's new constellations
today is the Quadrantid Meteors of early January.
Pierre-Simon, marquis de Laplace was a French mathematician and astronomer whose work was pivotal to the development
of mathematical astronomy. He summarized and extended the work of his predecessors in his five volume
"Mécanique Céleste" in which he translated the geometric study of classical mechanics, used by Isaac Newton,
to one based on calculus, opening up a broader range of problems.
Laplace was not yet twenty-four when he entered upon the course of discovery which earned him the
title of "the Newton of France." In a paper read before the Academy of Sciences, on the 10th of February 1773, Laplace
announced his conclusion of the invariability of planetary mean motions. This was the first and most important step in
the establishment of the stability of the solar system. It was followed by a series of investigations, in which Lagrange
and Laplace alternately surpassed and supplemented each other in assigning limits of variation to the several elements
of planetary orbits.
He examined the conditions of stability of the system formed by Saturn's rings, pointed out the necessity for their
rotation, and fixed for it a period (in 10h 33m) virtually identical with that established by the observations of John
Herschel. He also made notable advances in the theory of astronomical refraction, made important mathematical contributions
to differential equations and promoted the solar nebula hypothesis for the origin of the solar system.
Caroline Lucretia Herschel was born on 16 March 1750, sister to the more famous William. Having been brought to
England by her brother she joined him in his astronomical interests. As William performed his systematic sweeps of the
sky he was greatly assisted by Caroline, who amongst other duties was probably most important as a note-taker. Without
this, William would almost certainly never have achieved the huge amount of work he did achieve.
Having her own obsevatory, while free from helping William on 1 August 1786, she discovered a comet which
established her place in the astronomical community. Between 1788 and 1797 she discovered an additional seven comets.
Some of them were independently discovered by others. Importantly Caroline indexed the star catalogue compiled by the
first Astronomer Royal, John Flamsteed, together with a list of omissions. This work was later published. After her
brother's death Caroline returned Hanover where she commenced to prepare a catalogue of nebulae and star clusters
discovered by William. Never published but neverthyeless vey useful to her nephew, John, in his astronomical researches.
Caroline was awarded The Royal Astronomical Society Gold Medal in recognition of her work on compiling
and expanding Flamsteed's star catalogue.
Heinrich Wilhelm Matthias Olbers was born on the 11th of October 1758 at Arbergen, a village near Bremen, where his father was minister.
He studied medicine at Göttingen, taking Kaestner's mathematical course simultaneously. In 1779,
he devised a method of calculating cometary orbits which made an
epoch in the treatment of the subject, and is still extensively used. The greater part of each night
was meantime devoted to astronomy, the upper portion of his house having been fitted out
as an observatory. His special attention was devoted to comets, with that of 1815 bearing his name in
commemoration of its detection by him. He also took a leading part in the discovery of the asteroids, re-identifying
Ceres on the 1st of January 1802, and detected Pallas on the 28th of the folowing March. His hypothesis of their origin
by the disruption of a primitive large planet, though unable to stand the rigours of modern astronomical theory, received
countenance from the finding of Juno by Harding, and of Vesta by himself, exactly in the regions of Cetus and Virgo where
the nodes of such supposed planetary fragments should be situated. Olbers died on the 2nd of March 1840, at the age of eighty-one.
He also posed the famous Olbers' Paradox: "Why is the night sky dark?", and if you think that is a trivial question,
look up the resolution
Friedrich Bessel, an entirely self-taught astronomer, was born on 22 July 1784, in Prussia. His first
significant astronomical achievement came in 1804 when he recalculated the orbit of Halley's Comet and sent his
conclusions to Olbers. As a result of impressing King Frederick William III of Prussia, he was offered control of
construction of a new observatory at Konigsberg where he remained director until his death.
So, Bessel began to make accurate positional measurements of stars for inclusion in a new star catalogue
and on its completion in 1818, Bessel had recorded some 63,000 accurate star positions. His measurements were accurate
enough to reveal the irregularities in the proper motions of Sirius and Procyon, from which he deduced that they must
each have an object in orbit around them. This deduction proved correct and the companion stars were discovered by Clark
in 1862 and Schaeberle in 1892. Bessel is best known today for being the first astronomer to determine a star's distance
from parallax measurements. He used the star 61 Cygni for his measurements because of its relatively large proper motion
and eventualy calculated aparalax of 0.31 arcsec - the moden value is usually considered to be 0.3 arcsec.
