Built on All That We Have Done Quiz

Answer: Anaximander

Anaximander lived in the city of Miletus (whose ruins are located in modern-day Turkey) from around 610 BCE to around 546 BCE. He was one of the first Greek-culture philosophers to write down his work, rather than just transmitting it orally to his pupils, but only a fragment has survived. Greek philosophers studied a number of areas which we would now consider independent fields of thought, especially mathematics and the physical sciences. Anaximander was particularly interested in the origins of the universe, and attempted to construct an explanation of the motion of celestial objects that was based on physical, rather than mythological, principles.

Anaximander's idea that the earth was freely floating in space is identified by many as the key to making the science of astronomy possible, as it allowed one to contemplate other bodies as passing under, as well as over, the earth. His model also allowed for various objects to be at different distances, rather than all being at the same distance on a celestial sphere.

Answer: Eratosthenes

While Anaximander had suggested that the earth's axis had a tilt, it was Eratosthenes of Cyrene (c. 276 BCE - c. 195 BCE) who is credited with being the first to make an accurate measurement of that tilt. This was only one of many subjects on which he wrote scholarly treatises, but most of his work was lost when the Great Library of Alexandria (where he worked as chief librarian) was destroyed. Eratosthenes did not actually make experimental observations himself; rather, he analysed the multitude of work that was available at the library.

As well as determining the earth's axial tilt, Eratosthenes compiled an accurate star catalogue, developed a calendar that included leap years, determined the circumference of the earth, and created the first known global projection (as opposed to flat-earth depiction) of the world, including an indication of parallels and meridians. You may recall from school days his method of producing a list of all prime numbers, called the Sieve of Eratosthenes - clever, but tedious when done manually for numbers over around 100.

Answer: Al-Battani

Abu 'Abd Allah Muhammad ibn Jabir ibn Sinan al-Raqqi al-Harrani as-Sabi' al-Battani is more usually referred to by the simpler Al-Battani, or the Latinized Albategnius. Born around 858 in the town of Harran (in southeastern Turkey), he worked from around 877 until around 918 in the Syrian city of Raqqah. Al-Battani is often called the "Ptolemy of the Arabs" - a somewhat ethnocentric designation for a man of significant accomplishments. His major work was 'Kitab az-Zij', which was translated into Latin as 'De Motu Stellarum' ('On the Motion of Stars') by Plato of Tivoli in 1116. His figures were more accurate than the earlier Ptolemaic data, and his work was often cited by the astronomers who will follow in this quiz.

Al-Battani also determined the length of the solar year, to within two and a half minutes of the currently-accepted value, and explained how an annular solar eclipse can occur. High school students have him to thank for developing the trigonometric concepts of the tangent and secant.

Answer: Al-Sufi

'Abd al-Rahman al-Sufi (903-986) was commonly called Azophi Arabus by European astronomers. Al-Sufi published 'Kitab al-Kawatib al-Thabit al-Musawwar' ('Book of Fixed Stars') in 964. Although he was Persian, he wrote in the accepted scholarly language of Arabic.

In it, he compared Greek and Arabic constellations and produced a star chart of the forty-eight Ptolemaic constellations (including both the main stars that produce the image for the constellation, and the nearby stars within it). These charts included not only names and longitudinal and latitudinal coordinates for each star, but also the magnitude (apparent brightness) of each star.

This significant work did not get translated into English until 2010! Fortunately, images transcend the barriers of language.

Answer: Tycho Brahe

Tycho Brahe (1546-1601) is known for his painstaking compilation of amazingly accurate astronomical data. (He was apparently considered something of a tyrant by those whose work he directed, but that's another story.) The last major astronomer to work without telescopes, be developed a model of the solar system (called the Tychonic model) in which the sun orbited the earth, while the other planets orbited the sun. In mathematical analysis of observations, this model was equivalent to the Copernican model. In 1573 his 'De Nova Stella' ('On the New Star') established the existence of what is now called a supernova, and refuted Aristotle's belief that the universe was essentially static in nature.

King Frederick II gave Tycho an estate on the island of Ven, and the money needed to build Uraniborg, which became an internationally-acclaimed research centre, attracting astronomers from all over Europe. In 1597, following a dispute with the new Danish king, he went to Prague, where he became the official astronomer for the Holy Roman Empire. Johannes Kepler, who worked there as his assistant, later used Tycho's data in developing his Three Laws of Planetary Motion (published between 1609 and 1619).

