What is the universe?
The universe is everything. It includes all of space, and all the matter and energy that space contains. It even includes time itself and, of course, it includes you.
Earth and the Moon are part of the universe, as are the other planets and their many dozens of moons. Along with asteroids and comets, the planets orbit the Sun. The Sun is one among hundreds of billions of stars in the Milky Way galaxy, and most of those stars have their own planets, known as exoplanets.
The Milky Way is but one of billions of galaxies in the observable universe — all of them, including our own, are thought to have supermassive black holes at their centers. All the stars in all the galaxies and all the other stuff that astronomers can’t even observe are all part of the universe. It is, simply, everything.
The star-forming nebula W51 is one of the largest "star factories" in the Milky Way galaxy. "Star factories" like this one can operate for millions of years. The cavernous red region on the right side of W51 is older, evident in the way it has already been carved out by winds from generations of massive stars (those at least 10 times the mass of our Sun). The dust and gas in the region are swept around even more when those stars die and explode as supernovas. On the nebula's younger left side, many stars are just beginning to clear away the gas and dust. Credit: NASA/JPL-Caltech
Though the universe may seem a strange place, it is not a distant one. Wherever you are right now, outer space is only 62 miles (100 kilometers) away. Day or night, whether you’re indoors or outdoors, asleep, eating lunch or dozing off in class, outer space is just a few dozen miles above your head. It’s below you too. About 8,000 miles (12,800 kilometers) below your feet — on the opposite side of Earth — lurks the unforgiving vacuum and radiation of outer space.
In fact, you’re technically in space right now. Humans say “out in space” as if it’s there and we’re here, as if Earth is separate from the rest of the universe. But Earth is a planet, and it’s in space and part of the universe just like the other planets. It just so happens that things live here and the environment near the surface of this particular planet is hospitable for life as we know it. Earth is a tiny, fragile exception in the cosmos. For humans and the other things living on our planet, practically the entire cosmos is a hostile and merciless environment.
How old is Earth?
Our planet, Earth, is an oasis not only in space, but in time. It may feel permanent, but the entire planet is a fleeting thing in the lifespan of the universe. For nearly two-thirds of the time since the universe began, Earth did not even exist. Nor will it last forever in its current state. Several billion years from now, the Sun will expand, swallowing Mercury and Venus, and filling Earth’s sky. It might even expand large enough to swallow Earth itself. It’s difficult to be certain. After all, humans have only just begun deciphering the cosmos.
While the distant future is difficult to accurately predict, the distant past is slightly less so. By studying the radioactive decay of isotopes on Earth and in asteroids, scientists have learned that our planet and the solar system formed around 4.6 billion years ago.
How old is the universe?
The universe, on the other hand, appears to be about 13.8 billion years old. Scientists arrived at that number by measuring the ages of the oldest stars and the rate at which the universe expands. They also measured the expansion by observing the Doppler shift in light from galaxies, almost all of which are traveling away from us and from each other. The farther the galaxies are, the faster they’re traveling away. One might expect gravity to slow the galaxies’ motion from one another, but instead they’re speeding up and scientists don’t know why. In the distant future, the galaxies will be so far away that their light will not be visible from Earth.
Put another way, the matter, energy and everything in the universe (including space itself) was more compact last Saturday than it is today.
Put another way, the matter, energy and everything in the universe (including space itself) was more compact last Saturday than it is today. The same can be said about any time in the past — last year, a million years ago, a billion years ago. But the past doesn’t go on forever.
By measuring the speed of galaxies and their distances from us, scientists have found that if we could go back far enough, before galaxies formed or stars began fusing hydrogen into helium, things were so close together and hot that atoms couldn’t form and photons had nowhere to go. A bit farther back in time, everything was in the same spot. Or really the entire universe (not just the matter in it) was one spot.
Don't spend too much time considering a mission to visit the spot where the universe was born, though, as a person cannot visit the place where the Big Bang happened. It's not that the universe was a dark, empty space and an explosion happened in it from which all matter sprang forth. The universe didn’t exist. Space didn’t exist. Time is part of the universe and so it didn’t exist. Time, too, began with the big bang. Space itself expanded from a single point to the enormous cosmos as the universe expanded over time.
What is the universe made of?
