Intellect Plus
Space
396 cards. Each one is a 40-second story with a five-minute read behind it. Page 6 of 7.
- Gas giants are mostly not gas, and they have no surfaceThe phrase gas giant was coined in 1952 by the science fiction writer James Blish, and it stuck despite being misleading. Deep inside Jupiter or Saturn the pressure is so great th…
- Most stars swell into giants when their core hydrogen runs outA giant star is not simply a big star. It is one that has used up the hydrogen in its core and puffed up, becoming far larger and brighter than a normal star of the same colour. T…
- Earth's pull is not the same everywhere, and Einstein says it isn't a pullDrop a hammer and a feather in a vacuum and they land together: in the same gravitational field, everything falls at the same rate whatever its mass or material. Yet the rate itse…
- Spacecraft steal a little of a planet's motion to speed upThrow a tennis ball at 30 kilometres an hour toward a train coming at 50, and it bounces back at 130. Spacecraft pull the same trick with planets: swinging close past a moving wor…
- Astronomers think today's giant elliptical galaxies began as spinning disksNo laboratory can build a galaxy, so astronomers test their ideas by checking whether a theory predicts the galaxies we actually see. The leading picture now runs backwards from i…
- In a galaxy cluster, the galaxies themselves are the smallest share of the massA galaxy cluster looks like a swarm of galaxies bound together, yet the galaxies move too fast for their own gravity to hold them. Scorching gas between them outweighs the galaxie…
- Hubble sorted galaxies with a tuning fork drawn from photographic platesIn 1926 Edwin Hubble sorted galaxies by how they looked on photographic plates: smooth ellipses, flat spirals, and lens-shaped galaxies in between. Drawn as a two-pronged fork, hi…
- Satellites hunting secret nuclear tests found the universe's biggest explosionsOn 2 July 1967 two American Vela satellites, launched to catch covert Soviet nuclear tests in space, recorded a flash of gamma rays unlike any bomb. It took decades to learn what …
- Ganymede, bigger than Mercury, may hold more water than EarthJupiter's moon Ganymede is the largest moon in the Solar System, wider than the planet Mercury. Beneath its icy crust lies an ocean that may contain more water than all of Earth's…
- Our Sun probably had thousands of sibling stars it has since lostAbout 4.6 billion years ago a fragment of a giant gas cloud collapsed, perhaps nudged by an exploding star. The Sun likely grew up in a crowded cluster of between one thousand and…
- An astronomer used wartime blackouts to peer toward the Milky Way's heartIn the early 1940s, Los Angeles went dark under wartime blackout rules, and Walter Baade seized the chance. Using the 100-inch Hooker Telescope on Mount Wilson, he found a gap abo…
- Edwin Hubble proved galaxies exist but refused to call them galaxiesHubble used Cepheid stars to show that spiral nebulae lie far beyond the Milky Way, settling one of astronomy's great arguments. Yet he kept calling them nebulae, and the word gal…
- On the equinox, day and night are not actually equalEquinox means equal night, yet on that date daylight wins. The Sun is a disc, so its top edge clears the horizon before its centre does, and the atmosphere bends light over the ho…
- The dwarf planet that demoted Pluto was nicknamed XenaEris earned its name. Found in 2005 and first hailed by NASA as a tenth planet, it forced astronomers to define the word planet for the first time, and the 2006 ruling demoted Plu…
- Rockets never actually need to reach escape velocity to leave EarthEscape velocity from Earth's surface is about 11.2 kilometres per second, but that figure only applies to an unpowered object thrown upward once. A rocket firing its engines, or a…
- Squeeze Earth to nine millimetres and it would become a black holeAny lump of matter crushed small enough would turn into a black hole. The threshold, called the Schwarzschild radius, grows with mass: about 3 kilometres for the Sun and a mere 9 …
- The first exoplanet evidence sat unrecognised in a 1917 photograph for a centuryIn 1917 Walter Adams recorded the spectrum of a white dwarf called Van Maanen 2. Only in 2016 did astronomers realise its odd chemistry probably came from a shredded planet rainin…
- Cosmic dust makes distant stars look redder, like a smoky sunsetStarlight crossing the galaxy runs a gauntlet of dust. The grains scatter and absorb blue light more readily than red, so faraway stars arrive dimmer and ruddier than they really …
- The whole universe may once have been warm enough for liquid waterFor roughly seven million years, starting about 10 million years after the Big Bang, the cosmic background glowed between the boiling and freezing points of water. Astrophysicist …
- More of Earth's fresh water sits in polar ice than in rivers, lakes and skyThe great ice sheets of the polar deserts lock away more water than all of Earth's groundwater, lakes, rivers and atmospheric moisture put together. It is one of many quirks of th…