Answer: Galileo Galilei

Galileo di Vincenzo Bonaiuti de' Galilei (1564 - 1642) was born in the city of Pisa, in the Duchy of Florence, and originally planned a career in medicine, before becoming fascinated by a desire to explain physical phenomena. He is known for many aspects of his scientific work, and many of his experiments are routinely repeated by high school students. But he may be best known for his support of a heliocentric model of the solar system, in direct defiance of Church teachings at the time. (He was excommunicated in 1633 for passages in his 'Dialogue Concerning the Two Chief World Systems' that could be interpreted as supporting the model that had been banned in 1616; the error of this action was formally acknowledged in 1992.)

Galileo was the first astronomer to make extensive use of telescopes in his work (as well as forming a lucrative sideline in selling them to others). His observations of the moon showed that its surface was composed of mountains and craters, as opposed to the long-accepted belief that it was a perfect sphere. He discovered four moons of Jupiter, now referred to as the Galilean moons; this discovery was revolutionary, s it contradicted the Aristotelian model that had all celestial objects orbiting the earth. His observation of the phases of Venus provided further support for a heliocentric solar system.

Answer: William Herschel

And that planet was Uranus, which William Herschel (1738-1822) first noted on 13 March 1781 as part of his project to construct a catalogue of nebulae, using a telescope that he constructed himself in 1774. While this discovery gained him instant fame, including an appointment as Court Astronomer, and access to funds for improving his research tools, it was far from his only contribution to astronomy.

As well as discovering a number of new planetary moons and determining the axial tilt of Mars (along with the observation that its polar ice caps changed size seasonally), he determined that light from the sun included frequencies outside the visible spectrum - specifically identifying the presence of infrared radiation in 1800.

Answer: Edmond Halley

Edmond Halley (1656-1742) was appointed as the second British Astronomer Royal in 1720, based on a number of significant achievements. In 1676-7 he used an observatory he had constructed on Saint Helena to gather data from which he would later produce a catalogue of the southern celestial sphere. He recorded a transit of Mercury, and realised that measurements on a transit of Venus would allow measurement of the distances between that planet, the earth and the sun. Unfortunately, the next transit was not due until 1761, at which time many astronomers, using vantage points around the world, made observations.

The Italian astronomer Cassini told Halley of his theory that comets were orbiting objects, and in 1682 Halley made observations on the motion of a comet (later to be known as Halley's comet). Using the work of Isaac Newton (whose 'Philosophiæ Naturalis Principia Mathematica' Halley was instrumental in getting published), Halley determined the orbit of this comet, predicting in his 1705 'Synopsis of the Astronomy of Comets' that it would appear again in 1758, which it duly did, and identifying it as the same comet that had been previously seen in 1531 and 1607.

Answer: Percival Lowell

Percival Lowell (1855-1916) was a firm believer that there were canals on Mars, possibly evidence of extra-terrestrial life. This dominated his written work between 1893 and 1908, and contributed to the popularity of this concept among members of the public. Astronomers, however, were less inclined to agree; in 1909 observations made at the Mount Palomar Observatory showed the lines to be geologic structures, not man-made, and the actual landings on Mars have definitively shown him to have been wrong. Nevertheless, he did stimulate public interest in astronomy!

Possibly Lowell's most significant contribution to the development of astronomy lay in his work, starting in 1909, to try and locate a hypothetical planet located further from the sun than Neptune. This culminated in observations made by Clyde Tombaugh, using the Lowell Observatory telescope, identifying Pluto as the body in question. Between 1930 and 2006, Pluto was considered to be the ninth planet of our solar system; a new and more rigorous definition of a planet, made necessary by the discovery of an ever-increasing number of asteroids, led to the reclassification of Pluto as a dwarf planet.

Answer: Edwin Hubble

The American astronomer Edwin Powell Hubble (1889 - 1953) was one of the pioneers in the field of extragalactic astronomy - the acceptance that there was more to the universe than our own galaxy. His work showed that objects previously classified as nebulae (clouds of dust and gas) were in fact galaxies. These objects had previously been shown to be moving away from the earth; Hubble developed a technique to correlate distance and recessional velocity, supporting a theory previously proposed by Georges Lemaître, and now commonly known as Hubble's Law, stating that the further away an object is, the faster it is receding. While this was seen by many as implying that the universe is expanding, Hubble himself insisted that there must be some other explanation for the phenomenon.

The Hubble Space Telescope, named in his honour, was launched in 1990. It operates in a low earth orbit (a bit further out than a geosynchronous orbit which would keep it in place over one point on the earth's surface), with an orbital pattern that takes about eight weeks. When initially launched, it was found to have a faulty mirror, because one part had been placed 1.3 mm (0.051 in) away from the correct spot. fortunately, it was possible to make the necessary corrections during the telescope's first scheduled maintenance, in 1993.