{"timeline":{"defaultZoomLevel":"0","height":600,"asset":{"media":"\/sites\/default\/files\/discover\/Arabic_astrolabe_publicdomain.jpg","caption":"Arabic Astrolabe from 1280 AD","credit":"Illustration from History of the Astron. Measuring tools 1907 J.A.Repsold"},"date":[{"asset":{"media":"\/sites\/default\/files\/discover\/MulApin-credit-BritishMuseum.png","credit":"British Museum","caption":"MUL.APIN - one of two tablets that document Babylonian astronomy. Thought to be from around 1000 BCE"},"startDate":"-1750","headline":"The First Recorded Observations","text":"

The first documented records of systematic astronomical observations are carried out in Assyria and Babylonia. These astronomers named many of the constellations<\/a> and identified planets visible to the naked eye. Today, these areas are part of Iraq and Syria.<\/p>\n"},{"asset":{"media":"\/sites\/default\/files\/discover\/Ancient_chinese_Dunhuang_star_map_British_Library_PublicDomain.jpg","credit":"British Library","caption":"The Dunhuang map: part of a set of Chinese star maps containing 1,300 stars"},"startDate":"-365","text":"

The first known star<\/a> catalogues are compiled by Chinese astronomers Gan De and Shi Shenfu. They also make observations of sunspots, lunar and solar eclipses, and the planets, particularly Jupiter<\/a>. Their catalogues are used until the 6th century but then lost. <\/p>\n\n

<\/p>\n","headline":"The First Star Maps","tag":"stars"},{"asset":{"media":"\/sites\/default\/files\/discover\/Eratosthenes-credit-publicdomain.jpg?s104707d1623167036","credit":"Bernardo Strozzi (1581\u20131644)","caption":"Eratosthenes teaching in Alexandria"},"headline":"How Big is the Earth?","startDate":"-240","text":"

Greek scholar Eratosthenes is the first known person known to calculate the circumference of the Earth.<\/a> The exact method Eratosthenes' used to calculate Earth's circumference is later lost but is thought to have been based on a solstick experiment<\/a>. In km, Eratosthenes' result is 39,375 km, which is 1.4% less than the real number, 40,076 km.<\/p>\n","tag":"maths"},{"asset":{"media":"\/sites\/default\/files\/discover\/Hipparchus%20astrolabe%20credit%20William%20Cuningham.jpg","credit":"William Cuningham","caption":"A 16th century depiction of astronomer Hipparchus with his astrolabe."},"startDate":"-140","endDate":"-129","headline":"Precession of the Equinoxes","text":"

Greek astronomer Hipparchus maps 850 stars and becomes the first person to observe the precession of the Earth's equinoxes (how the Earth wobbles around its axis of rotation). Though he cannot explain why it occurs. <\/p>\n","tag":"maths"},{"asset":{"media":"\/sites\/default\/files\/discover\/ptolome-the-figure-of-the-world-credit-public-domain.jpg","credit":"Public domain"},"headline":"The Centre of the Universe","startDate":"140","text":"

Astronomers believe that the Earth is at the centre of the Universe<\/a> but are not sure why some planets<\/a> sometimes move \u2018backwards\u2019 across the sky. Claudius Ptolemy \u201csolves\u201d this problem by using a system of circles (or epicycles) to describe how the planets move.<\/p>\n","tag":"orbits"},{"asset":{"media":"\/sites\/default\/files\/discover\/Hypatia.jpg?s40768d1623230108","credit":"Public Domain"},"startDate":"350","endDate":"415","text":"

Hypatia (the first well-known female mathematican, philospher, and astronomer) designs an astrolabe to calculate the positions of stars. Sailors and astronomers use her tables of positions of the stars, Astronomical Canon, for the next 1200 years.<\/p>\n","headline":"The Earliest Female Astronomer","tag":"stars"},{"asset":{"credit":"Unknown author","caption":"Nicolaus Copernicus portrait from Town Hall in Toru\u0144","media":"\/sites\/default\/files\/discover\/491px-Nikolaus_Kopernikus.jpg"},"startDate":"1510","headline":"The Copernican Revolution","text":"

