Ten Pangalactic Sunny Challengers Quiz

Answer: Eratosthenes

Eratosthenes was one of the first discoverers to prove, beyond any doubt, that the Earth was a sphere and even calculated its circumference with a precision not to be improved over several hundred years. His method was as simple as it was ingenious: He observed the midday sun in two different cities on nearly the same longitude but different latitude. On one particular day, the sun's light fell entirely vertically in Syene, demonstrated by it reaching the bottom of a deep well. At the same time, however, in Alexandria, further north, a vertically placed stick cast a pronounced shadow, thus proving that the sun was not directly above - as it would have been had the Earth been flat. From the length of the shadow and the distance between the two cities, he was able to calculate the Earth's diameter to 252,000 stadia, which, assuming the Attic stadium as the most likely definition, would evaluate to about 46,000 kilometers, an error of 15%.

You might also have heard Eratosthenes' name in mathematics - the sieve of Eratosthenes, a fast method for finding all primes lower than a given number, was invented by him.

Answer: Tycho Brahe

Brahe's interest in astronomy was awakened at the age of 13, when he observed the solar eclipse of 1560. His most famous observation is the detailed study of the supernova of 1572, the first challenge - and, in fact, outright refutation - to the western belief of an unchanging celestial realm. Brahe also contributed a significant - later refuted - theory of the universe that was widely accepted for over a century, combining between the geocentric model of Ptolemy and the Copernican heliocentric model.

In his model, the Sun did orbit the Earth, but the other planets in turn revolved around the sun, creating an interesting compromise between scientific observation and religious dogma. The injury referred to in the question was of course the famous loss of part of his nose in a duel for which he wore a silver (other sources say gold or copper) prosthesis for the rest of his life.

Answer: Johannes Kepler

Today, Kepler is primarily known for his three laws of planetary motion. Through extensive study of Mars' orbit, he deduced that planetary orbits are ellipses and was able to calculate the orbital periods and speeds of celestial bodies based on their respective distances to the body they orbit. Like many of our challengers, his interests were also quite pangalactic - he also worked on the newly discovered field of logarithms and contributed to the geometry of regular solids, just to name a few.

Answer: Galileo Galilei

I hope the thermometer didn't mislead you from identifying the great Galileo Galilei. He was one of the first astronomers to use a telescope and was instrumental in its improvement. Besides the phases of Venus, he also discovered the four largest moons of Jupiter and the existence of sunspots and he also was the first to observe the rings of Saturn (although he could not recognize them as such).

The observation of Venus' phases was a direct proof that it orbited the Sun, not the Earth, thus finally disproving Ptolemy's model beyond doubt. It however did not directly prove Copernicus' model - Brahe's geoheliocentric model also explained the phases in accordance with the observations.

Answer: Isaac Newton

While not considered an astronomical work by the author, Newton's Principia Mathematica is a fundamental treatise on one of the most important forces in astronomy and all of physics - gravity. Newton's theory of gravity provided a mathematical basis for the empirically derived laws of Kepler while also proving that this fundamental force works the same at any distance, whether it is the easily observed everyday effect of gravity or the complex mechanics of orbiting celestial bodies. Beyond his impact on astronomy and physics, Newton also made a significant impact on calculus and was also a philosopher, theologist and alchemist of note.

Answer: William Herschel

The discovery Herschel changed our perception of the Solar system with was of course his 1781 discovery of Uranus using a telescope he had built himself, using a main mirror with a 15 cm (6 inch) diameter. It was the first such discovery since antiquity - for more than three thousand years, it was believed that the solar system contained just five planets (not counting Earth).

He also remained the only person of the entire 18th century to discover new moons around other planets, two around Saturn and two around Uranus.

He even described Uranus' ring system - a discovery only confirmed in 1977!

Answer: Albert Einstein

I'm talking about Einstein and his (special) theory of relativity - popularly associated with the equation e=mc². Einstein was a mere 26 years old when he published this ground-breaking work that not only established the equivalence of matter and energy - a key concept that led to the understanding how stars generate energy - but also explained how matter and energy interact at the high speeds encountered in astronomy. Einstein's later general theory of relativity (later being, well, relative: he was still in his late 20s and early 30s) overcame an important limit of the earlier theory by making it applicable to objects being accelerated by gravity instead of just those moving at a constant velocity.

Answer: Edwin Hubble

Hubble was the first to prove that what appeared to just be a special form of nebulae were actually complete galaxies outside the Milky Way, ending the belief that the universe and our galaxy were largely one and the same. This observation was however only the first step towards a second, even more important one, namely that the color of light received from distant galaxies was shifted towards red and that the amount of red-shift was consistent with a linear expansion of the universe.

It was only fitting that the Hubble space telescope which was, to a large extent, built to observe the most distant objects we can see at all, would be named after him almost four decades after his death.

Answer: Carl Sagan

Carl Sagan's research interest as an astronomer was always first and foremost the origin of life and its possible existence outside our Solar System. One of his key experiments included the production of amino acids - the most basic building blocks of the proteins forming the base of all life on earth - by bombarding simple, abundant molecules with the intensity and spectrum of radiation prevalent on planets not enjoying the protection of an earthlike atmosphere. Sagan's personal quest however extended outside his own research - he wanted to make science and particularly astronomy popular and put it in people's minds.

His 13-part series "Cosmos: A Personal Voyage" did just that - it was watched by almost a tenth of Earth's population and significantly contributed to the popularization of scientific interest.

Answer: Stephen Hawking

Stephen Hawking has been suffering from a motor neuron disease ever since the age of 21 and was given a remaining life expectancy of two years in 1963. In spite of this debilitating disease (he is practically completely paralyzed and cannot speak) he has gone on to become one of the greatest researchers of our time, finding a way to unify Einstein's general theory of relativity with Planck's quantum mechanics, a discovery that also proved that even black holes - from which seemingly nothing can escape - are not permanent and will evaporate over time by emitting radiation. Hawking also significantly contributed to popularizing science, beginning with his much-acclaimed book "A Brief History of Time".