He researched the strange motion of Uranus and calculated the masses of Jupiter and Saturn with greater
accuracy than ever before, thus eliminating their influence as the cause of the irregularities of Uranus. Bessel died
some six months before Neptune was discovered.
Born in Straubing, Bavaria, on 6 March 1787. Orphaned at the age of 11, he did an apprenticeship as lens and mirror maker,
after which he became employed in a Munich company making scientific instruments. He learned mathematics and became very
skilled in applied optics. He is especially known for the discovery of the dark absorption lines known as Fraunhofer lines
in the Sun's spectrum, and for making excellent optical glass and achromatic telescope objectives. Fraunhofer worked at
the Optical Institute at Benediktbeuern, a secularised Benedictine monastery devoted to glass making. There he discovered
how to make the world's finest optical glass and invented incredibly precise methods for measuring dispersion. In 1818 he
became the director of the Optical Institute. Due to the fine optical instruments he had developed, Bavaria overtook England
as the centre of the optics industry. Even the likes of Michael Faraday were unable to produce glass that could rival Fraunhofer's.
In 1821 Fraunhofer built the first diffraction grating, comprised of 260 close parallel wires. Well versed in the
mathematical wave theory of light, Fraunhofer used his diffraction grating to actually measure wavelength of specific
colors and dark lines in the solar spectrum. He also built and studied reflection gratings. His career eventually earned him
an honorary doctorate from the University of Erlangen in 1822. In 1824, he was awarded the order of merit, became a noble,
and made an honorary citizen of Munich. Like many glassmakers of his era who were poisoned by heavy metal vapours, Fraunhofer
died young, in 1826 at the age of 39. His most valuable glassmaking recipes are thought to have gone to the grave with him.
Johann Franz Encke was born in Hamburg. In 1811 he went to the University of Gottingen and studied
mathematics and astronomy under Carl Gauss. In 1816 he was appointed assistant at the Seeberg Observatory where he
completed his investigation of the comet of 1680. He then went on to calculate the orbit of comet of 12P/Pons-Brooks
(1812) as being seventy-one years. Subsequent to other cometary calculations he went on to become director of the
Seeberg Observatory in 1822. In 1825 Encke was given the job of guiding the building of a new observatory in Berlin. He
was made director in 1835. While the observatory was being built, he oversaw the making of new star maps and was
involved with the determination and cataloguing the details of other comets and asteroids. he is also known for his work
on transits of Venus, of the earth's distance from the sun, and for his discovery of the division in Saturn's "A" ring
which bears his name.
Friedrich Struve was born on 05 April 1793, in Altona, Germany. To avoid being conscripted into Napoleon's
army, he fled to Russia where he settled for the remainder of his life. In 1815 he became the director of the Dorpat
Observatory which was very well equipped for the period. In 1824, having obtained an equatorially mounted ten-inch
refractor made by Fraunhofer, Struve commenced the study for which he became best known - double stars.He also started a
complete survey of the sky, as far south as -15° declination. At the end of his survey he had catalogued about
120,000 stars including some 2200 doubles which he published the 1827. Struve devised a travelling wire micrometer which
he used to measure the positions of the various components of the double and multiple stars which he discovered. He also
wrote two books on double and multiple stars, the first of which included additional data, increasing the total of
multiple star systems to 3112.
Struve determined the parallax of Vega, arriving at a parallax angle of 0.26 arcsec which value turned out
to be a bit inaccurate, the modern value being accepted as 0.12 arcsec. After holding the post of Director of Dorpat
for 24 years, Tsar Nicholas I of Russia asked Struve to take over the directorship of a new observatory at Pulkovo, to
be built and equipped to Struve's own specifications. He worked there for over 20 years, concentrating on more double
star studies where his son, Otto, assisted with the observations where in 1861 he succeeded his father as director.