By 1510, Polish astronomer Nicholaus Copernicus has formulated a theory that the Earth and other planets orbit<\/a> the Sun. His work 'On the Revolutions of the Celestial Spheres' is published in the year of his death, 1543. It explains that the apparent backwards motions of other planets is due to the motion of the Earth around the Sun. This is a big change in thinking, and is not widely accepted at first.<\/p>\n","tag":"orbits","endDate":"1543"},{"asset":{"credit":"Anonymous","media":"\/sites\/default\/files\/discover\/562px-Tychonian-credit-publicdomain.png"},"startDate":"1583","headline":"The Tychonic System","text":"

Danish astronomer Tycho Brahe admired Copernicus but does not accept his idea. He develops his own model of the Solar System where the planets orbit<\/a> the Sun, and the Moon orbits the Earth, but the Sun also orbits the Earth.<\/p>\n","tag":"orbits"},{"asset":{"media":"\/sites\/default\/files\/discover\/482px-Circumpolar_AZ81%20polaris%20north%20pole%20star-credit%20lcgs%20russ.jpg","credit":"LCGS Russ","caption":"A very long exposure (7+ hours) of the night sky looking at Polaris, showing star trails. Taken in Northern Arizona."},"headline":"Navigation by the Stars","startDate":"-1100","text":"

Sailors from Phoenicia use the Pole Star (or North Star) for navigation. The Pole Star is located in the constellation of Ursa Minor \u2013 the little bear. Phoenicia was located in what is now Lebanon, Syria and Israel.<\/p>\n","tag":"stars"},{"asset":{"media":"\/sites\/default\/files\/discover\/diagram%20of%20aristarchus%20sun%20centric%20solar%20system%20-%20credit%20public%20domain.jpg?s100774d1623166454","credit":"Public Domain","caption":"Copernicus\u2019s diagram of a Sun centred solar system (anticipated by Aristarchus)."},"headline":"A Sun-centred View","startDate":"-270","text":"

Greek astronomer Aristarchus says that all the planets<\/a>, including the Earth orbit<\/a> the Sun. This idea is later revived in the 16th century by Nicolaus Copernicus. Aristarchus also suspects correctly that stars are unmoving suns far away.<\/p>\n","tag":"orbits"},{"asset":{"media":"\/sites\/default\/files\/kepler_0.jpg","credit":"Credit: Wikimedia (User: ArtMechanic)","caption":"Johannes Kepler"},"headline":"Laws of Planetary Motion","startDate":"1609","text":"

German astronomer Johannes Kepler proposes that the planets move around the Sun in elliptical orbits<\/a>. He uses Tycho Brahe\u2019s data to develop three Laws of Planetary Motion. His model is much more successful at accurately predicting the movements of the planets than Copernicus\u2019.<\/p>\n","tag":"orbits"},{"asset":{"media":"\/sites\/default\/files\/discover\/Galileo_galilei_telescopi1609-credit-sailko.JPG","credit":"Sailko","caption":"Galileo's "cannocchiali" telescopes at the Museo Galileo, Florence"},"headline":"Evidence in Support of Copernicus","startDate":"1610","text":"

Italian astronomer Galileo Galilei observes the sky using a telescope<\/a> he made based on the Dutch telescope design. He discovers that Jupiter has moons<\/a> orbiting around it. This was evidence that objects could orbit something other than Earth and supported Copernicus\u2019 model of the Solar System.<\/p>\n","tag":"orbits"},{"asset":{"credit":"Michel Bakni","media":"\/sites\/default\/files\/discover\/Ibn_Al-Haytham-credit-MichelBakni.jpg"},"startDate":"1011","endDate":"1021","text":"

Ibn al-Haytham (also known as Alhazen) is first scientist in the world to do an experiment using what we now call \u2018the scientific method\u2019. He also paves the way for the modern science of optics<\/a> \u2013 he concludes that we see things when light<\/a> coming from the Sun<\/a> enters our eyes after bouncing off an object and also proves that light travels in a straight line.<\/p>\n","headline":"The Father of Modern Optics","tag":"light"},{"asset":{"media":"\/sites\/default\/files\/astro\/emfig.jpg","caption":"Where infrared light fits into the electromagnetic spectrum","credit":"NSO"},"startDate":"1800","headline":"More to Light than Meets the Eye","text":"

