UNIVERSALLY KNOWN

UNIVERSAL MATTERS

Based on various cosmological techniques, the universe is estimated at about 13.7 billion years old, give or take about 200 million years. Put another way, if the years flashed by at a rate of one each second, the universe would already be about 47 years old.
Scientists believe that hydrogen comprises approximately 90 to 99 percent of all matter in the universe.
It is estimated by scientists that the universe contains 0.0000000000000000000000000000001 grams of matter per cubic centimeter of space. It is also estimated that the observable universe is 92 to 94 billion light years in diameter (if the observable universe is considered a sphere). Interestingly, it is possible that the universe is actually smaller than the observable universe. What is assumed to be very distant galaxies could in fact be duplicate images of other nearby galaxies created by light that has circumnavigated the universe. However, this is a difficult hypothesis to test because different images of a galaxy would show various time frames in its history, and therefore might appear dissimilar.
015GALAXY QUEST
It is estimated that, within the entire universe, there are more than a trillion galaxies.
 
Galaxies come in many different shapes, which are determined by the effects of past gravitational encounters with other galaxies. Our Milky Way is a spiral-type galaxy. Three-quarters of the galaxies in the universe are spiral galaxies. There are three other types of galaxies: elliptical, irregular, and lenticular.
 
The Milky Way galaxy is about 100,000 light-years in diameter, and our sun is estimated to be 26,100 light-years from the center. Our solar system lies halfway along the Orion arm of the Milky Way.
 
If you drove a car from Earth at a constant speed of 100 miles an hour, it would take about 221,000 million years to reach the center of the Milky Way. Yet our galaxy is minute compared to the radio galaxies being discovered at the edge of the known universe.
 
The Milky Way probably contains millions of old neutron stars that have stopped spinning, and so are undetectable.
 
Most scientists agree that there is likely a supermassive black hole at the center of our galaxy, weighing as much as 4 million suns. The black hole may be capturing stars, gas, and dust equivalent to the weight of three Earths every year. The Swedish Solar System is the world’s largest scale model of the solar system.
 
A galaxy of typical size—about 100 billion stars—produces less energy than a single quasar.
 
The Andromeda galaxy is the largest member of our local group of galaxies. The Milky Way is second largest in this group. The Andromeda galaxy is the most distant object visible to the naked eye. It is about 12 billion billion miles away.