William Lassell was born in Bolton. By profession he was originally a brewer but used his fortune to build an observatory
at Starfield near Liverpool. He built his own 24 inch reflector telescope even grinding and polishing the mirror himself.
He also pioneered the use of an equatorial mount. In 1846 Lassell discovered Triton, the largest moon of Neptune just 17
days after Johann Gottfried Galle discovered Neptune itself. In 1848, he independently co-discovered Hyperion, a moon of
Saturn and went on to discover Ariel and Umbriel, two new moons of Uranus, in 1851. In 1855, William Lassell built a 48
inch reflector telescope Malta, claiming that the weather was clearer to observe the night skies. Using this telescope,
Lassell went on to catalogue hundreds of new nebulae. He won the Gold Medal of the Royal Astronomical Society in 1849,
and served as its president for two years starting in 1870. Lassell crater on the Moon, a crater on Mars and a ring of
Neptune are named in his honour.
George Biddell Airy with support from his uncle - and his own hard work, he was able to attend Trinity College,
Cambridge, from which he graduated with the top first class degree. Airy had a long-running feud with Charles Babbage
during his career, over a chair which Airy won at Babbage's expense. Airy was an authoritarian astronomer royal, and
though he was clearly talented, some have suggested his principal gift was making others work - "Airy was not a great
scientist, but he made great science possible." During his tenure, no young astronomers were trained at the observatory,
because he could not tolerate opinions diverging from his own. His personal contributions to the science were relatively
minor - mostly accurate data and corrections of the work of previous scientists - most famously Jean-Baptiste Delambre's
(1749-1822) work on the relative motion of Venus and the Earth. As astronomer royal, he built the Airy Transit Circle,
which defines the exact position of the Greenwich meridian.
Born in Saint-Lô he was educated at the École Polytechnique where at the age of 26 he was appointed as lecturer
in astronomy. Then in 1854 he succeeded Dominique Arago as Director of the Paris Observatory. Le Verrier's
field was in celestial mechanics, one of which stated that every planet should orbit the sun in an ellipse. But
there were errors in the theoretical as opposed to the observed orbit of the planet Uranus. Le Verrier independently
calculated the mass and position of the planet Neptune using these irregularities in Uranus' orbit. In England John
Couch Adams had actually calulated this the year before, but his observational astronomer let him down and Le Verrier,
having had the existence of Neptune observationally confirmed, published first.
Eventually, both men were given the credit of having found the planet jointly. He also worked on
perturbations in the orbit of Mercury, erroneously postulating the existence of another planet closer to the Sun, which he called
Vulcan. This error was eventually resolved by Einstein's general theory of relativity. Le Verrier's work was universally
acclaimed as one of the outstanding scientific achievements of all time. In addition, he organized the French
meteorological service.
With a long and useful career as both a lecturer in and practicer of observational Astronomy Johann Gottfried Galle's
single claim to singular fame was that he was the first person to observe the Planet Neptune, having been asked by Urbain
Le Verrier to check on his calculations. Aside from a mistaken belief that the perturbations in the orbit of Mercury
were caused by another planet (which he called "Vulcan"), his other main interest was in comets of which he compiled
and documented 414 with the help of his son Andreas.
Born in Medelpad and educated at Uppsala University where in 1839 he became a professor of physics. In 1842 he went to
work at Stockholm Observatory. He returned to Uppsala the following year as keeper of its own Astronomical
Oberservatory. He is most famous for his work in spectroscopy, where he eventually analysed the spectrum of the sun
which became the standard authoratitive work for a long time, despite a later proven, minor error in his calculations.
This pioneering use of spectroscopy was recognised by the naming of the ångström, as a unit of length equal
to 1x10-10 metres, though the nanometre, 1x10-9 metres, is now more commonly used. His other
important works were involved in the conduction of heat and he was the first to analyse the spectrum of the aurora
borealis In 1868, he published the results of his extensive research on the solar spectrum with detailed measurements of
more than 1000 spectral lines. The Ångström crater on the Moon was named in his honour.