German-British astronomer William Herschel discovers infrared radiation<\/a>. During an investigation of the temperature of different colours of light he observes that the highest temperature was beyond the red light. He hypothesises that this is due to a type of light ray that can\u2019t be seen by human eyes.<\/p>\n","tag":"light"},{"asset":{"media":"\/sites\/default\/files\/discover\/NewtonsTelescopeReplica_wikimedia_user_Solipsist_Andrew_Dunn.jpg","credit":"Wikimedia user: Solipsist (Andrew Dunn)","caption":"A replica of Isaac Newton's second reflecting telescope of 1672"},"startDate":"1668","headline":"The Invention of the Newtonian Telescope","text":"

Isaac Newton grinds his own mirrors and builds the first reflecting telescope<\/a>. The design of his telescope (using a curved primary mirror and a small diagonal mirror) comes to be known as the Newtonian telescope. Almost all of the major telescopes used in astronomy research are reflecting telescopes, including the Liverpool Telescope<\/a>.<\/p>\n","tag":"telescopes"},{"asset":{"credit":"Christiaan Huygens","caption":"Top: Diagram showing how Saturn's appearance to us changes due the changing positions of the Earth (E) and Saturn as they orbit the Sun (G). Bottom: Huygens's observation of Saturn presenting its rings to us at their greatest inclination.","media":"\/sites\/default\/files\/discover\/Huygens%20Saturn-credit-Christian%20Huygens.jpg"},"startDate":"1655","text":"

Dutch astronomer Christiaan Huygens makes the most accurate description of Saturn<\/a> using a refracting telescope<\/a> he has designed. He says Saturn is surrounded by a thin, flat ring. He also discovers Saturn\u2019s largest moon, Titan<\/a>.<\/p>\n","headline":"The Rings of Saturn","tag":"the Solar System"},{"asset":{"media":"\/sites\/default\/files\/activities\/627_Giotto_halley_br.jpg","credit":"ESA","caption":"Comet 1P\/Halley - also known as Halley's Comet"},"startDate":"1680","endDate":"1758","headline":"Halley\u2019s Comet","text":"

English astronomer, Edmund Halley observes a comet<\/a> and correctly predicts when it will return. Comets are large balls of ice, rock and dust but you can think of them as large dirty snowballs that travel through the Solar System. The comet becomes known as Halley\u2019s comet. It is visible from Earth every 75 - 76 years. <\/p>\n","tag":"the Solar System"},{"asset":{"media":"\/sites\/default\/files\/discover\/uranus_neptune_voyager_2_Left_NASAJPL-Caltech_Right_NASA.jpg","credit":"NASA\/JPL-Caltch","caption":"Images of Uranus and Neptune taken by the Voyager 2 spacecraft"},"headline":"Discovery of the Ice Giants","startDate":"1781","endDate":"1845","text":"

Uranus<\/a> becomes the first planet to be discovered using a telescope when William Herschel observes it in 1781. British and French astronomers independently predict the existence of Neptune<\/a>, based on Uranus\u2019 orbit. The discovery is confirmed in 1845. The Solar System now has 8 planets.<\/p>\n","tag":"the Solar System"},{"asset":{"credit":"By Unnkown Author","caption":"The astronomer Clyde Tombaugh, discoverer of Pluto here shown with his homemade 9-inch telescope.","media":"\/sites\/default\/files\/discover\/Clyde_W._Tombaugh_unkown_author_public_domain.jpeg"},"headline":"The Discovery of Pluto","startDate":"1906","endDate":"1930","text":"

American astronomer Percival Lowell predicts a \u2018planet X\u2019 and 24 years later, observations of Pluto<\/a> by astronomer Clyde Tombaugh prove his calculations correct. The Solar System now has 9 planets.<\/p>\n","tag":"the Solar System"},{"asset":{"media":"\/sites\/default\/files\/pluto.jpg","credit":"NASA New Horizons","caption":"Close up of Pluto in 2015"},"headline":"Pluto is Demoted","startDate":"2005","endDate":"2006","text":"