- Why we do not get a solar eclipse at every new moonIf the Moon circled Earth in the same plane that Earth circles the Sun, every full moon would bring a lunar eclipse and every new moon a solar one. The two orbits are tilted again…
- The Sun's yearly path across the sky is why our day lasts 24 hoursEarth spins once relative to the stars in about 23 hours 56 minutes. Our day is four minutes longer because, as we orbit, the Sun creeps a little under one degree eastward each da…
- Edwin Hubble guessed wrong about what elliptical galaxies turn intoEdwin Hubble thought elliptical galaxies were an early stage that later evolved into spirals. That idea turned out to be false. Ellipticals are mostly old, red swarms of stars tha…
- A small icy moon of Saturn sprays an ocean into spaceNear the south pole of Enceladus, more than 100 geysers blast water vapour, salt crystals and ice grains off the moon at around 200 kilograms every second. Some of it snows back d…
- Why astronomers measure sky positions in hours rather than degreesA star's right ascension is written in hours, minutes and seconds, not degrees. The habit comes from how positions were first measured: by timing when each object crossed the meri…
- The Milky Way's biggest star cluster may be the heart of a swallowed galaxyOmega Centauri looks like the Milky Way's largest globular cluster. Astronomers now suspect it is something stranger: the leftover core of a dwarf galaxy, complete with a central …
- Pluto was not the first planet to be demoted, only the most famousIn the 1800s, Ceres was counted as a planet, and by around 1851 the tally had swollen to 23. Astronomers then invented the word asteroid and quietly reshuffled the list. Pluto's 2…
- The Pillars of Creation were once feared destroyed by a supernovaIn 2007, hot gas seen by the Spitzer Space Telescope hinted that a star exploding 8,000 to 9,000 years ago might already be tearing apart the famous Pillars of Creation. When Hubb…
- The Crab Nebula is the wreckage of a star seen shining by day in 1054In July 1054 Chinese astronomers logged a guest star in Taurus bright enough to see in daylight. It stayed visible without a telescope for about two years, then faded. Nearly nine…
- Britain could once see the Southern Cross, until Earth's wobble hid itAround the fourth millennium BC, people as far north as Britain could watch the whole Southern Cross rise. The slow wobble of Earth's axis then dragged it below European horizons,…
- Stephen Hawking bet against the first black hole, hoping he would loseIn 1975 Stephen Hawking wagered Kip Thorne that a bright X-ray source in the constellation Cygnus was not a black hole. It was an insurance policy: if black holes turned out not t…
- Every constellation is slowly coming apart, even Orion and the PloughThe stars in a constellation look like neighbours, yet most sit at wildly different distances from us and drift in their own directions. Give it tens or hundreds of thousands of y…
- How astronomers climb from radar pings to the edge of the universeNo single technique can measure every distance in space. Astronomers instead build a ladder: radar fixes the scale of the Solar System, geometry reaches nearby stars, and known-br…
- Everything visible today once fit inside a speck far smaller than an atomAll the matter and energy in every galaxy we can see was, in the first instant, squeezed into a region trillions of times smaller than a proton. Then space itself ballooned, doubl…
- A single particle from space once carried the punch of a thrown baseballIn 1991 detectors caught one subatomic particle carrying about 50 joules, roughly the energy of a baseball flying at 90 kilometres an hour. That so-called OMG particle belongs to …
- Einstein's self-described ugly fudge factor came back to explain an accelerating cosmosIn 1917 Albert Einstein bolted an extra term onto his equations to hold the universe still, and he disliked it from the start. Once the cosmos was found to be expanding, he droppe…
- Astronomers still pretend the stars are painted on a giant ballNobody thinks the stars are fixed to a shell anymore, yet astronomers map the whole sky as if they did. Treating the heavens as the inside of an enormous sphere throws away distan…
- The southern centaur holds our nearest stellar neighbours and a diamond starCentaurus packs in 281 stars visible without a telescope, more than any other constellation. Among them is Alpha Centauri, the closest star system to the Sun, and a white dwarf wh…
- Centaurus A shoots radio jets longer than a million light-yearsAt the heart of Centaurus A sits a black hole of 55 million suns, firing a jet whose inner portion races at roughly half light speed. The radio glow from that outflow stretches pa…
- Pulsing stars gave astronomers a ruler for the entire universeIn 1908 Henrietta Swan Leavitt noticed that among thousands of flickering stars in the Magellanic Clouds, the slower a Cepheid pulsed, the brighter it truly was. That single patte…
