How every fact on this site was checked
151 facts. Each one is in our own words, each one has a source, and each one was checked against that source on 10 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; the chirp drawing is an illustration, not real data.
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
- A physics society page gives the year Wheeler first used the name “black hole” as 1968, but it would not load for us to check, so we use the Royal Society’s 1967 and Britannica’s “popularised” instead.
- Britannica’s pages on Hawking radiation and Stephen Hawking would not load for us, so Hawking facts come from NASA and Britannica’s main black hole article only.
- Records such as the heaviest, lightest, nearest and most distant black holes change as new discoveries are made. We give them as the named source states them, on the date we checked.
- The squash-it calculator is our own arithmetic from Britannica’s figures, not a quoted fact.
The log
| # | Fact | Source | Checks |
|---|---|---|---|
| 1 | A black hole is a place where gravity is so strong that nothing, not even light, can escape from it. | NASA Space Place: What is a black hole? | 2 passed |
| 2 | Black holes aren’t really holes. They are huge amounts of matter packed into very small spaces. | NASA Science: Black holes (overview and essential facts) | 2 passed |
| 3 | The edge of a black hole is the event horizon. It isn’t a solid surface like Earth’s: it is a boundary that contains all of the black hole’s matter. | NASA Science: Black holes (overview and essential facts) | 2 passed |
| 4 | Inside the event horizon, the speed you would need to escape is greater than the speed of light, and nothing can go faster than light. | NASA Science: Black hole anatomy | 2 passed |
| 5 | No light of any kind, not even X-rays, can get out from inside the event horizon. | NASA Science: 10 questions you might have about black holes | 1 passed |
| 6 | So black holes neither give out nor reflect light, and nothing that happens inside them can reach anyone outside. | NASA Science: Black hole anatomy | 1 passed |
| 7 | Most of the light we see comes from the accretion disk: gas that settles into a hot, bright, fast-spinning disk and slowly works its way in until it falls through the event horizon. | NASA Science: Black hole anatomy | 2 passed |
| 8 | Gas pulled towards a black hole is heated to millions of degrees, so it glows in X-rays. | NASA Science: 10 questions you might have about black holes | 2 passed |
| 9 | NASA says the dark zone called the event horizon shadow is roughly twice as big as the black hole’s actual surface. | NASA Science: Black hole anatomy | 1 passed |
| 10 | Britannica says the shadow of the black hole in M87 is about five and a half times larger than its event horizon. | Encyclopaedia Britannica: Black hole | 1 passed |
| 11 | Thin rings of light at the edge of the shadow are distorted images of the disk, made by light that has gone round the black hole several times before escaping. | NASA Science: Black hole anatomy | 1 passed |
| 12 | One side of the disk usually looks brighter: gas spinning towards us looks brighter and bluer, and gas spinning away looks dimmer and redder. | NASA Science: Black hole anatomy | 2 passed |
| 13 | Above the disk is the corona, a thin, turbulent cloud at about a billion degrees that gives out high-energy X-rays. | NASA Science: Black hole anatomy | 1 passed |
| 14 | A little of the material heading in can be redirected into a pair of jets that blast away in opposite directions at close to the speed of light. | NASA Science: Black hole anatomy | 2 passed |
| 15 | The jets from supermassive black holes can be hundreds of thousands of light-years long. | NASA Science: Black hole anatomy | 1 passed |
| 16 | Einstein’s general relativity predicts that the very centre holds a singularity, a point where matter is crushed to infinite density. | NASA Science: Black hole anatomy | 1 passed |
| 17 | Nobody yet knows whether the singularity is a real physical thing or only a feature of the mathematics. It may mark the point where relativity stops working. | NASA Science: Black hole anatomy | 2 passed |
| 18 | The radius of the event horizon is called the Schwarzschild radius, after the German astronomer Karl Schwarzschild. | Encyclopaedia Britannica: Black hole | 1 passed |