MOON MYSTERIES

The moon is about 238,000 miles away from Earth. At that distance, it is Earth’s closest neighbor. Light from the moon takes about a second and a half to reach Earth.
The moon is about two-thirds as wide as the United States: 2,160 miles.
The moon weighs 81 billion tons.
Scientists have determined that most rocks on the surface of the moon are between 3 and 4.6 billion years old.
The moon orbits Earth every 27.32 days.
The dark spots on the moon that create the benevolent “man in the moon” image are actually basins filled three to eight kilometers deep with basalt, a dense mineral, which causes immense gravitational variations.
The temperature on the moon reaches 243°F at midday on the lunar equator. During the night, the temperature falls to -261°F.
Plenilune is an archaic term for a full moon.
The moon is 1 million times drier than the Gobi Desert.
The moon has about 3 trillion craters larger than three feet in diameter.
Mare Tranquillitatis, or Sea of Tranquillity, was the name of the basin on the first manned lunar landing. The Sea of Tranquillity is not a real sea, but a “maria,” one of the regions on the moon that appear dark when looking at it.
The largest moon crater visible from Earth is called Bailly, or the “fields of ruin.” It covers an area of about 26,000 square miles, about three times the size of Wales.
The moon does not have a global magnetic field.
The point in a lunar orbit that is farthest from the moon is called an apolune.
At the end of every 19 years, the lunar phases repeat themselves. In effect, the tide tables for the next 19 years will be approximately the same as those for the past 19 years.
Selenologists are those who study the moon.
Arthur C. Clarke, in 1959, made a bet that the first man to land on the moon would do so by June 1969. U.S. astronauts landed on July 20, 1969.
About 50 seconds’ worth of fuel remained when Apollo 11’s lunar module landed on the moon.
The footprints left by the Apollo astronauts will not erode since there is no wind or water on the moon and should last at least 10 million years.
The size of the first footprint on the moon was 13 by 6 inches, the dimensions of Neil Armstrong’s boot when he took his historic walk.
When the Apollo 12 astronauts landed on the moon, the impact caused the moon’s surface to vibrate for 55 minutes. The vibrations were picked up by laboratory instruments, leading geologists to theorize that the moon’s surface is composed of fragile layers of rock.
The multilayered space suit worn by astronauts on the Apollo moon landings weighed 180 pounds on Earth and 30 pounds on the moon with the reduced lunar gravity.
Even though there were only six manned lunar landings, there are seven Apollo lunar landers on the moon. Apollo 10, as part of their mission, dropped their lunar lander to test seismic equipment that had already been set up on a previous mission.
The first spacecraft to send back pictures of the far side of the moon was Luna 3 in October 1959. The photographs covered about 70 percent of the far side.
The final resting place for Dr. Eugene Shoemaker is the moon. The famed U.S. Geological Survey astronomer had trained the Apollo mission astronauts about craters, but never made it into space. Dr. Shoemaker had wanted to be an astronaut but was rejected because of a medical problem. His ashes were placed on board the Lunar Prospector spacecraft before it was launched on January 6, 1998. NASA crashed the probe into a crater on the moon on July 31, 1999, in an attempt to learn if there is water on the moon.
016SOLELY SOLAR
The sun is about 300,000 times larger than the Earth. The weight of the sun is estimated at 2 billion billion billion tons, about 333,420 times that of the Earth.
 
The sun’s surface area is 12,000 times that of Earth.
 
The sun contains over 99.8 percent of the total mass in our solar system, while Jupiter contains most of the rest. The fractional percentage that is left is made up of our Earth and moon and the remaining planets and asteroids.
 
The sun is a near-perfect sphere.
The sun is 93 million miles from Earth, yet it is 270,000 times closer than the next nearest star. It takes 8.5 minutes for light to get from the sun to Earth.
 
 
Although the sun is 400 times larger than the moon, it appears the same size in the sky because it is 400 times farther away.
 
The sun’s equator is 2.7 million miles around; it would take 3.6 billion people holding hands to go around it.
 
 
The sun is nearly 600 times bigger than all the planets combined.
 
An area of the sun’s surface the size of a postage stamp shines with the power of 1.5 million candles.
 
The sun produces more energy every minute than all the energy used on Earth in a whole year. Because it is pouring energy out into space so rapidly, the sun is shedding weight equivalent to that of a million elephants every second.
 
 
At its center, the sun has a density of over 100 times that of water. The pressure at the center of the sun is about 700 million tons per square inch. It’s enough to smash atoms, expose the inner nuclei and allow them to smash into each other, interact, and produce the radiation that gives off light and warmth. The sun has a core temperature of 154 million degrees Kelvin. If a pin was heated to the same temperature as the center of the sun, its heat would set alight everything within 60 miles of it.
 
The sun’s mass decreases by 4 million tons per second due to conversion of hydrogen to helium by thermonuclear reaction; this conversion will continue for approximately another 5 to 6 billion years before the sun’s hydrogen supply is exhausted and it enters its red giant phase.
 
All the coal, oil, gas, and wood on Earth would keep the sun burning for only a few days.
 
A spectroheliokinematograph is a special camera used to film the sun.
 
 
A sunbeam setting out through space at the rate of 186,000 miles a second would describe a gigantic circle and return to its origins after about 200 billion years.
 