The universe contains all the energy and matter there is. Much of the observable matter in the universe takes the form of individual atoms of hydrogen, which is the simplest atomic element, made of only a proton and an electron (if the atom also contains a neutron, it is instead called deuterium). Two or more atoms sharing electrons is a molecule. Many trillions of atoms together is a dust particle. Smoosh a few tons of carbon, silica, oxygen, ice, and some metals together, and you have an asteroid. Or collect 333,000 Earth masses of hydrogen and helium together, and you have a Sun-like star.
For the sake of practicality, humans categorize clumps of matter based on their attributes. Galaxies, star clusters, planets, dwarf planets, rogue planets, moons, rings, ringlets, comets, meteorites, raccoons — they’re all collections of matter exhibiting characteristics different from one another but obeying the same natural laws.
Stirred, not shaken: How pebbles become planets
(Video) The Worlds outside the Solar System. The Exoplanets | ReYOUniverse
Scientists have begun tallying those clumps of matter and the resulting numbers are pretty wild. Our home galaxy, the Milky Way, contains at least 100 billion stars, and the observable universe contains at least 100 billion galaxies. If galaxies were all the same size, that would give us 10 thousand billion billion (or 10 sextillion) stars in the observable universe.
But the universe also seems to contain a bunch of matter and energy that we can’t see or directly observe. All the stars, planets, comets, sea otters, black holes and dung beetles together represent less than 5 percent of the stuff in the universe. About 27 percent of the remainder is dark matter, and 68 percent is dark energy, neither of which are even remotely understood. The universe as we understand it wouldn’t work if dark matter and dark energy didn’t exist, and they’re labeled “dark” because scientists can’t seem to directly observe them. At least not yet.
How has our view of the universe changed over time?
How has our view of the universe changed over time?
Human understanding of what the universe is, how it works and how vast it is has changed over the ages. For countless lifetimes, humans had little or no means of understanding the universe. Our distant ancestors instead relied upon myth to explain the origins of everything. Because our ancestors themselves invented them, the myths reflect human concerns, hopes, aspirations or fears rather than the nature of reality.
Several centuries ago, however, humans began to apply mathematics, writing and new investigative principles to the search for knowledge. Those principles were refined over time, as were scientific tools, eventually revealing hints about the nature of the universe. Only a few hundred years ago, when people began systematically investigating the nature of things, the word “scientist” didn’t even exist (researchers were instead called “natural philosophers” for a time). Since then, our knowledge of the universe has repeatedly leapt forward. It was only about a century ago that astronomers first observed galaxies beyond our own, and only a half-century has passed since humans first began sending spacecraft to other worlds.
In the span of a single human lifetime, space probes have voyaged to the outer solar system and sent back the first up-close images of the four giant outermost planets and their countless moons; rovers wheeled along the surface on Mars for the first time; humans constructed a permanently crewed, Earth-orbiting space station; and the first large space telescopes delivered jaw-dropping views of more distant parts of the cosmos than ever before. In the early 21st century alone, astronomers discovered thousands of planets around other stars, detected gravitational waves for the first time and produced the first image of a black hole.
With ever-advancing technology and knowledge, and no shortage of imagination, humans continue to lay bare the secrets of the cosmos. New insights and inspired notions aid in this pursuit, and also spring from it. We have yet to send a space probe to even the nearest of the billions upon billions of other stars in the galaxy. Humans haven’t even explored all the worlds in our own solar system. In short, most of the universe that can be known remains unknown.
The universe is nearly 14 billion years old, our solar system is 4.6 billion years old, life on Earth has existed for maybe 3.8 billion years, and humans have been around for only a few hundred thousand years. In other words, the universe has existed roughly 56,000 times longer than our species has. By that measure, almost everything that’s ever happened did so before humans existed. So of course we have loads of questions — in a cosmic sense, we just got here.
'All these worlds are yours'
Our first few decades of exploring our own solar system are merely a beginning. From here, just one human lifetime from now, our understanding of the universe and our place in it will have undoubtedly grown and evolved in ways we can today only imagine.
Next: The Search for Life: Are We Alone?
FAQs
What is the universe answer? ›
The universe is everything. It includes all of space, and all the matter and energy that space contains. It even includes time itself and, of course, it includes you. Earth and the Moon are part of the universe, as are the other planets and their many dozens of moons.
What are exoplanets answer? ›An exoplanet is a planet outside our solar system, usually orbiting another star. They are also sometimes called "extrasolar planets," "extra-" implying that they are outside of our solar system.