| 19 | The Schwarzschild radius is Rg = 2GM/c², where M is the mass, G is the gravitational constant and c is the speed of light. | Encyclopaedia Britannica: Schwarzschild radius | 1 passed |
| 20 | The Schwarzschild radius goes up in proportion to the mass: twice the mass, twice the radius. | Encyclopaedia Britannica: Black hole | 1 passed |
| 21 | For a star like the Sun, the Schwarzschild radius is about 3 km (2 miles). | Encyclopaedia Britannica: Schwarzschild radius | 1 passed |
| 22 | For a black hole with ten times the Sun’s mass, the radius would be 30 km (18.6 miles). | Encyclopaedia Britannica: Black hole | 1 passed |
| 23 | For something with the mass of a person it would be about 10⁻²³ cm, far smaller than the nucleus of an atom. | Encyclopaedia Britannica: Schwarzschild radius | 1 passed |
| 24 | Large black holes can trap tens to millions of times the Sun’s mass in a point smaller than the tip of a pin. | NASA Space Place: What is a black hole? | 1 passed |
| 25 | Fall too close and the black hole’s pull would squeeze you sideways and stretch you lengthways like a noodle. Scientists really do call it spaghettification. | NASA Science: 10 questions you might have about black holes | 2 passed |
| 26 | It has never happened to anyone: black holes are too far away to pull in any matter from our solar system. | NASA Science: 10 questions you might have about black holes | 2 passed |
| 27 | Scientists have watched black holes tear stars apart, which releases a tremendous amount of energy. | NASA Science: 10 questions you might have about black holes | 2 passed |
| 28 | All black holes spin. The fastest known, GRS 1915+105, turns more than 1,000 times a second. | NASA Science: Black holes (overview and essential facts) | 2 passed |
| 29 | A hidden black hole can be weighed from the stars around it: their speeds show how massive the dark object is. | NASA Science: 10 questions you might have about black holes | 1 passed |
| 30 | Black holes bend light from things behind them. This gravitational lensing can reveal lonely black holes that would otherwise be invisible. | NASA Science: Black holes (overview and essential facts) | 1 passed |
| 31 | Black holes are much studied but not fully understood. Nobody knows, for example, what matter looks like inside the event horizon. | NASA Science: Black holes (overview and essential facts) | 2 passed |
| 32 | Gas falling quickly into a black hole is thought to give off more than 100 times as much energy as the same mass would release by nuclear fusion. | Encyclopaedia Britannica: Black hole | 1 passed |
| 33 | The details of a black hole’s structure are worked out from Albert Einstein’s general theory of relativity. | Encyclopaedia Britannica: Black hole | 1 passed |
| 34 | Astronomers usually sort black holes by mass into three groups: stellar-mass, supermassive and intermediate-mass. The boundaries are only approximate. | NASA Science: Black hole types | 2 passed |
| 35 | When a star of more than eight times the Sun’s mass runs out of fuel, its core collapses, rebounds and explodes as a supernova. | NASA Science: Black hole types | 1 passed |
| 36 | NASA says that if the star had around 20 times the Sun’s mass or more, its core collapses into a stellar-mass black hole. Near the threshold, it makes a city-sized neutron star instead. | NASA Science: Black hole types | 2 passed |
| 37 | Britannica says only the most massive stars, those of more than three solar masses, become black holes. Smaller ones end as white dwarfs or neutron stars. | Encyclopaedia Britannica: Black hole | 1 passed |
| 38 | A stellar-mass black hole can probably form in seconds, after a massive star collapses. | NASA Science: 10 questions you might have about black holes | 1 passed |
| 39 | Newborn stellar black holes range from a few to hundreds of times the Sun’s mass. | NASA Science: Black hole types | 1 passed |
| 40 | Nearly all the stellar-mass black holes found so far were found because they are paired with a star. | NASA Science: Black hole types | 2 passed |
| 41 | Pairs like these have revealed around 50 suspected or confirmed stellar-mass black holes in the Milky Way, but there may be as many as 100 million in our galaxy. | NASA Science: Black hole types | 2 passed |
| 42 | The stellar black holes found in the Milky Way before 2024 averaged about 10 times the Sun’s mass. | ESO press release eso2408: Gaia BH3, the most massive stellar black hole in our galaxy (16 April 2024) | 1 passed |
