How every fact on this site was checked
116 facts. Each one is in our own words, each one has a source, and each one was checked against that source on 13 November 2026.
How we check
We read each source and wrote each fact in our own words. Our build stores the text of every source page, and for each fact it checks that the key words and figures, the “checks” in the table, really appear on the source page. If any check fails, the site does not build. Where good sources disagree, we show each version in a “Sources differ” box rather than picking one. Anything that is our own reading, rather than a sourced fact, is labelled Our opinion. The drawings are our own and simplified.
Known disagreements
- Distance to Sagittarius A*. About 26,000 light-years (NASA, 10 questions) or about 27,000 light-years (ESO, 2022).
- The mass of Cygnus X-1. 14.8 Suns (NASA Chandra, 2011), around 20 (ESA, 2024) or 21 (ESO, 2024).
- How heavy a star must be to leave a black hole. Around 20 Suns or more for the star (NASA, types), or more than three solar masses (Britannica).
- The size of the shadow. Roughly twice the black hole’s surface (NASA, anatomy) or about five and a half times the event horizon for M87 (Britannica).
- The most distant black hole. QSO J0313-1806, around 13 billion light-years (NASA’s main black hole page), or one about 13.1 billion light-years away (NASA, 2019).
- The name. Coined by John Wheeler in 1967 (Royal Society) or popularised by him (Britannica).
What we left out
- Some popular figures, such as an exact width of 105,700 light-years, did not appear in the sources we could check, so we give the sources’ own round figures instead.
- One tourist guide we read gives a distance for the Andromeda Galaxy that disagrees with NASA and the Royal Observatory by about a thousand times, so we use NASA’s and the Royal Observatory’s 2.5 million light-years.
- Third-party websites list which Isle of Man sites are “Milky Way” class. We could not confirm that on an official page, so we list the original seven sites without grading them.
- Records and estimates, such as the number of arms or the chance of meeting Andromeda, change as new data arrive. We give them as the named source states them, on the date we checked.
- The galactic odometer is our own arithmetic from the Royal Observatory’s figures, not a quoted fact.
The log
| # | Fact | Source | Checks |
|---|---|---|---|
| 1 | The Milky Way is the galaxy we live in: a huge collection of stars, gas, dust and dark matter, all held together by gravity. | Royal Museums Greenwich: A guide to the Milky Way, our home galaxy (Jake Foster, Royal Observatory) | 3 passed |
| 2 | It is a large barred spiral galaxy. | NASA Imagine the Universe: The Milky Way Galaxy | 1 passed |
| 3 | Every star you can see in the night sky is part of our own Milky Way. | NASA Imagine the Universe: The Milky Way Galaxy | 1 passed |
| 4 | From Earth it looks like a faint, milky band of light arching across the whole sky, which is how it got its name. | NASA Science: Galaxies | 1 passed |
| 5 | That band is the galaxy’s central disc, seen edge on from inside. | NASA Science: Galaxies | 1 passed |
| 6 | Seeing the stars in one band, rather than spread all round the sky, tells astronomers our galaxy is basically flat. | NASA Imagine the Universe: The Milky Way Galaxy | 1 passed |
| 7 | NASA says our galaxy probably contains 100 to 400 billion stars. | NASA Science: Our Milky Way Galaxy: How big is space? | 1 passed |
| 8 | ESA’s guide puts it at about a hundred billion stars. | ESA: Guide to our Galaxy | 1 passed |
| 9 | Britannica says several hundred billion stars, one of which is the Sun. | Encyclopaedia Britannica: Milky Way Galaxy | 1 passed |
| 10 | Counting the stars is very hard because we are inside the galaxy. | NASA Imagine the Universe: The Milky Way Galaxy | 1 passed |
| 11 | The Royal Observatory estimates 100 to 400 billion planets too. | Royal Museums Greenwich: A guide to the Milky Way, our home galaxy (Jake Foster, Royal Observatory) | 1 passed |
| 12 | The Royal Observatory gives its age as roughly 13.6 billion years. | Royal Museums Greenwich: A guide to the Milky Way, our home galaxy (Jake Foster, Royal Observatory) | 1 passed |