What is the space beyond our solar system called? ›The universe is a vast expanse of space that contains all of everything in existence. The universe contains all of the galaxies, stars, and planets. The exact size of the universe is unknown.
What is an exoplanet quizlet? ›A planet that orbits a star that is not our own Sun. ("Extrasolar" means "beyond the Sun.")
How do you ask for the Universe answers? ›- Ask Through Prayer. Manifest With Ken. ...
- Receive The Answers Through Meditation. The second step to getting answers from the Universe is to receive the answers through meditation. ...
- Follow Your Intuition.
The Universe is the largest unit in which we live. It is a collection of galaxies. There is only one Universe, and everything that exists, exists in this Universe itself. Was this answer helpful?
What is an exoplanet in simple terms? ›An exoplanet is any planet beyond our solar system. Most orbit other stars, but free-floating exoplanets, called rogue planets, orbit the galactic center and are untethered to any star.
What is an example of an exoplanet? ›Additionally, exoplanets are often named after the scientific instrument or project that discovered the exoplanet. For example, 51 Pegasi b is an exoplanet around the star 51 Pegasi in the constellation Pegasus.
How many planets are in the exoplanet system? ›A different planet, initially detected in 1988, was confirmed in 2003. As of 1 January 2023, there are 5,297 confirmed exoplanets in 3,904 planetary systems, with 850 systems having more than one planet.
What is beyond the universe called? ›Outside the bounds of our universe may lie a "super" universe. Space outside space that extends infinitely into what our little bubble of a universe may expand into forever. Lying hundreds of billions of light years from us could be other island universes much like our own.
How many universes are there? ›
In a new study, Stanford physicists Andrei Linde and Vitaly Vanchurin have calculated the number of all possible universes, coming up with an answer of 10^10^16.
Is it possible to go beyond our solar system? ›Five robotic spacecraft have sufficient velocity to escape the bounds of our solar system and travel into interstellar space, but only one—NASA's Voyager 1—has crossed that boundary so far. Voyager 1 transitioned into interstellar space in 2012. Voyager 2 likely will be next.
Why is it called an exoplanet? ›The prefix exo is short for extrasolar, meaning beyond the Sun, so exoplanets are just planets that orbit stars other than our Sun. As of October 1, 2020, we've discovered 4,354 exoplanets in 3,218 planetary systems.
What is an exoplanet and why are they important? ›Exoplanets are planets that orbit other stars. More than 5,000 exoplanets have been found to date. Scientists think that most stars have at least one exoplanet. These worlds are a prime target for the search for life beyond Earth.
What are the 3 types of exoplanets? ›So far scientists have categorized exoplanets into the following types: Gas giant, Neptunian, super-Earth and terrestrial.
Is 42 the answer to the universe? ›The number 42 is especially significant to fans of science fiction novelist Douglas Adams' “The Hitchhiker's Guide to the Galaxy,” because that number is the answer given by a supercomputer to “the Ultimate Question of Life, the Universe, and Everything.”
Why is the answer to the universe and everything 42? ›Forty-two is the ASCII code for the symbol * also known as the asterisk. This symbol is often thought to translate to anything or everything. In this instance, 42 = everything, the meaning of life.
How to pray for the universe? ›- Praise. I give praise to the universe. ...
- Gratitude. I thank you for allowing me to wake up this morning. ...
- Forgiveness. ...
- Protection and Blessings. ...
- The concept of “coolness” ...
- Directions.
Many religious persons, including many scientists, hold that God created the universe and the various processes driving physical and biological evolution and that these processes then resulted in the creation of galaxies, our solar system, and life on Earth.
How do you explain the universe to a child? ›The Universe is everything we can touch, feel, sense, measure or detect. It includes living things, planets, stars, galaxies, dust clouds, light, and even time. Before the birth of the Universe, time, space and matter did not exist.
What is the universe made up of? ›
The Universe is thought to consist of three types of substance: normal matter, 'dark matter' and 'dark energy'. Normal matter consists of the atoms that make up stars, planets, human beings and every other visible object in the Universe.
Is there life on an exoplanet? ›Theory of Life
The orbit must lie in the “habitable zone” where the exoplanet's surface is just the right temperature for liquid water to exist. Every form of life we know requires liquid water, so an exoplanet too close or too far from its host star is less likely to contain life.