| 43 | Almost every large galaxy, the Milky Way included, has a supermassive black hole at its centre, with hundreds of thousands to billions of times the Sun’s mass. | NASA Science: Black hole types | 2 passed |
| 44 | Some supermassive black holes formed in the first billion years after the birth of the universe. How they started is still a mystery. | NASA Science: Black hole types | 2 passed |
| 45 | Supermassive black holes grow by swallowing smaller objects, and by merging with each other when galaxies collide. | NASA Science: Black hole types | 1 passed |
| 46 | The black hole at the centre of the galaxy Holmberg 15A holds at least 40 billion times the Sun’s mass. | NASA Science: Black hole types | 1 passed |
| 47 | Intermediate-mass black holes, from about a hundred to hundreds of thousands of Suns, should exist, but the candidates have proved hard to confirm. | NASA Science: Black hole types | 2 passed |
| 48 | One candidate, 3XMM J215022.4−055108, has about 50,000 times the Sun’s mass. | NASA Science: Black hole types | 2 passed |
| 49 | Primordial black holes, if they exist, would have formed in the first second of the universe, with masses from 100,000 times less than a paperclip to 100,000 times more than the Sun. | NASA Science: Black hole types | 2 passed |
| 50 | Nobody has yet found definite proof that primordial black holes ever existed. | NASA Science: Black hole types | 1 passed |
| 51 | Theory says black holes with less mass than a mountain would evaporate faster than bigger ones, so many small early ones may have vanished completely. | NASA Science: Black hole types | 1 passed |
| 52 | The Sun will never become a black hole. It isn’t massive enough to explode, and will end its life as a white dwarf. | NASA Science: 10 questions you might have about black holes | 2 passed |
| 53 | The nearest known black hole, Gaia BH1, is about 1,500 light-years away. | NASA Science: Black holes (overview and essential facts) | 1 passed |
| 54 | Gaia BH3, announced in April 2024, has about 33 times the Sun’s mass and lies about 2,000 light-years away in the constellation Aquila, making it the second-closest known black hole. | ESO press release eso2408: Gaia BH3, the most massive stellar black hole in our galaxy (16 April 2024) | 2 passed |
| 55 | It was the first black hole of stellar origin this big ever spotted in the Milky Way. | ESA: Sleeping giant surprises Gaia scientists (16 April 2024) | 1 passed |
| 56 | Its companion is an ancient giant star that formed in the first two billion years after the Big Bang. | ESA: Sleeping giant surprises Gaia scientists (16 April 2024) | 1 passed |
| 57 | The most massive black hole yet observed, TON 618, has 66 billion times the Sun’s mass. | NASA Science: Black holes (overview and essential facts) | 1 passed |
| 58 | The lightest known black hole has only 3.8 times the Sun’s mass. It is paired up with a star. | NASA Science: Black holes (overview and essential facts) | 2 passed |
| 59 | NASA’s black hole page lists the most distant black hole detected, at the centre of the galaxy QSO J0313-1806, as around 13 billion light-years away. | NASA Science: Black holes (overview and essential facts) | 1 passed |
| 60 | A 2019 NASA article put the most distant black hole then known in a galaxy about 13.1 billion light-years from Earth, seen as it was about 690 million years after the Big Bang. | NASA Science: 10 questions you might have about black holes | 2 passed |
| 61 | Cygnus X-1, discovered in 1971, is a blue supergiant star and an invisible companion, a black hole, orbiting each other every 5.6 days. | Encyclopaedia Britannica: Black hole | 2 passed |
| 62 | In 2011 a NASA Chandra team gave the most precise mass yet for the Cygnus X-1 black hole: 14.8 times the Sun’s mass. | NASA Chandra X-ray Observatory: Cygnus X-1 (17 November 2011) | 1 passed |
| 63 | ESO’s 2024 press release says Cygnus X-1 reaches 21 solar masses. | ESO press release eso2408: Gaia BH3, the most massive stellar black hole in our galaxy (16 April 2024) | 1 passed |
| 64 | ESA’s 2024 release puts Cygnus X-1 at around 20 times the Sun’s mass. | ESA: Sleeping giant surprises Gaia scientists (16 April 2024) | 1 passed |
| 65 | Cygnus X-1 is about 6,070 light-years from Earth. | NASA Chandra X-ray Observatory: Cygnus X-1 (17 November 2011) | 1 passed |