American astronomers discover Eris<\/a> \u2013 a small rocky object beyond Pluto. NASA initially describe it as the Solar System\u2019s 10th planet. The International Astronomical Union create a new classification: \u2018 dwarf planet<\/a>\u2019. Eris and Pluto (and the asteroid Ceres) become dwarf planets. The Solar System has 8 planets again.<\/p>\n","tag":"the Solar System"},{"asset":{"media":"\/sites\/default\/files\/learn\/Ceres.jpg","credit":"NASA\/JPL-Caltech\/UCLA\/MPS\/DLR\/IDA\/Justin Cowart","caption":"Image of Ceres taken by the NASA Dawn spacecraft"},"headline":"Astronomers find the Asteroid Belt","startDate":"1801","endDate":"1850","text":"

Italian astronomer Giuseppe Piazzi makes the first observation of an object in the asteroid belt<\/a>. He names it Ceres (Ceres later is reclassfied as a dwarf planet). German astronomer Henrich Olbers discovers the asteroid, Pallas. In 1802 William Herschel suggests the name \u2018asteroids\u2019 for this new group of objects. By 1850 astronomers are using the term \u2018asteroid belt\u2019.<\/p>\n"},{"asset":{"media":"\/sites\/default\/files\/discover\/Artist-concept-exoplanet-B1257plus12b_credit-NASA_JPL-Caltech.jpg","credit":"NASA\/JPL-Caltech","caption":"Artist's concept of the first exoplanet discovered"},"headline":"Worlds Beyond the Solar System","startDate":"1992","text":"

The first exoplanet<\/a> is discovered. An exoplanet is a planet orbiting a star outside our Solar System. Polish astronomer Aleksander Wolszczan used the Arecibo radio telescope<\/a> in Puerto Rico to find three planets - the first of any kind ever found outside our Solar System - circling a pulsar<\/a> named PSR B1257+12. <\/p>\n"},{"asset":{"media":"\/sites\/default\/files\/discover\/Abd%20al-Rahman%20al-Sufi.jpg","credit":"Abd al-Rahman al-Sufi","caption":"Hare constellation in the astronomy treaty of the Persian scientist Abd al-Rahman al-Sufi"},"startDate":"946","headline":"The First Observations of other Galaxies","text":"

Persian astronomer, Abd al-Rahman al-Sufi is the first astronomer to identify the Large Magellanic Cloud and Andromeda. The first recorded observations of the Large Magellanic Cloud by European astronomers won\u2019t be made until the 16th Century.<\/p>\n","tag":"galaxies"},{"asset":{"media":"\/sites\/default\/files\/discover\/Milky_Way_Night_Sky_Steve_Jurvetson_CC20.jpg","credit":"Steve Jurvetson (Flickr\/Wikipedia)","caption":"The Milky Way in the night sky over Black Rock Desert, Nevada"},"startDate":"1030","headline":"Observations of the Milky Way","text":"

Ibn al-Haytham observes the bright band across the night sky, known as the Milky Way<\/a>. He determines that the Milky Way is outside the Earth\u2019s atmosphere.<\/p>\n","tag":"galaxies"},{"asset":{"credit":"Caroline Herschel","caption":"The shape of our Galaxy as deduced from star counts by William Herschel in 1785. The solar system was assumed near centre.","media":"\/sites\/default\/files\/discover\/Milky%20way%20-%20credit-Caroline%20Herschel.jpg"},"headline":"The Milky Way in detail","startDate":"1610","endDate":"1785","text":"

In 1610, Galileo shows that the Milky Way<\/a> is a made up of many individual stars. In 1785, William Herschel produces the first diagram to try to show the shape of the Milky Way.<\/p>\n","tag":"galaxies"},{"asset":{"caption":"Ultra-violet view of the Andromeda galaxy (M31) from NASA's Galaxy Evolution Explorer","credit":"NASA\/JPL-Caltech","media":"\/sites\/default\/files\/discover\/andromeda_m31_nasa_jpl-caltech.png"},"headline":"There\u2019s stuff outside the Milky Way","startDate":"1924","endDate":"1929","text":"

Hubble shows that the Andromeda nebula is outside the Milky Way<\/a>. This changes scientists view of the Universe. Before now, astronomers had thought that everything was part of the Milky Way galaxy.<\/p>\n","tag":"galaxies"},{"asset":{"media":"\/sites\/default\/files\/astro\/redshiftdemo.jpg","caption":"Comparison of spectra from two galaxies","credit":"NSO"},"headline":"The Universe is Expanding","text":"