Kepler-452b (sometimes quoted to be an Earth 2.0 or Earth's Cousin based on its characteristics; also known by its Kepler Object of Interest designation KOI-7016.01) is a super-Earth exoplanet orbiting within the inner edge of the habitable zone of the sun-like star Kepler-452 and is the only planet in the system ...
What are exoplanets and how did they form? ›How Do Exoplanets Form? Direct visual evidence shows that planets form from circumstellar disks of gas and dust around young stars. These disks, also known as protoplanetary disks, are difficult to observe, as they surround a star that is typically 100,000 times brighter than the disk.
What is the difference between a planet and an exoplanet? ›The Short Answer:
Planets that orbit around other stars are called exoplanets. All of the planets in our solar system orbit around the Sun. Planets that orbit around other stars are called exoplanets.
Known as Kepler 452b, the world is estimated to be a bit on the hefty side, at five times the mass of Earth, but it is receiving just 10% more heat and light than we do from its G-type star, just like our sun but 1.5 billion years older.
What exoplanet is most common? ›By looking at planet frequency compared to the mass ratios of planets and stars and the distances between them, they determined that cold, Neptune-mass worlds are likely to be the most common types of planets beyond the so-called snow line – the distance from a star beyond which water remains frozen during planetary ...
How many planets in the universe can we live on? ›Three (Venus, Earth, and Mars) out of eight planets might be able to support life. Based on recent discoveries of planets outside of our Solar System, it was estimated that 1 in 5 planets could exist in the habitable zone of their star: Average lifetime of a planet.
How many exoplanets are there 2022? ›In 2022, NASA surpassed 5,000 confirmed exoplanets(Opens in a new window), which are alien worlds beyond our solar system. These include a diversity of distant planets, including (perhaps rocky) super-Earths, gas giants like Jupiter, "ice giants" like Neptune, and beyond.
How many exoplanets are Earth like? ›NASA says that among over 5,000 identified extraterrestrial planets, over 200 could be similar to Earth.
Does the universe have a name? ›
Answer and Explanation: There is no current name for our Universe, other than simply "the Universe", although we have names for our own home in the cosmos. Earth is part of the solar system of planets revolving around our Sun. The Sun is one of hundreds of billions of stars in the Milky Way Galaxy.
What is the word for the end of the universe? ›The universe's end is "known as 'heat death,' where the universe will be mostly black holes and burned-out stars," Caplan explained in the statement.
What is it called when the universe ends? ›The Big Crunch is a hypothetical scenario for the ultimate fate of the universe, in which the expansion of the universe eventually reverses and the universe recollapses, ultimately causing the cosmic scale factor to reach zero, an event potentially followed by a reformation of the universe starting with another Big ...
Do we live in a multiverse? ›Some take this to be evidence of nothing other than our good fortune. But many prominent scientists—Martin Rees, Alan Guth, Max Tegmark—have taken it to be evidence that we live in a multiverse: that our universe is just one of a huge, perhaps infinite, ensemble of worlds.
How many dimensions exist? ›The world as we know it has three dimensions of space—length, width and depth—and one dimension of time. But there's the mind-bending possibility that many more dimensions exist out there. According to string theory, one of the leading physics model of the last half century, the universe operates with 10 dimensions.
What is our universe called? ›Universe is a name given to all the matter around us. Our universe is also called the cosmos. It is originally a greek word.
Will humans ever leave the Milky Way? ›The technology required to travel between galaxies is far beyond humanity's present capabilities, and currently only the subject of speculation, hypothesis, and science fiction. However, theoretically speaking, there is nothing to conclusively indicate that intergalactic travel is impossible.
How long would it take for humans to leave the solar system? ›One thousand years. That is the minimum length of time it would take us to get to the nearest star — Proxima Centauri — using current methods. But since we discovered that this star houses a potentially habitable planet, scientists have been more enthusiastic about the idea of interstellar travel than ever before.
How long would it take to travel beyond our solar system? ›Much of interstellar space is actually inside our solar system. It will take about 300 years for Voyager 1 to reach the inner edge of the Oort Cloud and possibly about 30,000 years to fly beyond it. Alpha Centauri is currently the closest star to our solar system.
Who named Earth? ›All of the planets, except for Earth, were named after Greek and Roman gods and godesses. The name Earth is an English/German name which simply means the ground. It comes from the Old English words 'eor(th)e' and 'ertha'.
What makes an exoplanet a super-Earth? ›
The planet lies within what astronomers call the habitable zone, with a temperature that could allow life to thrive there. The rocky planet is eight times the mass of Earth and known as a super-Earth. This is the name given to planets between the size of Earth and Neptune.