| 66 | Its event horizon spins round more than 800 times a second. | NASA Chandra X-ray Observatory: Cygnus X-1 (17 November 2011) | 1 passed |
| 67 | Stephen Hawking lost a bet, first placed in 1974, that Cygnus X-1 did not contain a black hole. | NASA Chandra X-ray Observatory: Cygnus X-1 (17 November 2011) | 1 passed |
| 68 | The supermassive black hole at the centre of the Milky Way is called Sagittarius A*, said “ay-star”. | NASA Science: Black holes (overview and essential facts) | 1 passed |
| 69 | It has about 4 million times the mass of the Sun. | NASA Science: Black holes (overview and essential facts) | 1 passed |
| 70 | That is relatively small compared with the black holes in some other galaxies. | NASA Science: Black hole types | 1 passed |
| 71 | A NASA article puts Earth about 26,000 light-years from the Milky Way’s black hole. | NASA Science: 10 questions you might have about black holes | 1 passed |
| 72 | ESO’s 2022 press release says it is 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 |
| 73 | There is no danger of Earth being pulled in. | NASA Science: 10 questions you might have about black holes | 1 passed |
| 74 | It has probably already swallowed most or all of the stars that formed near it. | NASA Science: 10 questions you might have about black holes | 1 passed |
| 75 | From the early 1990s, Reinhard Genzel and Andrea Ghez each led a team that mapped the orbits of the brightest stars near the centre of our galaxy. | Nobel Prize: press release, Nobel Prize in Physics 2020 | 1 passed |
| 76 | Both teams found an extremely heavy, invisible object: around four million solar masses packed into a region no larger than our solar system. | Nobel Prize: press release, Nobel Prize in Physics 2020 | 1 passed |
| 77 | To see through the dust they used the world’s largest telescopes and new ways to correct for the blurring caused by Earth’s atmosphere. | Nobel Prize: press release, Nobel Prize in Physics 2020 | 2 passed |
| 78 | Genzel and Ghez shared half of the 2020 Nobel Prize in Physics “for the discovery of a supermassive compact object at the centre of our galaxy”. | Nobel Prize: press release, Nobel Prize in Physics 2020 | 1 passed |
| 79 | The Nobel committee said a supermassive black hole is the only explanation currently known. | Nobel Prize: press release, Nobel Prize in Physics 2020 | 1 passed |
| 80 | Andrea Ghez was born in New York City in 1965 and is a professor at the University of California, Los Angeles. | Nobel Prize: press release, Nobel Prize in Physics 2020 | 2 passed |
| 81 | Reinhard Genzel was born in 1952 in Bad Homburg vor der Höhe, Germany. | Nobel Prize: press release, Nobel Prize in Physics 2020 | 1 passed |
| 82 | NASA’s James Webb Space Telescope has seen bright flares and fainter flickers from Sagittarius A*. The flickers are so quick they must come from very close to the black hole. | NASA Science: Black holes (overview and essential facts) | 2 passed |
| 83 | On 12 May 2022 astronomers unveiled the first image of Sagittarius A*, made by the Event Horizon Telescope. | ESO press release eso2208: Astronomers reveal first image of the black hole at the heart of our galaxy (12 May 2022) | 2 passed |
| 84 | From Earth it looks about as big in the sky as a doughnut would 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 |
| 85 | The telescopes observed it on several nights in 2017, collecting data for hours at a time, like a long exposure on a camera. | ESO press release eso2208: Astronomers reveal first image of the black hole at the heart of our galaxy (12 May 2022) | 2 passed |
| 86 | Gas takes days to weeks to circle M87*, but only minutes to circle Sagittarius A*, so its glow kept changing while the telescopes watched: “a bit like trying to take a clear picture of a puppy quickly chasing its tail”. | ESO press release eso2208: Astronomers reveal first image of the black hole at the heart of our galaxy (12 May 2022) | 2 passed |
| 87 | The published picture is an average of the different images the team extracted. | ESO press release eso2208: Astronomers reveal first image of the black hole at the heart of our galaxy (12 May 2022) | 1 passed |
| 88 | More than 300 researchers from 80 institutes worked on it, rigorously, for five years. | ESO press release eso2208: Astronomers reveal first image of the black hole at the heart of our galaxy (12 May 2022) | 2 passed |