Hubble shows that the further away a galaxy is, the more its light has been \u2018 red-shifted<\/a>\u2019. This becomes known as \u2018Hubble\u2019s Law\u2019 and forms part of the evidence for the expansion of the Universe<\/a>.<\/p>\n","startDate":"1929","tag":"galaxies"},{"asset":{"media":"\/sites\/default\/files\/astro\/wmap_s.jpg","credit":"NASA\/WMAP Team","caption":"A map of the Cosmic Microwave Background"},"startDate":"1948","endDate":"1964","headline":"A Signal from the Early Universe","text":"

American scientists, Ralph Alpher and Robert Herman predict the existence of the cosmic microwave background<\/a> (CMB) \u2013 radiation left over from the early Universe. In 1964, American astronomers David Todd Wilkinson and Peter Roll construct a radiometer to detect the CMB. German and American astronomers, Arno Penzias and Robert Woodrow beat them to it and make the first measurement of the CMB using a Dicke radiometer.<\/p>\n","tag":"cosmology"},{"asset":{"media":"\/sites\/default\/files\/astro\/m100_s.jpg","credit":"STSci (HST)","caption":"The spiral galaxy M100"},"headline":"Galaxies Go Dark","startDate":"1978","endDate":"1980","text":"

American astronomers Vera Rubin and Kent Ford provide the first evidence for the existence of dark matter<\/a>. They observe the motions of some galaxies, and calculate that the mass needed to gravitationally<\/a> hold them together is far more than the mass that can be attributed to the stars we see in the galaxy. In other words, there must be a significant amount of unseen mass or dark matter<\/a>. In the case of some spiral galaxies<\/a>, it's been calculated that around 90% of the galaxy must be composed of dark matter.<\/p>\n","tag":"cosmology"},{"asset":{"media":"\/sites\/default\/files\/discover\/black-hole-credit-event-horizon-telescope-collaboration_0.png","credit":"Event Horizon Telescope Collaboration","caption":"The first image of a black hole in the center of the galaxy M87."},"headline":"First image of a black hole","startDate":"2019","endDate":"2019","text":"

The Event Horizon Telescope (an array of radio telescopes around the Earth) published the first image of the shadow of a black hole<\/a>. The black hole is the centre of galaxy Messier 87. The image shows a bright ring formed as light bends in the intense gravity around a black hole that is 6.5 billion times more massive than the Sun. <\/p>\n","tag":"telescopes"},{"asset":{"media":"\/sites\/default\/files\/astro\/hst001.jpg","credit":"NASA\/HST","caption":"Hubble Space Telescope in orbit around Earth"},"headline":"Hubble Space Telescope launched","startDate":"1990","text":"

The largest space telescope, the Hubble Space Telescope<\/a> is launched into low-earth orbit. NASA Chief of Astronomy, Nancy Grace Roman is instrumental in the planning and delivery of the project. The Hubble Space Telescope (HST) is the first telescope to observe from space<\/a>. It is designed to work above the disruptive effects of the atmosphere and orbits 600 km (372 miles) above the Earth's surface.<\/p>\n","tag":"telescopes"},{"asset":{"credit":"Ferdinand Schmutzer","media":"\/sites\/default\/files\/discover\/Einstein_1921_by_F_Schmutzer_public_domain.jpg","caption":"Albert Einstein in 1921"},"startDate":"1905","headline":"Space-time","text":"

German physicist, Albert Einstein shows that space and time are linked \u2013 a theory known as special relativity<\/a>. It explains that as an object approaches the speed of light, its mass becomes infinite and it is unable to go any faster than light travels. It also shows that shows that energy and mass are interchangeable and includes the famous equation:<\/p>\n\n

\\[ E=mc^2 \\]<\/p>\n","tag":"cosmology"},{"asset":{"media":"\/sites\/default\/files\/discover\/Spacetime_curvature_NASA.png","credit":"NASA","caption":"Gravity can be thought of as the movements of particles through curved space-time."},"startDate":"1915","headline":"New Understanding of Gravity","text":"