| 13 | ESA’s Gaia team says about 13 billion years. | ESA: The billion star surveyor, Gaia Data Release 2 media kit (April 2018, PDF) | 1 passed |
| 14 | Based on the deepest images so far, ours is one of about 2 trillion galaxies in the observable universe. | NASA Science: Our Milky Way Galaxy: How big is space? | 1 passed |
| 15 | A light-year is the distance light travels in a year: about 9.5 trillion kilometres. | NASA Science: Our Milky Way Galaxy: How big is space? | 1 passed |
| 16 | No spacecraft has gone far enough to photograph the Milky Way from outside, so every picture of the whole galaxy is an artist’s impression or a data map. | Royal Museums Greenwich: A guide to the Milky Way, our home galaxy (Jake Foster, Royal Observatory) | 2 passed |
| 17 | A thick layer of dust hides much of the galaxy from ordinary telescopes, so astronomers map it with radio and infrared telescopes. | Encyclopaedia Britannica: Milky Way Galaxy | 2 passed |
| 18 | Its precise shape, true size and mass are still not known. | Encyclopaedia Britannica: Milky Way Galaxy summary | 1 passed |
| 19 | NASA: about 100,000 light-years across. | NASA Science: Our Milky Way Galaxy: How big is space? | 1 passed |
| 20 | NASA’s galaxy page says its disc of stars spans more than 100,000 light-years. | NASA Science: Galaxies | 1 passed |
| 21 | Royal Observatory: approximately 87,000 light-years wide, measured to a set level of brightness (the “isophotal” diameter). | Royal Museums Greenwich: A guide to the Milky Way, our home galaxy (Jake Foster, Royal Observatory) | 1 passed |
| 22 | Britannica’s summary: roughly 150,000 light-years in diameter. | Encyclopaedia Britannica: Milky Way Galaxy summary | 1 passed |
| 23 | The disc is only about 1,000 light-years thick at the spiral arms, rising to around 10,000 light-years at the central bulge. | Royal Museums Greenwich: A guide to the Milky Way, our home galaxy (Jake Foster, Royal Observatory) | 1 passed |
| 24 | ESA describes the star disc as having a radius of about 50,000 light-years but a height of only 1,000 light-years. | ESA: Guide to our Galaxy | 1 passed |
| 25 | Until dark matter is pinned down, the total mass can’t be measured: it is at least several hundred billion, and possibly a trillion, times the Sun’s. | Encyclopaedia Britannica: Milky Way Galaxy, the structure and dynamics | 1 passed |
| 26 | A roughly spherical halo of dark matter about a million light-years wide provides 90% of the galaxy’s total mass. | Royal Museums Greenwich: A guide to the Milky Way, our home galaxy (Jake Foster, Royal Observatory) | 2 passed |
| 27 | Around the disc is a stellar halo of loose stars and globular clusters, thought to be over 300,000 light-years across but holding only 1% of the stars’ mass. | Royal Museums Greenwich: A guide to the Milky Way, our home galaxy (Jake Foster, Royal Observatory) | 2 passed |
| 28 | There are around 160 known globular clusters in the Milky Way: tight balls of hundreds of thousands to millions of stars. | Royal Museums Greenwich: A guide to the Milky Way, our home galaxy (Jake Foster, Royal Observatory) | 2 passed |
| 29 | Astronomers agree it is a spiral with a central bar, with arms of stars and gas coming off each end of the bar. | Royal Museums Greenwich: A guide to the Milky Way, our home galaxy (Jake Foster, Royal Observatory) | 2 passed |
| 30 | The bar is roughly 30,000 light-years across. | Royal Museums Greenwich: A guide to the Milky Way, our home galaxy (Jake Foster, Royal Observatory) | 1 passed |
| 31 | The bar wasn’t proven until 2005, when a team used NASA’s Spitzer Space Telescope to survey stars at the centre in infrared light, which gets through the dust. | Royal Museums Greenwich: A guide to the Milky Way, our home galaxy (Jake Foster, Royal Observatory) | 3 passed |
| 32 | The central bulge holds about ten billion mainly old, red stars and is shaped like a peanut. | ESA: Guide to our Galaxy | 2 passed |
| 33 | The bar joins the bulge on two opposite sides, like a pencil skewering a peanut lengthways. | Royal Museums Greenwich: A guide to the Milky Way, our home galaxy (Jake Foster, Royal Observatory) | 1 passed |