| 89 | The two pictured black holes look remarkably similar, even though ours is more than a thousand times smaller and less massive than M87*. | ESO press release eso2208: Astronomers reveal first image of the black hole at the heart of our galaxy (12 May 2022) | 1 passed |
| 90 | The size of the ring agreed closely with the predictions of Einstein’s general relativity. | ESO press release eso2208: Astronomers reveal first image of the black hole at the heart of our galaxy (12 May 2022) | 1 passed |
| 91 | Britannica gives Sagittarius A* a mass equivalent to more than 4,000,000 Suns. | Encyclopaedia Britannica: Black hole | 1 passed |
| 92 | On 10 April 2019 the Event Horizon Telescope team revealed the first direct visual evidence of a supermassive black hole and its shadow. | ESO press release eso1907: Astronomers capture first image of a black hole (10 April 2019) | 2 passed |
| 93 | It is the black hole at the centre of Messier 87, a massive galaxy in the Virgo cluster: 55 million light-years away, with 6.5 billion times the mass of the Sun. | ESO press release eso1907: Astronomers capture first image of a black hole (10 April 2019) | 2 passed |
| 94 | The Event Horizon Telescope linked eight radio telescopes on the ground into one virtual telescope the size of Earth. | ESO press release eso1907: Astronomers capture first image of a black hole (10 April 2019) | 2 passed |
| 95 | Its telescopes sat on volcanoes in Hawaii and Mexico, mountains in Arizona and Spain’s Sierra Nevada, in Chile’s Atacama Desert and in Antarctica. | ESO press release eso1907: Astronomers capture first image of a black hole (10 April 2019) | 1 passed |
| 96 | The telescopes were synchronised by a technique called very-long-baseline interferometry, using Earth’s rotation, and observed at a wavelength of 1.3 mm. | ESO press release eso1907: Astronomers capture first image of a black hole (10 April 2019) | 2 passed |
| 97 | Its sharpness, 20 micro-arcseconds, is enough to read a newspaper in New York from a café in Paris. | ESO press release eso1907: Astronomers capture first image of a black hole (10 April 2019) | 1 passed |
| 98 | More than 200 researchers worked on the first picture. | ESO press release eso1907: Astronomers capture first image of a black hole (10 April 2019) | 1 passed |
| 99 | Petabytes of raw data were combined by specialised supercomputers at the Max Planck Institute for Radio Astronomy and MIT Haystack Observatory. | ESO press release eso1907: Astronomers capture first image of a black hole (10 April 2019) | 1 passed |
| 100 | ALMA in Chile, with 66 high-precision antennas, was the most sensitive telescope in the network. | ESO press release eso1907: Astronomers capture first image of a black hole (10 April 2019) | 1 passed |
| 101 | The result was published in six papers in a special issue of The Astrophysical Journal Letters. | ESO press release eso1907: Astronomers capture first image of a black hole (10 April 2019) | 1 passed |
| 102 | Britannica says the M87 black hole, with six and a half billion Suns’ worth of mass, is only 38 billion km (24 billion miles) across. | Encyclopaedia Britannica: Black hole | 1 passed |
| 103 | The ring is brighter on one side because the black hole is spinning: light from material turning towards Earth is boosted. | Encyclopaedia Britannica: Black hole | 1 passed |
| 104 | The picture was made from data collected in 2017 and released in 2019. | Encyclopaedia Britannica: Black hole | 1 passed |
| 105 | Since 2017 the network has added the Greenland Telescope, the NOEMA array and the 12-metre telescope on Kitt Peak. | ESO press release eso2208: Astronomers reveal first image of the black hole at the heart of our galaxy (12 May 2022) | 1 passed |
| 106 | On 14 September 2015 gravitational waves were observed for the very first time. They came from a collision between two black holes. | Nobel Prize: press release, Nobel Prize in Physics 2017 | 2 passed |
| 107 | Both LIGO detectors, at Livingston, Louisiana, and Hanford, Washington, picked up the signal at 09:51 UTC. | LIGO Caltech: Gravitational waves detected 100 years after Einstein’s prediction (11 February 2016) | 2 passed |
| 108 | The two black holes were about 29 and 36 times the mass of the Sun, and the collision happened 1.3 billion years ago. | LIGO Caltech: Gravitational waves detected 100 years after Einstein’s prediction (11 February 2016) | 1 passed |