Ancient Chinese astronomers first observed sunspots about 2,000 years ago. Westerners took quite a while to catch up, first writing of the dark blotches 1,700 years later, and wrongly believing them to be small planets. The smallest visible sunspots have an area of 500 million square miles, about 50 times the size of Africa. The largest sunspots have an area of about 7,000 million square miles.
 
 
The energy released in one hour by a single sunspot is equal to all the electrical power that will be used in the United States over the next million years.
 
The most ancient report of a solar eclipse is in Chinese records. The eclipse came without warning, according to legend, because the royal astronomers, Hsi and Ho, were too drunk to make the necessary computations. They were executed—the only astronomers known to have been killed for dereliction of duty.
 
 
There is a correspondence between the fluctuation of agricultural production and sunspot variations. Production of wheat, for example, reached high figures during sunspot maximums and low figures during sunspot minimums.
 
Giant flames called prominences shoot out from the sun’s surfaces for 310,000 miles, more than the distance from Earth to the moon. The entire Earth could fit into one of these flames nearly 40 times.
 
The sun gives off a stream of electrically charged particles called the solar wind. Every second the sun pumps more than a million tons of material into the solar wind. The solar wind flows past Earth at 1,200 times the speed of sound.
 
 
The sun’s solar wind is so powerful it has large effects on the tails of comets, and scientists have determined that it even has measurable effects on the trajectories of spacecraft.
 
 
A cosmic year is the amount of time it takes the sun to revolve around the center of the Milky Way, about 225 million years.
 
 
Galileo became totally blind shortly before his death, probably because of the damage done to his eyes during his many years of looking at the sun through a telescope.
 
Copernicus’s book, which suggested that the sun and not the Earth was the center of the solar system, was officially banned by the papacy until 1835.