| 34 | In 2008 NASA’s Spitzer team found two major arms, Scutum-Centaurus and Perseus, coming off the ends of the bar; before that four major arms had been assumed. | NASA Science: The Milky Way Galaxy (Spitzer map of the spiral arms) | 3 passed |
| 35 | Later Gaia star maps gave clear evidence for four arms, an ESA scientist says. | ESA: Five fascinating Gaia revelations about the Milky Way | 2 passed |
| 36 | The Royal Observatory names four major arms after the constellations they pass through: Perseus, Scutum-Centaurus, Sagittarius-Carina and Norma/Outer. | Royal Museums Greenwich: A guide to the Milky Way, our home galaxy (Jake Foster, Royal Observatory) | 3 passed |
| 37 | Most of the galaxy’s stars are born in the nebulae of the arms. | Royal Museums Greenwich: A guide to the Milky Way, our home galaxy (Jake Foster, Royal Observatory) | 1 passed |
| 38 | Arms don’t keep the same stars. ESA’s Jos de Bruijne compares them to traffic jams: stars leave at the front while more pile up at the back. | ESA: Five fascinating Gaia revelations about the Milky Way | 3 passed |
| 39 | Jan Oort mapped the first hints of the spiral structure with radio observations in the 1950s. | ESA: Five fascinating Gaia revelations about the Milky Way | 1 passed |
| 40 | The disc is warped, because a ripple is passing through it. | Royal Museums Greenwich: A guide to the Milky Way, our home galaxy (Jake Foster, Royal Observatory) | 1 passed |
| 41 | The Sun is about 26,000 light-years from the centre, roughly halfway between the centre and the outskirts. | ESA: Guide to our Galaxy | 2 passed |
| 42 | Royal Observatory: around 26,000 light-years, about halfway out. | Royal Museums Greenwich: A guide to the Milky Way, our home galaxy (Jake Foster, Royal Observatory) | 1 passed |
| 43 | NASA’s Imagine the Universe: about 25,000 light-years, so we live in the galaxy’s suburbs. | NASA Imagine the Universe: The Milky Way Galaxy | 2 passed |
| 44 | Britannica’s summary: about 27,000 light-years. | Encyclopaedia Britannica: Milky Way Galaxy summary | 1 passed |
| 45 | NASA: Earth sits along one of the spiral arms, about halfway from the centre. | NASA Science: Galaxies | 1 passed |
| 46 | The Sun lies near a small, partial arm called the Orion Arm, or Orion Spur, between the Sagittarius and Perseus arms. | NASA Science: The Milky Way Galaxy (Spitzer map of the spiral arms) | 1 passed |
| 47 | The Orion Arm is an estimated 20,000 light-years long. | Royal Museums Greenwich: A guide to the Milky Way, our home galaxy (Jake Foster, Royal Observatory) | 1 passed |
| 48 | Most of the stars you can see with your eyes alone are in our own arm, and so are the Orion Nebula and the Pleiades. | Royal Museums Greenwich: A guide to the Milky Way, our home galaxy (Jake Foster, Royal Observatory) | 2 passed |
| 49 | The solar system is tilted at about 60 degrees to the galaxy’s disc, which is why the Milky Way crosses our sky at a steep angle to the paths of the planets. | Royal Museums Greenwich: A guide to the Milky Way, our home galaxy (Jake Foster, Royal Observatory) | 2 passed |
| 50 | The solar system travels round the galaxy at about 828,000 km/h (515,000 mph). | Royal Museums Greenwich: A guide to the Milky Way, our home galaxy (Jake Foster, Royal Observatory) | 1 passed |
| 51 | Royal Observatory: one orbit takes about 230 million years, and is called a galactic year. | Royal Museums Greenwich: A guide to the Milky Way, our home galaxy (Jake Foster, Royal Observatory) | 2 passed |
| 52 | ESA: about 230 million years. | ESA: Five fascinating Gaia revelations about the Milky Way | 1 passed |
| 53 | NASA’s galaxy page: about 240 million years. | NASA Science: Galaxies | 1 passed |
| 54 | NASA’s Imagine the Universe: 250 million years. | NASA Imagine the Universe: The Milky Way Galaxy | 1 passed |
| 55 | As we go round, we bob up and down through the disc, one full bob every 60 to 70 million years. | Royal Museums Greenwich: A guide to the Milky Way, our home galaxy (Jake Foster, Royal Observatory) | 2 passed |
| 56 | The Sun lies about 500 light-years from the Radcliffe Wave, a 9,000-light-year ripple of gas clouds found in 2019, and crossed it about 13 million years ago. | ESA: Five fascinating Gaia revelations about the Milky Way | 3 passed |