| 109 | About three Suns’ worth of mass was turned into gravitational waves in a fraction of a second, with a peak power about 50 times that of the whole visible universe. | LIGO Caltech: Gravitational waves detected 100 years after Einstein’s prediction (11 February 2016) | 2 passed |
| 110 | Livingston recorded it 7 milliseconds before Hanford, which showed that the source lay in the southern sky. | LIGO Caltech: Gravitational waves detected 100 years after Einstein’s prediction (11 February 2016) | 2 passed |
| 111 | In the final fraction of a second the two black holes collided at nearly half the speed of light. | LIGO Caltech: Gravitational waves detected 100 years after Einstein’s prediction (11 February 2016) | 1 passed |
| 112 | Gravitational waves are ripples in space-time. They are made whenever a mass speeds up, like an ice-skater spinning or a pair of black holes circling each other. | Nobel Prize: press release, Nobel Prize in Physics 2017 | 1 passed |
| 113 | LIGO measured a change thousands of times smaller than the nucleus of an atom as the wave passed Earth. | Nobel Prize: press release, Nobel Prize in Physics 2017 | 1 passed |
| 114 | Einstein predicted gravitational waves about a hundred years earlier, but was convinced they could never be measured. | Nobel Prize: press release, Nobel Prize in Physics 2017 | 2 passed |
| 115 | LIGO is a joint project of more than a thousand researchers from more than twenty countries. | Nobel Prize: press release, Nobel Prize in Physics 2017 | 1 passed |
| 116 | Rainer Weiss, Barry Barish and Kip Thorne won the 2017 Nobel Prize in Physics “for decisive contributions to the LIGO detector and the observation of gravitational waves”. | Nobel Prize: press release, Nobel Prize in Physics 2017 | 1 passed |
| 117 | The waves took 1.3 billion years to reach the LIGO detectors in the USA. | Nobel Prize: press release, Nobel Prize in Physics 2017 | 1 passed |
| 118 | Russell Hulse and Joseph Taylor’s pulsar, found in 1974, showed indirectly that gravitational waves exist, and won them the 1993 Nobel Prize in Physics. | LIGO Caltech: Gravitational waves detected 100 years after Einstein’s prediction (11 February 2016) | 2 passed |
| 119 | Collisions of neutron stars and black holes make bigger black holes quickly, and send out gravitational waves. | NASA Science: 10 questions you might have about black holes | 1 passed |
| 120 | Before Gaia BH3, black holes of 30-odd Suns had only been detected in distant galaxies, through gravitational waves picked up by the LIGO–Virgo–KAGRA collaboration. | ESA: Sleeping giant surprises Gaia scientists (16 April 2024) | 1 passed |
| 121 | In 1783 the clergyman and astronomer John Michell described ‘dark stars’ whose light could not reach us, in a letter to Henry Cavendish that the Royal Society published. | The Royal Society blog: Black holes, who didn’t see them first? (June 2019) | 2 passed |
| 122 | He worked out that a star as dense as the Sun but more than 500 times as wide would hold in its own light. | The Royal Society blog: Black holes, who didn’t see them first? (June 2019) | 1 passed |
| 123 | He suggested that such a hidden body might still be found from the movements of bright bodies circling it. | The Royal Society blog: Black holes, who didn’t see them first? (June 2019) | 1 passed |
| 124 | His idea was published more than 130 years before Einstein’s theory of gravity. | The Royal Society blog: Black holes, who didn’t see them first? (June 2019) | 1 passed |
| 125 | Michell never used the words ‘black hole’, and nor did Einstein. | The Royal Society blog: Black holes, who didn’t see them first? (June 2019) | 2 passed |
| 126 | Michell (1724–1793) was a British geologist and astronomer, counted among the fathers of seismology, the science of earthquakes. | Encyclopaedia Britannica: John Michell | 3 passed |
| 127 | In 1916 Karl Schwarzschild predicted that there could be collapsed stars that give out no radiation. | Encyclopaedia Britannica: Black hole | 1 passed |
| 128 | Schwarzschild found the first exact solution of Einstein’s equations of gravity, and laid the foundation of black hole theory. | Encyclopaedia Britannica: Karl Schwarzschild | 2 passed |
| 129 | Schwarzschild was born in Frankfurt am Main in 1873 and died in Potsdam on 11 May 1916, after falling fatally ill while serving in the German army in the First World War. | Encyclopaedia Britannica: Karl Schwarzschild | 2 passed |