- Ceres was found on New Year's Day, then lost, then rescued by mathsGiuseppe Piazzi spotted a slow-moving point of light on 1 January 1801, fell ill, and watched it slip into the Sun's glare. Nobody could find it again until a 24-year-old Carl Fri…
- The cosmos made its first atoms only after 380,000 years of fogFor its first few hundred thousand years the universe was an opaque glowing plasma, too hot for electrons to settle around nuclei. Around 380,000 years after the Big Bang they fin…
- Comets are named for long hair and built like fried ice creamThe Greeks called them long-haired stars, and the word comet still carries that image. Up close, a comet's core is a loose clump of ice, dust and rock only kilometres wide, yet it…
- One W of stars has been a queen, a camel, and elk antlersGreeks saw a boastful queen chained to a spinning throne. Arab stargazers saw a camel's hump and a henna-dyed hand. Chinese astronomers saw a chariot and its whip, the Sámi an elk…
- Two orbiting bodies are easy to predict, but add a third and nobody canNewton showed that a planet and its star follow tidy, predictable paths. Add one more body and the neat formulas vanish. Henri Poincaré proved in the 1890s that no general exact s…
- Callisto's battered surface has barely changed in billions of yearsJupiter's moon Callisto wears the oldest, most crater-packed surface in the Solar System, with almost no sign of volcanoes or shifting plates. It orbits too far out to be kneaded …
- Before it was a dog, Canis Major was a Babylonian bow and arrowThe Greeks saw a hound trotting after Orion. Babylonian skywatchers around 1100 BC saw a weapon instead: Sirius was an arrow aimed at the hunter, and stars to its south formed the…
- Ibn Rushd travelled to Morocco to see a star hidden from CórdobaIn 1153 the philosopher Ibn Rushd journeyed from Córdoba to Marrakesh to watch Canopus, a brilliant star that never climbed above his home horizon. Seeing it appear as he moved so…
- An ancient Mexican building was angled to face the rising of CapellaAround 275 BC, builders at Monte Albán in Oaxaca set one structure, Building J, askew from everything around it. Its steps were aligned so that someone standing in its doorway wou…
- A nebula brighter than Orion's stays obscure because it hides down southThe Carina Nebula is four times larger than the celebrated Orion Nebula and even brighter. Yet few people in the Northern Hemisphere know it, because it sits deep in the southern …
- Statistics proved that many double stars are true partners, not coincidencesTwo stars that look close in the sky might simply line up by chance, one near and one far away. In 1767 the English clergyman John Michell tested that idea mathematically. Studyin…
- Einstein used his own theory to argue that black holes were impossibleIn 1939, Albert Einstein published a calculation meant to show that black holes could not exist. He assumed pressure or spin would always halt a collapsing star before it shrank t…
- Some of the brightest galaxies were first catalogued as flickering local starsAstronomers once listed several objects as irregular variable stars inside the Milky Way, brightening and fading without pattern. They turned out to be colossal galaxies billions …
- A trace of lithium proved brown dwarfs are failed starsTrue stars destroy their lithium quickly, because the heat needed to fuse hydrogen is also enough to burn it. So when a spectrum taken by the Keck telescope in 1995 showed a faint…
- A comet is both a celestial body and a celestial object at onceAstronomers draw a quiet line between a body and an object. A body is one tightly bound lump, such as a planet or star; an object can be a looser structure of many parts, such as …
- Astronomy began with farming calendars and still welcomes amateurs to discover cometsFew sciences let hobbyists make real discoveries, but astronomy does; amateurs with backyard telescopes still find new comets. That openness fits a field born from practical needs…
- Cecilia Payne found what stars are made of and was told to hedgeIn 1925 a doctoral student at Radcliffe, Cecilia Payne, showed that stars consist mostly of hydrogen and helium, nothing like Earth's rocky make-up. The result seemed so unlikely …
- Venus and Mars show how a planet's air can go badly wrongVenus should be chilly, with a calculated equilibrium temperature near −40 °C. Instead its surface sits close to 460 °C beneath air about 80 times denser than ours. Mars went the …
- Our galaxy's central bar may be a phase that comes and goesThe Milky Way has a bar of stars across its middle, like about two thirds of nearby spiral galaxies. Such bars appear to be temporary. Simulations suggest they grow, buckle under …
- The Moon does not orbit Earth's centre, and the Sun wobbles tooEarth and Moon actually circle a shared balance point, and it is not Earth's centre. That point sits about 4,671 km from the middle of our planet, roughly three quarters of the wa…