Einstein publishes his theory of general relativity<\/a> - that because objects in space are so massive, they actually cause space (and time) to curve around them. This theory implies the existence of black holes<\/a> and predicts the existence of gravitational waves<\/a>. <\/p>\n","tag":"gravity"},{"asset":{"media":"\/sites\/default\/files\/astro\/eclipse.jpg","caption":"Total Solar Eclipse from France, 1999","credit":"Luc Viatour"},"startDate":"1919","headline":"The Eddington Experiment","text":"

Arthur Eddington observes a solar eclipse<\/a> to test Einstein\u2019s theory of General Relativity<\/a>. Eddington measures how much starlight has been deflected by the gravity of the Sun<\/a>. His findings support Einstein\u2019s theory.<\/p>\n\n

He later wrote this short poem about the discovery:<\/p>\n\n

Oh leave the Wise our measures to collate
\nOne thing at least is certain, LIGHT has WEIGHT,
\nOne thing is certain, and the rest debate\u2014
\nLight-rays, when near the Sun, DO NOT GO STRAIGHT.<\/em><\/p>\n","tag":"gravity"},{"asset":{"media":"\/sites\/default\/files\/ns_gw_art_0.jpg","credit":"J Hurt\/JPL-Caltech","caption":"Gravitational waves caused by two orbiting neutron stars"},"startDate":"2015","headline":"Einstein was Right","text":"

The LIGO<\/a> (Laser Interferometer Gravitational-Wave Observatory) team announce the first direct detection of gravitational waves<\/a>. The waves were produced by the merger of two black holes<\/a>, 1.3 billion light-years away.<\/p>\n","tag":"gravity"},{"asset":{"media":"\/sites\/default\/files\/GodfreyKneller-IsaacNewton-1689_0.jpg","caption":"Isaac Newton","credit":"G Kneller"},"startDate":"1687","headline":"Newton's Laws of Gravity","text":"

Isaac Newton publishes work that becomes known as the Law of Universal Gravitation. This explains how the force of gravity<\/a> acts between every particle and object in the Universe. Newton\u2019s work is the first to unify theories of gravity and astronomy and establishes gravity as a fundamental force throughout the Universe<\/a>. <\/p>\n","tag":"gravity"},{"asset":{"media":"\/sites\/default\/files\/astro\/earth_gravity.png","caption":"The pull of gravity around the Earth","credit":"Wikimedia user Sjlegg"},"startDate":"600","endDate":"700","headline":"First Ideas about Gravity","text":"

Gravity<\/a> is first identified as an attractive force by Indian mathematician and astronomer, Brahmagupta. He writes that \"bodies fall towards the earth as it is in the nature of the earth to attract bodies, just as it is in the nature of water to flow\". Brahmagupta creates methods for calculating the positions of heavenly bodies over time including rising and setting, conjunctions, and the calculation of solar and lunar eclipses. He also writes a book containing the first rules for doing arithmetic with zero and negative numbers.<\/p>\n","tag":"gravity"},{"asset":{"credit":"Rijksmuseum","caption":"Portrait of Galileo Galilei.","media":"\/sites\/default\/files\/discover\/YR0150156_Portrait-of-Galileo-Galilei.jpg"},"startDate":"1589","endDate":"1592","headline":"Galileo's Experiment","text":"

Galileo Galilei\u2019s investigations lead him to realise that objects fall with constant acceleration and that, if you remove air resistance and buoyancy, all objects fall at the same rate. <\/p>\n","tag":"gravity"},{"asset":{"media":"\/sites\/default\/files\/discover\/Karl_schwarzschild_public_domain.jpg","caption":"Karl Schwarzschild","credit":"Wikipedia - public domain"},"startDate":"1915","headline":"How Big is a Blackhole?","text":"

Karl Schwarzschild finds the first exact answer to Albert Einstein\u2019s equations of general relativity. His work includes calculating the radius of the event horizon of a black hole<\/a> \u2013 now known as the Schwarzschild radius.<\/p>\n","tag":"stellar evolution"},{"asset":{"media":"\/sites\/default\/files\/discover\/Istambul_observatory_in_1577-credit-publicdomain_0.jpg","credit":"Anonymous Ottoman artist.","caption":"An observatory in Istanbul"},"startDate":"800","endDate":"1200","headline":"The Golden Age of Islamic Astronomy","text":"