| 130 | Einstein himself did not believe that black holes really exist. | Nobel Prize: press release, Nobel Prize in Physics 2020 | 1 passed |
| 131 | In January 1965, ten years after Einstein’s death, Roger Penrose proved that black holes really can form, and described them in detail. | Nobel Prize: press release, Nobel Prize in Physics 2020 | 1 passed |
| 132 | Penrose’s article is still regarded as the most important contribution to general relativity since Einstein. It won him half of the 2020 Nobel Prize in Physics. | Nobel Prize: press release, Nobel Prize in Physics 2020 | 2 passed |
| 133 | The Royal Society says the term ‘black hole’ was coined by the American physicist John Archibald Wheeler in 1967. | The Royal Society blog: Black holes, who didn’t see them first? (June 2019) | 1 passed |
| 134 | Britannica says Wheeler popularised the term black hole. | Encyclopaedia Britannica: John Archibald Wheeler | 1 passed |
| 135 | Wheeler (1911–2008) studied with Niels Bohr in Copenhagen and joined Princeton University in 1938. | Encyclopaedia Britannica: John Archibald Wheeler | 4 passed |
| 136 | With Charles Misner and Kip Thorne he wrote Gravitation (1973), a major textbook on Einstein’s relativity. | Encyclopaedia Britannica: John Archibald Wheeler | 1 passed |
| 137 | The physicist Stephen Hawking proposed that black holes also slowly shrink, because they lose tiny amounts of energy, now called Hawking radiation. | NASA Science: 10 questions you might have about black holes | 2 passed |
| 138 | For most black holes we know about, shrinking noticeably would take much longer than the entire age of the universe. | NASA Science: 10 questions you might have about black holes | 1 passed |
| 139 | Hawking also proposed that many tiny primordial black holes, perhaps no heavier than an asteroid, might have formed in the Big Bang. | Encyclopaedia Britannica: Black hole | 1 passed |
| 140 | Even bigger black holes, about 10 billion Suns each, are inferred at the centres of the nearby galaxies NGC 3842 and NGC 4889. | Encyclopaedia Britannica: Black hole | 2 passed |
| 141 | Black holes are not cosmic vacuum cleaners. They don’t suck in other matter: from far enough away, their gravity acts just like that of anything else with the same mass. | NASA Science: Black holes (overview and essential facts) | 2 passed |
| 142 | Black holes are not wormholes. They don’t give shortcuts between places in space, or portals to other dimensions or universes. | NASA Science: Black holes (overview and essential facts) | 1 passed |
| 143 | A black hole cannot eat a whole galaxy. Even a supermassive one’s reach is nowhere near big enough. | NASA Science: 10 questions you might have about black holes | 1 passed |
| 144 | If the Sun were swapped for a black hole of the same mass, the planets would stay in their orbits, though the solar system would get a lot colder. | NASA Science: Black holes (overview and essential facts) | 1 passed |
| 145 | The universe won’t all be swallowed: each black hole’s zone of strong gravity is small compared with a galaxy, and the universe is big and expanding. | NASA Science: 10 questions you might have about black holes | 2 passed |
| 146 | Black holes are not rare. Most galaxies the size of the Milky Way have a giant one at their centre. | NASA Science: Black holes (overview and essential facts) | 1 passed |
| 147 | The exploding stars that leave black holes behind spread elements needed for life, such as carbon, nitrogen and oxygen. In a sense, NASA says, we owe our existence to them. | NASA Science: 10 questions you might have about black holes | 2 passed |
| 148 | Which came first, the galaxy or its black hole, is still one of the great puzzles of the universe. | NASA Science: 10 questions you might have about black holes | 1 passed |
| 149 | Matter that falls in adds to the black hole’s mass. Its gravity doesn’t disappear from the universe. | NASA Science: 10 questions you might have about black holes | 2 passed |
| 150 | A quasar is a supermassive black hole with gas pouring in so fast that it gives out a thousand times more energy than its whole galaxy. | NASA Science: 10 questions you might have about black holes | 1 passed |
| 151 | Telescopes don’t see black holes themselves. They see what happens around them: hot gas, orbiting stars and bent light. | NASA Science: Black holes (overview and essential facts) | 1 passed |