SPACE TRAVELERS

Space dust is extremely small—smaller than a particle of smoke—and widely separated, with more than 320 feet between particles.
In the twentieth century, two objects hit the Earth’s surface with enough force to destroy a medium-size city. By pure luck, both landed in sparsely populated Siberia.
The average meteor, though brilliantly visible in the nighttime sky, is no larger than a grain of sand. Even the largest and brightest meteors, known as fireballs, rarely exceed the size of a pea.
More than 20 million meteoroids enter Earth’s atmosphere every day.
Millions of meteorites fall against the outer limits of the atmosphere every day and are burned to nothing by the friction.
It has been estimated that at least a million meteors have hit the Earth’s land surface, which is only 25 percent of the planet. Every last trace of more than 99 percent of the craters thus formed has vanished, erased by wind, water, and living things.
Five times as many meteors can be seen after midnight as can seen before.
The heaviest known meteorite to fall to Earth—the Hoba West meteorite—lies where it fell in Africa. Weighing about 60 tons, it is not likely to be moved.
Liquid water was found inside a 4.5-billion-year-old meteorite in 1999, giving scientists their first look at extraterrestrial water.
As of 2007 the present rate of discovery of asteroids in the solar system is about 5,000 per month.
More than 100,000 asteroids lie in a belt between Mars and Jupiter.
The largest asteroid on record is Ceres. It is so big it would stretch a distance of over 600 miles. It was also the first asteroid to be discovered.
The brightest asteroid is called Vesta. It has a diameter of 335 miles and is the only asteroid visible to the unaided eye. The Hubble Space Telescope recently discovered a huge 295-mile-wide crater on Vesta. This is massive when compared to Vesta’s 335-mile diameter. If Earth had a crater of proportional size, it would fill most of the Pacific Ocean basin.
In 1937 the tiny asteroid Hermes passed uncomfortably close to the Earth, at a distance of less than twice that of the moon. Astronomers later discovered that in 1942 it passed even closer. On March 23, 1989, a thousand-foot-wide asteroid missed impacting the Earth by only 400,000 miles, passing through the exact position the Earth was in six hours before. If it had hit the Earth, the resulting explosion would have been the largest in recorded history. And in 2002, another asteroid missed impacting the Earth by only 75,000 miles, or one-third the distance to the moon. Astronomers did not even discover the near-impact until three days later.
The word comet comes from the Greek komé, meaning “hair of the head.” Aristotle first used the deviation kometes, meaning “stars with hairs.”
In the history of the solar system, 30 billion comets have been lost or destroyed. That amounts to only 30 percent of the estimated number that remain.
There is now evidence that comets are propelled into the inner solar system by the tidal pull of the entire galaxy rather than by the pull of passing stars, as many astronomers had believed. And, just as the moon pulls the Earth’s oceans upward on a regular, predicable timetable, the galaxy’s pull on comets also follows a predictable pattern, causing greatly increased comet activity about once every 35 million years.
Until the mid-sixteenth century, comets were believed to be not astronomical phenomena, but burning vapors that had arisen from distant swamps and were propelled across the sky by fire and light.
In the sixteenth and seventeenth centuries, some people thought comets were the eggs or sperm of planetary systems.
Comets speed up as they approach the sun—sometimes reaching speeds of over 1 million miles per hour. Far away from the sun, speeds drop, perhaps down to as little as 700 miles an hour.
The tails of comets generally point away from the sun, whether the comet is approaching the sun or receding. The tail of a comet can extend 90 million miles—nearly the distance between the Earth and the sun.
The jets of water vapor discharged by a comet have a rocketlike effect. They alter the comet’s orbit enough to make its course unpredictable.
If one were to capture and bottle a comet’s 10,000-mile vapor trail, the amount of vapor actually present in the bottle would take up less than one cubic inch of space.
The huge halo of comets that surrounds our solar system is called the Oort Cloud.
Halley’s Comet, one of the most famous comets, returns to Earth every 76 years, and has been observed and recorded for more than three thousand years. Halley’s Comet is named after Edmond Halley, who was the first to suggest that comets were natural phenomena of our solar system, in orbit around the sun.
In 1066, Halley’s Comet appeared shortly before William the Conqueror invaded England. The Norman king took it as a good omen; his battle cry became “A new star, a new king.”
The nucleus of Halley’s Comet is a peanut-shaped object, weighing about 100,000 million tons and measuring about nine miles by five miles.
In 1994, the comet Shoemaker-Levy 9 broke apart and plunged into Jupiter, ripping holes the size of Earth in the planet’s atmosphere.

PLANETARIUM

The reflecting power of a planet or satellite, expressed as a ratio of reflected light to the total amount falling on the surface, is called the albedo.
Gold exists on Mars, Mercury, and Venus.
The existence of Mercury has been known since about the third millennium BC. The planet was given two names by the Greeks: Apollo, for its apparition as a morning star, and Hermes as an evening star. Greek astronomers knew, however, that the two names referred to the same body.
A solar day on Mercury, from sunrise to sunset, lasts about six Earth months or 176 Earth days. The big time difference is due to Mercury’s length of rotation, which is much slower than the Earth’s. A day on Mercury is twice as long as its year. Mercury rotates very slowly but revolves around the sun in slightly less than 88 days.
Mariner 10 was the first spacecraft to fly by Mercury. In 1974, it sent back close-up pictures of a world that resembles our moon.
Temperature variations on Mercury are the most extreme in the solar system, ranging from 90°K (Kelvin) to 700°K. At midday on Mercury, the sunlight is hot enough to melt lead. The surface of Venus is actually hotter than Mercury’s, despite being nearly twice as far from the sun. Lead melts at 662°F, and the surface can reach temperatures of 864°F.
The Venus day is also longer than the Venus year. The planet spins on its axis once every 243 Earth days and orbits the sun once every 224 Earth days.
The winds of Venus blow steadily at 109 miles an hour.
Carbon dioxide makes up 97 percent of Venus’s atmosphere.
The diameter of Venus is only about 400 miles less than that of the Earth.
Venus, Earth’s nearest planetary neighbor, at its closest to us, is 105 times farther away than our moon.
The oldest features on Venus appear to be no older than 800 million years.
Venus is much brighter than any other planet. At its brightest, it can cast shadow, and even be seen during the daytime.
The surface of Venus—millions of miles away and hidden by clouds of sulphuric acid—has been better mapped than the Earth’s seabed.
Venus has no magnetic field, perhaps because of its slow rotation. It also has no satellites, though in the distant past it may have had a moon.
Venus does not tilt as it goes around the sun, so it has no seasons. On Mars, however, the seasons are more exaggerated and last much longer than on Earth.
017EARTHLY DELIGHTS
Light takes one-tenth of a second to travel from New York to London, eight minutes to reach the Earth from the Sun, and 4.3 years to reach the Earth from the nearest star.
 