American, discovered the "Kirkwood gaps" in the orbits of the asteroids between Mars and Jupiter. He also
explained the gaps in Saturn's rings
Pietro Secchi was born on 29 June 1818 in the Italian town of Reggio. At the age of 15
he began studying Astronomy under the Jesuits. Because of religious persecution he was forced to
flee Italy and he settled briefly in the UK but went on to the US where he taught at
Georgetown University, Washington DC. Eventually he was able to return to Italy and
in the new field of spectroscopy Secchi carried out a systematic observational programme,
recording the spectra of approximately 4000 stars between 1864 and 1868.
Before Secchi the only information really known about stars was their position, brightness and colour.
But Secchi noticed that stellar spectra had huge variations and he discovered that stars had different
chemical compositions. In 1867 Secchi proposed that stars could be classified by their spectra.
He originally suggested four spectral classes which has now been expanded to ten. He was also a pioneer
in the use of photography. In 1851, during an eclipse, he took various photographs of the Sun in its
different phases and by 1859 he had photographed the whole of the Moon's visible surface.
William Huggins was born in London on 7 February 1824. He had no scientific education but by 1856 he had built an
8-inch refractor, obtaining the lens from America's Alvan Clark. Three years later Huggins sold the family business
and began concentrating exclusively on astronomy.
During the early nineteenth century ther had been alot of experimentation with prisms and the dispersion of light. This
work led to modern spectroscopy. In 1859 Huggins attended a lecture held by the Pharmaceutical Society, which included a
demonstration of the new spectroscopic techniques. He decided that the new tool of spectroscopy was exactly what he was
looking for. A leading English spectroscopist, one Professor Miller, who was sceptical and was aware that the technical
problems of building spectroscopic equipment sensitive enough for astronomical work posed huge problems. Nevertheless,
Huggins set about the task of building an astronomical spectroscope. Miller encouraged him but was unable to give much
of his own time to the project. Eventually, after much heartache Huggins finally succeeded in pioneering this new branch
of astronomy.
Four years passed until in 1863, Huggins had obtained sufficient data, so he and Miller gave a presentation at the Royal
Society on the spectral lines of several of the brighter stars. A more complete report followed in 1864. He made a major
discovery. Many of his predecessors had seen that many nebulae that could not be resolved into separate stars the
conclusion being that this was due to the equipment. However at the end of August, Huggins recorded the spectrum of a
planetary nebula in Draco. Unexpectedly it had only one bright line thus showing that some nebulae were luminous gas
clouds, and not comprised of stars. He was the first astronomer to be able to distinguish between nebula and galaxies.
After nearly eight years of research Huggins presented a paper on his findings to the British Association. These
results took astronomy a major step forward.
Giovanni Virginio Schiaparelli was born on 14 March 1835 at Savigliano, Italy. He gained a degree from the University of
Turin in 1854 and on leaving university he went to study under Encke at Berlin Observatory and then under Struve at
Pulkovo Observatory in Russia in 1859. Five years later Schiaparelli was appointed Director of Milan Observatory, a
position which he retained until his retirement. The majority of his work was on objects within the Solar System. John
Adams had calculated the orbit of the Leonid meteor showers, showing that it was similar to comets. During the 1860s,
Schiaparelli discovered a connection between Comet 1862 III and the Perseid meteor shower.
In 1877, Mars was at its minimum distance from Earth of 56 million kilometres. From his observations Schiapparelli
accidentally started one of the biggest astronomical hoaxes ever. He convinced himself that some of the features on Mars
were straight lines, with a complicated pattern. In his reports he referred to these lines in Italian as canali,
which was should have been translated into English as channels. The aromatic fertiliser really hit the fan
when the popular press of the time mis-translated this as canals, thus creating the implication that the
structures had been built by intelligent life on the planet.
Several astronomers - who should have known better - carried the idea to extremes. Foremost amongst proponents of
Martian canals was Percival Lowell, who claimed to have observed over 500 of them! Lowell's canals were probably the
result of optical illusions combined with an over-imaginative mind. Many of Lowell's contemporaries reported seeing no
such features. Schiaparelli retired from Milan Observatory in 1900. Up to his death in 1910 he compiled an extensive
survey of early astronomical history, concentrating in particular on Babylonian astronomy.