| 57 | The disc spins at about 220 km per second. | Royal Museums Greenwich: A guide to the Milky Way, our home galaxy (Jake Foster, Royal Observatory) | 1 passed |
| 58 | At the heart of the bulge sits the supermassive black hole Sagittarius A*, with the mass of four million Suns. | Royal Museums Greenwich: A guide to the Milky Way, our home galaxy (Jake Foster, Royal Observatory) | 1 passed |
| 59 | ESO puts the black hole about 27,000 light-years from Earth. | ESO press release eso2208: Astronomers reveal first image of the black hole at the heart of our galaxy (12 May 2022) | 1 passed |
| 60 | NASA puts it 26,000 light-years away, and says there is no danger of Earth being pulled in. | NASA Science: 10 questions you might have about black holes | 1 passed |
| 61 | From that distance it looks about as big in our sky as a doughnut on the Moon. | ESO press release eso2208: Astronomers reveal first image of the black hole at the heart of our galaxy (12 May 2022) | 1 passed |
| 62 | A few hundred light-years from the black hole, a ring of giant gas clouds, the Central Molecular Zone, holds the galaxy’s densest gas. | Royal Museums Greenwich: A guide to the Milky Way, our home galaxy (Jake Foster, Royal Observatory) | 1 passed |
| 63 | The bar pulls gas from the arms and funnels it in towards the centre. | Royal Museums Greenwich: A guide to the Milky Way, our home galaxy (Jake Foster, Royal Observatory) | 1 passed |
| 64 | In ordinary visible light the centre can’t be seen at all: dust between us and it blocks the view, but infrared light gets through. | NASA JPL: A cauldron of stars at the galaxy’s center (Spitzer) | 1 passed |
| 65 | A Spitzer infrared picture shows hundreds of thousands of stars crowded into the centre. | NASA JPL: A cauldron of stars at the galaxy’s center (Spitzer) | 1 passed |
| 66 | Stars have been seen orbiting the black hole as close as a few light-days. | ESA: Guide to our Galaxy | 1 passed |
| 67 | The Milky Way sits in a neighbourhood of more than 50 other galaxies called the Local Group. | NASA Science: Galaxies | 1 passed |
| 68 | ESA’s Gaia team describes the Local Group as the Milky Way, the Andromeda galaxy and about 60 smaller galaxies. | ESA: The billion star surveyor, Gaia Data Release 2 media kit (April 2018, PDF) | 1 passed |
| 69 | The Local Group lies just off the edge of the Virgo cluster and is part of the Laniakea supercluster. | NASA Science: Galaxies | 1 passed |
| 70 | Our nearest large neighbour, the Andromeda Galaxy, is 2.5 million light-years away. | Royal Museums Greenwich: A guide to the Milky Way, our home galaxy (Jake Foster, Royal Observatory) | 1 passed |
| 71 | The Royal Observatory says Andromeda is about 152,000 light-years wide, with more than twice as many stars as the Milky Way. | Royal Museums Greenwich: A guide to the Milky Way, our home galaxy (Jake Foster, Royal Observatory) | 2 passed |
| 72 | NASA says Andromeda is some 220,000 light-years wide. | NASA Science: Our Milky Way Galaxy: How big is space? | 1 passed |
| 73 | Andromeda is getting about 110 km (70 miles) closer to us every second. | Royal Museums Greenwich: A guide to the Milky Way, our home galaxy (Jake Foster, Royal Observatory) | 1 passed |
| 74 | About 60 satellite galaxies are known to orbit the Milky Way, and there may be well over 100. Most are dwarfs, like the Large and Small Magellanic Clouds. | Royal Museums Greenwich: A guide to the Milky Way, our home galaxy (Jake Foster, Royal Observatory) | 3 passed |
| 75 | Britannica gives the Large and Small Magellanic Clouds’ distances as 163,000 and 202,000 light-years. | Encyclopaedia Britannica: Milky Way Galaxy | 1 passed |
| 76 | The nearest companion, the Sagittarius dwarf galaxy, is falling into the Milky Way, captured by its much stronger gravity; its core is about 90,000 light-years away. | Encyclopaedia Britannica: Milky Way Galaxy | 2 passed |
| 77 | Gaia found millions of stars moving in a snail-shell pattern in the disc, probably a ripple from a past brush with the Sagittarius dwarf. | ESA: Five fascinating Gaia revelations about the Milky Way | 2 passed |
| 78 | The Milky Way keeps stripping stars from dwarf galaxies and clusters; Gaia has traced streams of them across the sky. | ESA: Five fascinating Gaia revelations about the Milky Way | 1 passed |