Why are planets named after gods? ›The English names for planets mostly come from the Romans, who borrowed their designations from gods and goddesses: Mercury was named for the messenger god because it appears to move so swiftly across the sky, Jupiter shares a title with the king of the gods because it's the solar system's giant, and so on.
What does an exoplanet need to support life? ›Life needs some water, but deserts show that even a little can be enough. Only a small amount of light from the central star is required to provide for photosynthesis. Some nitrogen must be present for life and the presence of oxygen would be a good indicator of photosynthesis and possibly complex life.
What interesting facts do scientists know about the exoplanet? ›- 01Scientists have discovered 4,187 exoplanets.
- 02These exoplanets are grouped into 3,105 systems (like our Solar system).
- 031 out of 5 sun-like stars have an exoplanet orbiting around it.
- 04In the Milky way alone, there could be 40 million exoplanets.
A potentially habitable exoplanet is a hypothetical type of planet that has liquid water and may support life. As of March 2020, a total of 55 potentially habitable exoplanets have been found.
How many exoplanets are in a star? ›Astronomers estimate that there is roughly one exoplanet per star in our galaxy. Of course, some stars have many planets – our own Sun has eight.
What are the 5 types of exoplanets? ›Five of the exoplanet types refer only to size (mass and diameter). In order, from smallest to biggest, they are rocky planets; super-Earths; mini-Neptunes; ice giants; and gas giants. Planets in the super-Earth and mini-Neptune size range may be ocean planets, having liquid-water oceans hundreds of kilometers deep.
What are the 3 types of universe? ›There are basically three possible shapes to the Universe; a flat Universe (Euclidean or zero curvature), a spherical or closed Universe (positive curvature) or a hyperbolic or open Universe (negative curvature).
What are 5 facts about the universe? ›- 10 Crazy Facts You Didn't Know About Space. ...
- SPACE IS COMPLETELY SILENT. ...
- THE HOTTEST PLANET IN OUR SOLAR SYSTEM IS 450° C. ...
- A FULL NASA SPACE SUIT COSTS $12,000,000. ...
- THE SUN'S MASS TAKES UP 99.86% OF THE SOLAR SYSTEM. ...
- ONE MILLION EARTHS CAN FIT INSIDE THE SUN. ...
- THERE ARE MORE TREES ON EARTH THAN STARS IN THE MILKY WAY.
The Secret of the Universe (1991) is a collection of seventeen scientific essays by American writer and scientist Isaac Asimov. It is the twenty-second and final of a series of books collecting essays from The Magazine of Fantasy & Science Fiction (F&SF). Asimov died in 1992.
How many universes exist? ›
We currently have no evidence that multiverses exists, and everything we can see suggests there is just one universe — our own.
How many how many universes are there? ›In a new study, Stanford physicists Andrei Linde and Vitaly Vanchurin have calculated the number of all possible universes, coming up with an answer of 10^10^16.
What makes up 90% of the universe? ›Today hydrogen is estimated to account for 90% of all atoms in the universe, and it is essential to the material world.
What makes up 70% of the universe? ›It turns out that roughly 68% of the universe is dark energy. Dark matter makes up about 27%. The rest - everything on Earth, everything ever observed with all of our instruments, all normal matter - adds up to less than 5% of the universe.
How did universe born? ›Our universe began with an explosion of space itself - the Big Bang. Starting from extremely high density and temperature, space expanded, the universe cooled, and the simplest elements formed. Gravity gradually drew matter together to form the first stars and the first galaxies.
Who created the God? ›We ask, "If all things have a creator, then who created God?" Actually, only created things have a creator, so it's improper to lump God with his creation. God has revealed himself to us in the Bible as having always existed. Atheists counter that there is no reason to assume the universe was created.
Who is the God of universe? ›Vishnu, Lord of the universe, is a Hindu God known to have reincarnated into more than one form called Avatars. In other words, he is recognizable through the faces of other gods who receive praise within the Hindu beliefs. Here we have sculptures of Vishnu and a few of his forms ranging 8th-19th century.
How did time start? ›The measurement of time began with the invention of sundials in ancient Egypt some time prior to 1500 B.C. However, the time the Egyptians measured was not the same as the time today's clocks measure. For the Egyptians, and indeed for a further three millennia, the basic unit of time was the period of daylight.