The Earth is the densest planet in the solar system.
 
The Earth orbits the sun at 18.5 miles a second.
Aristarchus, a Greek astronomer living about 200 BC, was reportedly the first person to declare that the Earth revolved around the sun. His theory was disregarded for hundreds of years.
 
Less than 50 percent of American adults understand that the Earth orbits the sun yearly, according to a basic science survey.
 
The Earth moves in its 585-million-mile orbit around the sun approximately eight times faster than a bullet travels.
 
 
The Earth spins faster on its axis in September than it does in March.
 
The pressure at the center of the Earth is 27,000 tons per square inch. At the center of the giant planet Jupiter, the pressure is three times as great.
 
 
The Earth weighs nearly 6,588,000,000,000,000,000,000, 000 tons.
 
 
If you could magnify an apple to the size of the Earth, the atoms in the original apple would each be about the size of an apple.
 
If the world were to become totally flat and the oceans distributed themselves evenly over the Earth’s surface, the water would be approximately two miles deep at every point.
 
A bucket filled with earth would weigh about five times more than the same bucket filled with the substance of the sun. However, the force of gravity is so much greater on the sun that a person weighing 150 pounds on Earth would weigh 2 tons on the sun.
 
Without using precision instruments, Eratosthenes measured the radius of the Earth in the third century BC, and came within 1 percent of the value determined by today’s technology.
 
The distance around Earth’s equator is 24,920 miles; it would take 33 million people holding hands to reach across distance.
 
 
The world is not round. It is an oblate spheroid, flattened at the poles and bulging at the equator.
 
The temperature of Earth’s interior increases by one degree every 60 feet down.
 
The first photo of Earth taken from space was shot from the Vanguard 2 in 1959.
 
 
Earth is the only planet not named after a god.
 