| 79 | From the northern hemisphere, under very dark skies, you may see two other galaxies with your eyes alone: Andromeda and M33. | Royal Museums Greenwich: Astronomy without a telescope, what can I see in the night sky? | 1 passed |
| 80 | In 2012 NASA said Hubble measurements predicted a head-on meeting with Andromeda in about four billion years. | NASA Science: NASA’s Hubble shows Milky Way is destined for head-on collision (31 May 2012) | 2 passed |
| 81 | In that picture the two would merge into a single elliptical galaxy about two billion years after the first encounter. | NASA Science: NASA’s Hubble shows Milky Way is destined for head-on collision (31 May 2012) | 2 passed |
| 82 | Stars are so far apart that they would not hit each other, but the Sun would probably be thrown much farther from the centre. | NASA Science: NASA’s Hubble shows Milky Way is destined for head-on collision (31 May 2012) | 2 passed |
| 83 | Andromeda’s small companion, the Triangulum galaxy (M33), would join in and might later merge with the pair. | NASA Science: NASA’s Hubble shows Milky Way is destined for head-on collision (31 May 2012) | 1 passed |
| 84 | In 2025 a new study using Hubble and Gaia data found only about a 50-50 chance of the two galaxies colliding in the next 10 billion years. | NASA Science: Apocalypse when? Hubble casts doubt on certainty of galactic collision (2 June 2025) | 1 passed |
| 85 | It left only about a 2% chance of a head-on collision in just 4 to 5 billion years. | NASA Science: Apocalypse when? Hubble casts doubt on certainty of galactic collision (2 June 2025) | 1 passed |
| 86 | The team considered 22 variables and ran 100,000 computer simulations reaching 10 billion years ahead. | NASA Science: Apocalypse when? Hubble casts doubt on certainty of galactic collision (2 June 2025) | 2 passed |
| 87 | The Large Magellanic Cloud can change the Milky Way’s path and make a collision less likely. | ESA/Hubble heic2508: Hubble casts doubt on certainty of galactic collision (2 June 2025) | 1 passed |
| 88 | NASA points out that a warming Sun will make Earth uninhabitable in roughly a billion years, so Andromeda is the least of our cosmic worries. | NASA Science: Apocalypse when? Hubble casts doubt on certainty of galactic collision (2 June 2025) | 2 passed |
| 89 | As far back as 1912, astronomers realised Andromeda, then thought to be only a nebula, was heading our way. | NASA Science: Apocalypse when? Hubble casts doubt on certainty of galactic collision (2 June 2025) | 1 passed |
| 90 | The merged galaxy has been unofficially nicknamed Milkomeda. | Royal Museums Greenwich: A guide to the Milky Way, our home galaxy (Jake Foster, Royal Observatory) | 1 passed |
| 91 | With your eyes alone you won’t see the colours in photos: the Milky Way looks like fuzzy, colourless patches of light in a rough strip. | Royal Museums Greenwich: Astronomy without a telescope, what can I see in the night sky? | 2 passed |
| 92 | Let your eyes adjust to the dark for at least 15 minutes, and keep away from bright lights such as your phone screen. | Royal Museums Greenwich: Astronomy without a telescope, what can I see in the night sky? | 1 passed |
| 93 | A red-light torch won’t spoil your night vision, and a planisphere or app shows where to look. | Royal Museums Greenwich: Astronomy without a telescope, what can I see in the night sky? | 2 passed |
| 94 | Full Moonlight counts as light pollution for the fainter sights. | Royal Museums Greenwich: Astronomy without a telescope, what can I see in the night sky? | 1 passed |
| 95 | From the northern hemisphere we mostly look towards the outer arms, away from the dusty centre; from the south the bright core climbs much higher in the sky. | Royal Museums Greenwich: A guide to the Milky Way, our home galaxy (Jake Foster, Royal Observatory) | 2 passed |
| 96 | UK Dark Sky Discovery Sites come in two grades: at “Orion” sites you can see the seven main stars of Orion; at “Milky Way” sites, much darker and found only in rural areas, the Milky Way is visible to the naked eye. | Dark Sky Discovery: Dark Sky Discovery Sites | 3 passed |