The Islamic Golden Age lasts from around 800 AD to 1300 AD. During this time, Islamic scholars make advances in several areas of science and maths, including astronomy<\/a>. Their work builds on and improves Ptolemy's models, which has been recently translated into Arabic. <\/p>\n\n

They build observational sextants (a sceintific instrument that can workout the angle between the horizon and a celestial body) to study the angles of stars, movements of stars and understanding of planets\u2019 orbits. The first major observatories are also set up during this time. Some of the key achievements are measuring the thickness of the Earth's atmosphere<\/a>, developing trigonometry and algebra that can be used on spheres, and cataloguing and naming a large number of stars (many names that are still used today like Aldebaran, Betelgeuse, Rigel). The most influential Islamic astronomers are Abd al-Rahman al-Sufi, Abu Rayhan al-Biruni, and Ibn al-Haytham (known in Europe as Alhazen).<\/p>\n"},{"asset":{"credit":"Stellarium, Supernovae Plug-in by Alexander Wolf, screenshot captured by User:JWNoctis","caption":"Simulated supernova SN 1054 at the position of Crab Nebula, as would have been seen from China.","media":"\/sites\/default\/files\/discover\/SN_1054_4th_Jul_1054-credit-stellarium.png"},"startDate":"1054","text":"

Astronomers in China, Japan and the Islamic world observe a bright \u2018new star\u2019. It stays bright enough to be seen until 1056.<\/p>\n\n

In 1731 the Crab Nebula is first identified. In the early 20th century, astronomers realise that the 'new star' of 1054 could have been caused by a massive explosion connected to the Crab Nebula. In 1942 the Crab Nebula is confirmed to have been created by the supernova<\/a> that was first observed in 1054.<\/p>\n","headline":"A \u2018New star\u2019","tag":"stars","endDate":"1056"},{"asset":{"media":"\/sites\/default\/files\/learn\/sun_jpl.jpg","caption":"Helium was found in the Sun before it was found on Earth","credit":"JPL - NASA\/SDO\/AIA"},"text":"

British and French astronomers, Norman Lockyer and Pierre Janssen both observe a feature in a spectra<\/a> from the Sun that Lockyer realises is a new element. He names it helium. Helium isn\u2019t found on Earth until 1895.<\/p>\n","startDate":"1868","endDate":"1895","headline":"Helium: A New Element","tag":"stars"},{"asset":{"media":"\/sites\/default\/files\/learn\/469px-Arthur_Stanley_Eddington.jpg","caption":"Sir Arthur Eddington","credit":"United States\u00a0Library of Congress'\u00a0 Prints and Photographs division"},"headline":"Why do stars shine?","startDate":"1920","text":"

Arthur Eddington is the first person to propose that stars are powered by the nuclear fusion<\/a> of hydrogen into helium. We now understand that fusion happens when two lightweight atoms are forced together to form a heavier atom, and a lot of energy is produced as a result. From the 1940s onwards, scientists will try and recreate the incredibly high temperatures and pressures found at the centre of star to produce fusion reactions in laboratories on Earth, but without success.<\/p>\n","tag":"stars"},{"asset":{"media":"\/sites\/default\/files\/astro\/Cecilia_P-G.png","caption":"Cecilia Payne Gaposchkin","credit":"Royal Astronomical Society, care of the Smithsonian Institution"},"startDate":"1925","headline":"What is the Sun Made of?","text":"

Cecilia Helena Payne-Gaposchkin shows that there is far more hydrogen and helium in the Sun<\/a> than there is in the Earth and so discovers that hydrogen is the main element in stars and, therefore, must also be the most abundant element in the Universe<\/a>. Other scientists reject her ideas because they believe that the Earth and Sun are made up of the same amounts of all the elements. Cecilia is later proved to be correct but another scientist claims credit for her discovery.<\/p>\n","tag":"stars"},{"asset":{"media":"\/sites\/default\/files\/astro\/hr-diagram-credit-nso.png","credit":"NSO","caption":"The Hertzsprung-Russell diagram"},"headline":"The Hertzsprung-Russell Diagram","startDate":"1913","text":"