To reach outer space, you need to travel at least 50 miles from Earth’s surface.
Afternoon temperatures on Mars go up to about 80°F in some areas, and down to -190°F at night.
The largest volcano known is on Mars: Olympus Mons, 370 miles wide and 16 miles high, is almost three times higher than Mount Everest.
The moons of Mars are called Phobos and Deimos after two mythical horses that drew the chariot of Mars, the Roman god of war. Phobos is so close to its parent planet that it could not be seen by an observer standing at either of Mars’s poles. Phobos makes three complete orbits around Mars every day. Deimos rises and sets twice a day.
The atmosphere of Mars is relatively moist. However, because the atmosphere is thin, the total amount of water in the atmosphere is minimal. If all the water in the atmosphere of Mars was collected, it would probably fill only a small pond.
Mars takes 1.88 years to orbit the sun, so its seasons are about twice as long as those on Earth.
Statistically, UFO sightings are at their greatest number during those times when Mars is closest to the Earth.
An object weighing 100 pounds on Earth would weigh just 38 pounds on Mars.
Antarctica was used as a testing laboratory for the joint United States-Soviet Union mission to Mars because it has much in common with the red planet.
Jupiter is the largest planet, and it has the shortest day. Although Jupiter has a circumference of 280,000 miles, compared with the Earth’s 25,000 miles, Jupiter manages to make one turn in 9 hours and 55 minutes. However, its years are 12 times as long as the Earth’s.
Jupiter has no solid surface, only layers of gaseous clouds. It is composed mainly of hydrogen and helium.
All the planets in our solar system could be placed inside Jupiter. Jupiter is two and a half times larger than all the other planets, satellites, asteroids, and comets of our solar system combined.
Jupiter is so big and has such a large atmosphere that many astronomers think it almost became a star.
The Great Red Spot on Jupiter is a swirling hurricane of gases. The winds in the hurricane reach 21,700 miles per hour.
Jupiter has 16 moons, the largest of which is Ganymede, which looks like a cracked eggshell. Ganymede is bigger than Mercury, the smallest planet. It is 3,275 miles in diameter.
Metis is the innermost of Jupiter’s known satellites and was named after a Titaness who was the first wife of the Greek god Zeus, known later as Jupiter in Roman mythology.
Astronomers believe Jupiter’s moon Europa may have an ocean of liquid water beneath an ice cap.
Jupiter’s moon Adrastea is one of the smallest moons in our solar system. It measures about 12.4 miles.
There are seven rings surrounding Saturn. Each of the rings is made up of thousands of ringlets, which are made up of billions of objects of varying sizes from thirty-three-foot-wide icebergs to pinhead-small ice specks. Driving at 75 miles an hour, it would take 258 days to drive around one of Saturn’s rings.
Winds ten times stronger than a hurricane on earth blow around Saturn’s equator. Wind speeds can reach 1,100 miles an hour.
Titan, Saturn’s largest moon, is the only moon in our solar system to have an atmosphere. However, it cannot support life as its atmosphere is made of nitrogen and methane gas.
Uranus, the seventh planet from the sun, is tipped on its side so that at any moment one pole is pointed at the sun. The polar regions are warmer than the equator. At the poles, a day lasts for 42 Earth years, followed by an equally long night.
Uranus was only discovered 225 years ago, on March 13, 1781, by Sir William Herschel.
Uranus is visible to the naked eye.
Uranus has 15 known satellites.
The discovery of Neptune was announced in 1846. But, when astronomers checked previous records, they found the record of an observation of the planet as far back as 1795 by astronomers who, believing it to be a star, recorded the position routinely. Since Neptune’s discovery, it has made about three-quarters of one revolution of the sun.
Neptune is so remote that light from the sun—though traveling at 186,000 miles per second—takes more than four hours to reach the planet. By comparison, light from the sun takes only eight minutes to reach the Earth. From Neptune, the sun would only appear to be a very bright star.
Neptune is a maximum distance of 2.82 billion miles from the sun. The length of one of its days is 17 hours 6 minutes, and the length of one of its years is 165 Earth days.
Neptune has eight known satellites. The coldest place in the solar system is the surface of Neptune’s largest moon Triton, which has a temperature of -391°F, only 69°F above absolute zero.
Besides Earth, only Jupiter, Saturn, Uranus, and Neptune have known magnetic fields.
The average surface temperature of Uranus, Neptune, and Pluto is about -364°F, 11 times colder than inside a home freezer.
Small satellites within a planet’s rings are sometimes called “mooms.”
Scientists are still finding new planets, but not in our solar system. Recently a new planet was discovered orbiting the star Epsilon Eridani, which is only 10.5 light-years from the Earth.
018PLUTOPIA
In 2006, the International Astronomical Union (IAU), which decides the official names of all celestial bodies, voted overwhelmingly to change Pluto’s classification from “planet” to “dwarf planet,” making the official number of planets in the solar system eight. The decision came after a multiyear search for a scientific definition of “planet,” which had never had an official meaning before.
 
Pluto takes 248 Earth years to orbit the sun. For 20 of those years, it is closer to the sun than Neptune. Because of a large orbital eccentricity, Pluto was closer to the sun than Neptune between January 1979 and March 1999. The nature of its orbit, however, always prevents it from colliding with Neptune. Some astronomers believe Pluto’s strange and erratic orbit indicates that it was originally a moon of Neptune that somehow broke loose.
 