Sir Joseph Norman Lockyer was born in Rugby on 17 May 1836. In 1857 he directed his attention towards astronomy. With 6.25 inch
refractor by Thomas Cooke of York. For the first few years Lockyer observed the planets, singling out Mars for special
study. When Lockyer heard of the work being done by Kirchhoff and Bunsen he decided to take up spectroscopy, as Huggins
was doing. He conducted his spectroscopic observations quite independently of Huggins. Lockyer concentrated on observing
the Sun, leaving the studying of more remote stellar spectra to others. Lockyer was the first to study the spectra of
sunspots. By 1866 he had amassed sufficient information to to conclude that sunspots appeared dark against the Sun's
disk for two principal reasons:
American, made first photograph of a stellar spectrum (that of Vega). He later photographed spectra of over a hundred
stars and published them in a catalog. He also studied the spectrum of Orion Nebula, which he showed to be a dust cloud
American, discovered the first spectroscopic binary star, Mizar
Dutch, discovered that the proper motions of stars were not random, but stars could be divided into two streams moving in opposite directions, representing the rotation of our galaxy
Edward Emerson Barnard was born in Nashville, Tennessee on 16 December 1851. He received only a mediocre education, and for a
few years made photography his profession. In August 1877, the American Association for the Advancement of Science
(AAAS) held a meeting in Nashville. Barnard had acquired a 5-inch refractor, and he attended the AAAS meeting to seek
advice on how to use it. Having talked to Professor Newcomb who suggested the study of comets, thus was the start of
Barnard's lifelong interest in this subjct.
After searching for around four years, on 12 May 1881 he found his first comet. But despite the fact that it seemed to
disappear, four months later he found the first comet that was to bring his name to prominence, this was Comet 1881 VI.
More followed as Barnard discovered 1882 III, 1884 II and six more comets during the next three years. Every single
commet discovered in 1891 was discovered by Barnard. During 1883, Vanderbilt University awarded Barnard a
fellowship in astronomy. After only a short period there he was put in charge of the University Observatory. As a result
of observing Beta Capricorni flckering he proposed that the star could be a binary. This was confirmed by Dearborn
Observatory, which had a larger telescope. In 1883 he re-discovered the Gegenschein - sunlight scattered by
minute dust particles in the interplanetary medium in the inner Solar System. This had first been reported in 1854. On
completion of his University course, Barnard was appointed assistant astronomer at the Lick Observatory on Mount
Hamilton, California. While at Lick Observatory he made three important discoveries in 1892:
American, classified spectra of many thousands of stars; published catalogs of variable stars (including 300 she discovered)
German, discovered hundreds of asteroids using photography
American, revolutionized spectral observations by inventing and using the spectroheliograph.
He discovered magnetic fields in sunspotsand was the first astronomer to be officially called an astrophysicist.
He founded the Yerkes, Mt. Wilson, and Palomar Observatories
American, discovered the period-luminosity relation for Cepheid variables.
Dutch, studied the astronomical consequences of Einstein's theory of general relativity; deduced that a near-empty universe would expand
German, first to give an exact solution of Einstein's equations of general relativity, giving an understanding of the geometry
of space near a point mass. He also made the first study of black holes
Ejnar Hertzsprung was born on 08 October 1873 He independently discovered the relationship between the absolute
magnitude and the colour of stars. The result was the Hertzsprung-Russell diagram. The H-R diagram, in both its
original and modern forms, has greatly assisted astronomers to understand the evolution of stars.
Educated originally as a chemical engineer, he worked for two years in St. Petersburg until in 1902 he returned to
his native Copenhagen with a great interest in astronomy. After seven years he was appointed as an astrophysical
lecturer at Gottingen. He was one of the first to advance the idea of absolute magnitude. The absolute magnitude of a
star being the magnitude that it would have if it subtended an angle of parallax of 0.1" - 100 milli arc seconds. This
angle resolves to a distance of 10 parsecs. This enables stars of differing luminosities to be directly compared. His
specialisation was stellar photography, particularly of double stars and estimates of stellar magnitude from
photographs. This led to him publish in a semi-popular photographic journal, his ideas about stellar colour and absolute
magnitude. The article went unnoticed for nearly ten years. During 1911 Hertzsprung discovered that the Pole Star was a
Cepheid variable, varying by 0.2 magnitude in a period of about four days. Hertzsprung was appointed professor at Leiden
in Holland in 1935. Upon his retirement, he returned to Denmark.