The Hertzsprung-Russell Diagram<\/a> is developed independently by Danish and American astronomers. It is a graph that plots the temperature of a star against its absolute magnitude<\/a> or luminosity. Most stars, including the Sun, can be found in the main sequence of stars - a prominent band running from the top-left to the bottom-right of the diagram. Stars move into different areas of the chart as they run out of nuclear fuel. The diagram is a massive step forward in astronomers' understanding of how stars evolve.<\/p>\n","tag":"stellar evolution"},{"asset":{"media":"\/sites\/default\/files\/careers\/subrahmanyan-chandrasekhar-credit-startchild-project-nasa.gif","credit":"Starchild Project NASA","caption":"Subrahmanyan Chandrasekhar"},"headline":"The Chandrasekhar limit","startDate":"1931","text":"

Indian-American astrophysicist, Subrahmanyan Chandrasekhar uses special relativity to calculate the maximum mass a white dwarf star<\/a> can contain before it collapses. The Chandrasekhar Limit is now accepted to be approximately 1.4 times the mass of the Sun<\/a>.<\/p>\n","tag":"stellar evolution"},{"asset":{"media":"\/sites\/default\/files\/learn\/BellBurnell.jpeg","credit":"Wikimedia (User: Anrie)","caption":"Jocelyn Bell-Burnell"},"text":"

Jocelyn Bell-Burnell<\/a> discovers a steady radio signal<\/a> from space. This is soon shown not to be a signal from intelligent life elsewhere, but the first detection of a pulsar<\/a>. Pulsars are rapidly rotating neutron stars<\/a>. Up until now, neutron stars had just been theoretical.<\/p>\n","headline":"Little Green Men?","startDate":"1967","tag":"stellar evolution"},{"asset":{"media":"\/sites\/default\/files\/discover\/Hans-Lipperhey-by_Pierre_Borel_public-domain.jpg","credit":"Pierre Borel","caption":"Portrait of Hans Lipperhey"},"startDate":"1608","text":"

German-Dutch spectacle maker, Hans Lipperhey (sometimes spelt Lippershey) is the first person to file a patent for a refracting telescope<\/a>. He applies to the States General of the Netherlands on 2 October 1608 for a patent for his instrument \"for seeing things far away as if they were nearby\". He did not receive a patent (because other lens makers seemed to be making similar devices) but the government paid him for his design. The first Dutch telescopes consist of a convex and concave lens<\/a>.<\/p>\n","headline":"The First Telescopes","tag":"telescopes"},{"asset":{"media":"\/sites\/default\/files\/discover\/The_Antikythera_Mechanism_By_Tilemahos_Efthimiadis_Uploaded%20by%20Marcus%20Cyron_CC20.jpg","caption":"A Fragment of the The Antikythera mechanism","credit":"Tilemahos Efthimiadis, Uploaded to Wikimedia by Marcus Cyron"},"headline":"The Antikythera mechanism","text":"

Ancient Greeks build an astronomical calculator - a bit like an ancient mechanical computer. It uses bronze gears (similarly to an Orrery<\/a>) to make astronomical predictions. It is about the size of a table-top clock and can be used to track the paths of the Sun, Moon and planets. <\/p>\n\n

In 1901, the remains of the mechanism will be found by archaeologists investigating an ancient ship wreck.<\/p>\n","startDate":"-100"}],"language":"en","headline":"Timeline of Astronomy","text":"

Our ideas about the Solar System<\/a> and beyond have developed over time. Humans have looked to the skies and observed the apparent movement and changes in the Sun<\/a>, Moon<\/a> and stars<\/a> for thousands of years. People with knowledge of star positions, solar eclipses<\/a>, and lunar cycles<\/a> could create star maps, calendars and measure time. This was useful for farming and navigation. <\/div>\n","era":[{"headline":"Islamic Golden Age","startDate":"800","endDate":"1300","text":""},{"startDate":"-499","endDate":"27","headline":"Ancient Greece","text":""},{"headline":"European Scientific Revolution","startDate":"1543","endDate":"1800","text":""},{"startDate":"1801","headline":"Modern Era","text":"","endDate":"2100"},{"startDate":"1957","endDate":"2100","headline":"The Space Age","text":""}]}}

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