Traveling at the speed of 186,000 miles per second, light takes six hours to travel from Pluto to Earth.
 
To an observer standing on Pluto, the sun would appear no brighter than Venus appears in our evening sky.
Pluto’s one moon, Charon, is 12,200 miles from the planet and has a diameter of just 740 miles. First seen from Earth in 1978, tiny Charon is similar in size to Pluto. The two bodies orbit each other like a double planet, with the same sides permanently facing each other. Pluto and Charon are so close in proximity it is believed that they may share an atmosphere.

ASTRO ANSWERS

The telescope on Mount Palomar, California, can see a distance of 7,038,835,200,000,000,000,000 miles.
The largest number of telescopes in one city in the world is in Tucson, Arizona.
The largest refracting telescope is the 40-inch Yerkes telescope, built in 1897 and still in use. All larger telescopes are of the “reflecting” variety, using mirrors instead of lenses.
A space shuttle at liftoff develops more power than all the cars in England combined.
Neil Armstrong’s training space suit brought in $178,500 at auction. This was more than double its presale estimate.
On September 21, 1978, two Soviet cosmonauts set a space endurance record of 96 days.
When astronauts first shaved in space, their weightless whiskers floated up to the ceiling. A special razor had to be developed that drew the whiskers in like a vacuum cleaner.