American, first to measure the radial velocity of the Andromeda galaxy
American, identified Sirius B as the first white dwarf star known
Henry Norris Russell was educated at Princeton University, New Jersey, receiving his doctorate in 1900. He worked for a short
time in England before returning to teach at Princeton. Russell's research led him to the discovery of the
luminosity-colour-spectral class relationships of stars. Russell presented his results at a meeting of the
American Association for the Advancement of Science in December 1913. He published his work in 1914, some
nine years after Hertzsprung.
Russell was one of the first to analyse the composition of the Sun from its spectrum in great detail, during 1929.
He was rather surprised to find that its composition was mostly hydrogen, with helium, oxygen and nitrogen being
the most important trace elements present. He pioneered in the use of atomic physics for the analysis of the stars
and thus played a principal part in laying the foundations of present-day astrophysics. He analyzed the physical
conditions and chemical compositions of stellar atmospheres and evaluated the relative abundance of the elements.
His assertion of the overwhelming abundance of hydrogen was accepted, after prolonged controversy, as one of the
basic facts of cosmology.
Bernhard Voldemar Schmidt was born on 30 March 1879 on a small island called Nargen off the coast of Estonia. In Schmidt's late
teens he enrolled as an engineering student in Gothenburg, Sweden where he specialised in optics. He went to work at
Mittweida. His interest in optics had developed to such a degree that he could support himself financially by making
mirrors and selling them to local amateur astronomers. Beginning in 1900 Schmidt made mirrors up to about 200mm in
diameter. In 1905 he made a 400mm mirror which far surpassed anything then available and as his skill developed he
worked on figuring 300mm, 500mm and 600mm objectives for Leipzig, Potsdam and Hamburg observatories. His reputation
spread rapidly and by 1920 Schmidt had made several mirrors for Hamburg observatory at Bergedorf. Thus in 1926 the
director of the observatory, R Schorr, eventually persuaded Schmidt to join the staff.
From the beginning at Bergedorf, Schmidt was set on overcoming the limitations of conventional telescopes. In 1929,
while on an eclipse expedition with astronomer Walter Baade, he told Baade that he had at last solved the problem of
producing a reflecting telescope that was not only of large aperture but also of wide field of view. Realising the
importance of this new design, Baada urged Schmidt to build one as soon as possible. In late 1929, he began work and
completed his first camera in early 1930 and soon was producing fine photographs. Edwin Hubble of Mount Wilson saw them
he immediately asked Schmidt what was the largest camera that could be built. This turned out to be one of 1.83m
diameter. The two large cameras of Mount Palomar and Siding Springs observatories are of this size. Schmidt continued
work right up to his death.
British, first to confirm Einstein's prediction that light will bend near a star. He also discovered the mass-luminosity relation
for stars and theoretically explained the pulsation of Cepheid variables
American, discovered the size of our galaxy and the direction of its center by studying the distribution of globular clusters.
He also determined the orbits of many eclipsing binary stars
American, first to measure distance to the Andromeda nebula, establishing it to be a separate galaxy; later measured distances to other galaxies and discovered that they recede at a rate proportional to their distance (Hubble's law)
German-born American, discovered the asteroids Hidalgo and Icarus and established two different stellar classes:
the younger, hotter "Population I" and the older, cooler "Population II"
Belgian, advanced idea that the Universe originated as a small, dense "cosmic egg" that exploded and set its expansion into motion
German divided supernovae into Types I and II and optically identified many of the early radio sources
French, invented the coronagraph
Swiss-American, observed Coma cluster of galaxies and determined that most of the cluster must be "dark matter" and proposed
existence of and then observed dwarf galaxies. He proposed existence of supernovas (a term he coined) and that their collapse
might lead to neutron stars. He also anticipated discovery of quasars by proposing that compact blue galaxies might be mistaken
for stars and anticipated that dark matter could be studied by observing galaxies that acted as gravitational lenses
Owner & Webmaster:
Brian Timmins