| 97 | On 19 October 2012 seven Isle of Man sites became Dark Sky Discovery Sites: Port Soderick Brooghs, Axnfell Plantation, Smeale Nature Reserve, Niarbyl, The Sound, Fort Island and Sulby Reservoir Car Park. | Manx National Heritage: Isle of Man awarded Dark Skies status (19 October 2012) | 3 passed |
| 98 | Manx National Heritage said that put the island on the map with the largest concentration of dark sky sites in Britain. | Manx National Heritage: Isle of Man awarded Dark Skies status (19 October 2012) | 1 passed |
| 99 | NASA astronaut Nicole Stott said she struggled to find the Isle of Man from the International Space Station because it was so dark. | Manx National Heritage: Isle of Man awarded Dark Skies status (19 October 2012) | 1 passed |
| 100 | The Isle of Man now has 26 official dark sky sites. | Visit Isle of Man: Stargazing sites | 1 passed |
| 101 | From them you can see the Milky Way, and the Andromeda Galaxy, with your eyes alone. | Visit Isle of Man: Stargazing sites | 3 passed |
| 102 | In Manx Gaelic the Milky Way is ‘Raad Moaar re Gorree’, the Great Way of Orry, after a tale of the Viking king Orry pointing to it when asked where he had come from. | Visit Isle of Man: Isle of Man Dark Skies guide (PDF) | 3 passed |
| 103 | The island’s dark-skies guide says the Milky Way is best seen there from autumn through to spring. | Visit Isle of Man: Isle of Man Dark Skies guide (PDF) | 1 passed |
| 104 | In winter it stretches from the left of Orion, through Gemini and Cassiopeia, to the north-western horizon; the guide picks Port Soderick, Axnfell, Fort Island and Tholt-y-Will for winter skies. | Visit Isle of Man: Isle of Man Dark Skies guide (PDF) | 2 passed |
| 105 | An ancient Greek story said the Milky Way was milk from the goddess Hera, spilt across the sky as she nursed the baby Heracles. | Royal Museums Greenwich: A guide to the Milky Way, our home galaxy (Jake Foster, Royal Observatory) | 1 passed |
| 106 | Our word ‘galaxy’ comes from the Greek ‘galaxias’, meaning ‘milky’. | Royal Museums Greenwich: A guide to the Milky Way, our home galaxy (Jake Foster, Royal Observatory) | 1 passed |
| 107 | In ancient Greece, Democritus suggested the band might be made of distant stars. | Library of Congress: The Milky Way, one of the many galaxies (Finding Our Place in the Cosmos) | 1 passed |
| 108 | In his 1610 book Sidereus Nuncius, Galileo reported that through a telescope parts of the Milky Way resolved into many stars. | Library of Congress: The Milky Way, one of the many galaxies (Finding Our Place in the Cosmos) | 1 passed |
| 109 | In 1750 the English astronomer Thomas Wright suggested the Milky Way was a flat layer of stars, with our solar system part of it. | Library of Congress: The Milky Way, one of the many galaxies (Finding Our Place in the Cosmos) | 2 passed |
| 110 | In 1755 the philosopher Immanuel Kant called the faint nebulae “island universes”. | Library of Congress: The Milky Way, one of the many galaxies (Finding Our Place in the Cosmos) | 2 passed |
| 111 | In the 1780s William Herschel surveyed the stars in different directions and found them much denser on one side of the sky. | Library of Congress: The Milky Way, one of the many galaxies (Finding Our Place in the Cosmos) | 2 passed |
| 112 | In 1917 Harlow Shapley used globular clusters to show the galaxy is immense, about 100,000 light-years across, with the Sun nearer the edge than the centre. | Encyclopaedia Britannica: Milky Way Galaxy, the structure and dynamics | 3 passed |
| 113 | Only in the 1920s was it confirmed that many nebulous ‘stars’ were whole other galaxies far beyond our own. | Library of Congress: The Milky Way, one of the many galaxies (Finding Our Place in the Cosmos) | 1 passed |
| 114 | The Magellanic Clouds were recognised early in the 20th century as companions of our galaxy. | Encyclopaedia Britannica: Milky Way Galaxy | 1 passed |
| 115 | In April 2018 ESA’s Gaia released a catalogue of nearly 1.7 billion stars, after 22 months of charting the sky. | ESA: Gaia creates richest star map of our Galaxy, and beyond (25 April 2018) | 2 passed |
| 116 | Even so, Gaia’s survey covered almost two billion stars, only about 1% of the galaxy’s total. | ESA: Guide to our Galaxy | 1 passed |