TWINKLE, TWINKLE LITTLE STAR

In the Middle Ages, many people believed that stars were beams of light shining through the floor of heaven.
The brightness of a star is called its magnitude. The smaller the magnitude is, the brighter the star is.
When we look at the farthest visible star, we are looking 4 billion years into the past—the light from that star, traveling at 186,000 miles a second, has taken that many years to reach us.
Eighty-eight different constellations have been identified and named by astronomers.
There are 200 to 400 billion stars in the Milky Way galaxy. The sun is about midway in the scale of star sizes, but most are smaller ones. Only 5 percent of the stars in our galaxy are larger than the sun. (That’s still 5 billion larger stars.)
If you attempted to count the stars in a galaxy at a rate of one every second, it would take around 3,000 years to count them all.
On a clear night, more than 2,000 stars are visible to the naked eye.
Two of every three stars in the galaxy are binary, meaning pairs of stars are more common than single-star systems like our own.
About 40 novae erupt in our galaxy each year.
A typical nova explosion releases about as much energy as the sun emits in 10,000 years, or as much as in 121 nuclear bombs.
The layer of gas that spreads out from a nova explosion can travel at speeds of 5 million miles per hour.
A brown dwarf is a very small dark object, with a mass less than one-tenth that of the sun. They are “failed stars”—globules of gas that have shrunk under gravity, but failed to ignite and shine as stars.
If a red giant star was the size of an ordinary living room, its energy-generating core would be the size of the period at the end of this sentence.
It takes 100,000 years for a red giant to change into a white dwarf. By astronomical standards, this is practically instantaneous, a mere one-thousandth of the star’s life.
A white dwarf has a mass equal to that of the sun, but a diameter only about that of the Earth. A cupful of white dwarf material weighs about 22 tons, the same as five elephants.
An estimated 10,000 million stars in our galaxy have died and produced white dwarfs.
The smallest star found to date is a neutron star that has a diameter of 59 kilometers but a mass 10 times that of our sun. This star is more commonly known as a black hole.
American physicist John Wheeler coined the term “black hole” in 1967; before this the phenomena were known as “frozen stars.”
The gravitational pull of a black hole is so strong that, if a two-pound book were brought within 20 feet of a black hole, the book would weigh more than the entire world’s population combined.
A neutron star is the strongest magnet in the universe. The magnetic field of a neutron star is a million million times stronger than the Earth’s magnetism.
The force of gravity is very strong on a neutron star because of its amazing density. Your weight on a neutron star would be 10,000 million times greater than on Earth. If an astronaut tried to land on a neutron star, he or she would be crushed by the extremely strong force of gravity, and squashed into a thin layer less than one atom thick.
Some neutron stars spin 600 times a second, which is as fast as a dentist’s drill.
The surface temperature of a neutron star is about 1.8 million degrees Fahrenheit.
The first pulsar (a rotating neutron star that emits brief, sharp pulses of radio waves instead of the steady radiation associated with other natural sources), discovered in 1967, never varies in its timing by even as much as a hundred-millionth of a second. Its pulse is registered every 1.33730109 seconds. A pulsar’s neutrons are so densely packed together that, if one the size of a nickel landed on Earth, it would weigh approximately 100 million tons.
When the first pulsar signal was detected, it was thought that its signals might be a message from an alien civilization deep in space. The signal was jokingly labeled LGM, for “little green men.”
Quasars are amazingly bright objects. A quasar generates 100 times as much light as the whole of our galaxy in a space not much larger than our solar system.
A car traveling at a constant speed of 60 miles an hour would take longer than 48 million years to reach the nearest star (other than our sun), Proxima Centauri. This is about 685,000 average human lifetimes. Proxima Centauri is too small to be seen without a telescope. If you traveled to Proxima Centauri, the sun would appear to be a bright star in the constellation of Cassiopeia.
The brightest star in the night sky is Sirius. Also known as the Dog Star, it is 51 trillion miles from the Earth, or about 8.7 light-years. The second brightest star is Canopus, which is only visible in the Southern Hemisphere.
The star Alpha Herculis is 25 times larger than the circumference described by the Earth’s revolution around the sun.
The star Antares is 60,000 times larger than our sun. If our sun were the size of a softball, the star Antares would be as large as a house.
The star known as LP 327-186, a so-called white dwarf, is smaller than the state of Texas, yet so dense that if a cubic inch of it were brought to Earth, it would weigh more than 1.5 million tons.
The star Sirius B is so dense, a handful of it weighs about 1 million pounds.
The star Zeta Thaun, a supernova, was so bright when it exploded in 1054 that it could be seen during the day.
In the constellation Cygnus, there is a double star, one of whose components has such a high surface gravity that light cannot escape from it. Many astronomers believe Cygnus X-1 was the first “black hole” to be detected.
Barnard’s star is approaching the sun at a speed of 87 miles per second. By the year 11700, it will be the closest star to us, at a distance of about 3.8 light-years. However, because it is so dim, it will still not be visible to the naked eye.
The current North Star (the star best suited for navigation northward) is Polaris. Because the direction of Earth’s axis is constantly changing, the title gets passed along every couple of centuries. The next North Star will be Gamma Cephai around AD 3000. By the year AD 14000, the North Star will be Vega.
The most luminous star is probably Eta Carinae, which has a maximum luminosity of around 4 million times that of the sun.
The giant red star Betelgeuse—the red star in the shoulder of the constellation Orion—is 700 million miles across, about 800 times larger than the sun, or more than a quarter the size of our entire solar system. Light takes one hour to travel from one side of the giant star to the other.
The dense globules of gas from which stars are born are much larger than the stars they will form. In the Orion nebula, globules have been detected that are 500 times larger than the solar system.
The Veil nebula was formed by an explosion that took place over 30,000 years ago, when the first people lived on Earth.
The Hercules global cluster is the brightest cluster in the northern sky. It was discovered by English scientist Edmond Halley in 1714.
The Tarantula nebula is the largest known nebula. It is 160,000 light-years away. If it were as close to us as the Orion nebula, its light would cast shadows on Earth. It is thought to contain a huge star of over 1,000 times the mass of the sun, 10 times more massive than any star in the Milky Way.
The coldest place in the known universe is the Boomerang Nebula, about 5,000 light-years away.