Other Solar Systems – Our Milky Way galaxy is just one of the billions of galaxies in the universe. Within it, there are at least 100 billion stars, and on average, each star has at least one planet orbiting it. This means there are potentially thousands of planetary systems like our solar system within the galaxy! Introduction Our Sun is one of at least 100 billion stars in the Milky Way, a spiral galaxy about 100,000 light-years across. The stars are arranged in a pinwheel pattern with four major arms, and we live in one of them, about two-thirds of the way outward from the center. Most of the stars in our galaxy are thought to host their own families of planets. The Milky Way galaxy is just one of the billions of galaxies in the universe.
- 1 How many other planets are there in the Universe?
- 2 How many galaxies are there in the Universe?
- 3 How far does space go?
- 4 What is larger than the universe?
How many solar systems are there in one universe?
Hint: The earth is only a single planet in a universe that is said to contain billions of objects like galaxies, stars, planets, moons, asteroids, comets, meteoroids, etc. These cosmic arrangements stretch up to 93.016 billion light-years which is the size of the known universe.
The galaxy in which our planet is contained is called the Milky Way and it alone stretches over 105,700 light-years. Within it, our solar system extends to 1.5 light-years and is centred around the sun. The Sun is a star is a sphere made up of hot plasma radiating energy and light. Complete answer: The National Aeronautics and Space Administration, commonly known as NASA, reported that the sun as we know is one of at least 2500 other stars with planets orbiting them found alone in our galaxy, the Milky Way.
The Milky Way contains around 100-400 billion stars and at least that many planets. Therefore, the presence of other planetary systems like our solar system is not only possible but highly probable. This means that there is an unknowable number of stars and planetary systems in the entire universe.
- However, because even the closest stars to our planetary system are located hundreds of light-years away, it will take years of advanced technological research to send probes and find definite answers to these questions.
- The Proxima Centauri is the nearest known planetary system which is 4.25 light-years away and is part of the constellation Centaurus.
Note: Our solar system is made up of various objects including eight planets namely Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune alongside dwarf planets (Pluto and Eris) and moons, minor planets, comets, etc.
How many total solar systems are there?
The Short Answer: Our planetary system is the only one officially called “solar system,” but astronomers have discovered more than 3,200 other stars with planets orbiting them in our galaxy. Our solar system is just one specific planetary system—a star with planets orbiting around it.
- Our planetary system is the only one officially called “solar system,” but astronomers have discovered more than 3,200 other stars with planets orbiting them in our galaxy.
- That’s just how many we’ve found so far.
- There are likely to be many more planetary systems out there waiting to be discovered! Our Sun is just one of about 200 billion stars in our galaxy.
That gives scientists plenty of places to hunt for exoplanets, or planets outside our solar system. But our capabilities have only recently progressed to the point where astronomers can actually find such planets. In this illustration, you can see three young planets tracing orbits around a star called HR 8799 that lies about 130 light-years from Earth. Image credit: Gemini Observatory Artwork by Lynette Cook
How many other planets are there in the Universe?
Starts With A Bang — January 17, 2022 In 1990, we only knew of the ones in our Solar System. Today, we know of thousands, and that’s just the tip of the iceberg. The planets and moons that formed in our own Solar System likely arose from a protoplanetary disk that developed instabilities, which then grew, and the largest survivors continued to attract the surrounding matter.
Thanks to planet-finding methods like stellar wobble, the transit method, direct imaging, and microlensing, we know of thousands of planets beyond our Solar System. Given the limitations of what we’re able to see and the physics of how planets are formed, we fully expect there are trillions of planets in the Milky Way alone. With an estimated ~2 trillion galaxies in our observable Universe, we can finally make an accurate estimate of the total number of planets. The enormity of cosmic “chances” for life may surprise you.
For most of history, our Solar System contained the only known planets. Although we now believe we understand how the Sun and our Solar System formed, this early view is an illustration only. When it comes to what we see today, all we have left are the survivors. What was around in the early stages was far more plentiful than what survives today, a fact that is likely true for every successful stellar system and also every failed star system in the Universe. Each star within each galaxy contains its own stellar system, and potentially, its own set of planets. For a long time, we didn’t know how many of these stars actually possessed planets or what the likelihood of planets of different masses were. Today, more than 30 years after the first exoplanet was discovered, we are closer than ever to understanding just how many planets populate our Universe. The surfaces of six different worlds in our Solar System, from an asteroid to the Moon to Venus, Mars, Titan, and Earth, showcase a wide diversity of properties and histories. While Earth is the only world known to host life, these other worlds may someday expand our current understanding of how frequently life arises. If we want to know how many planets there are in the Universe, one way to make such an estimate is to detect planets to the limits of an observatory’s capabilities, and then to extrapolate how many planets there would be if we viewed it with a limitless observatory. When a massive planet orbits its parent star, the star and planet will both orbit their mutual center of mass. Even if the planet is not directly observable, its presence, orbital period, and mass (multiplied by an uncertain angle-of-orbital-inclination) can be extracted simply by measuring the periodic motion of the parent star with the method of Doppler spectroscopy. Today, exoplanets that cannot be directly seen or imaged can still be detected through their gravitational influence on their parent star, which causes a periodic spectral shift that can be clearly observed. ( Credit : E. Pécontal) Meanwhile, transiting planets obscure a portion of their parent star’s light. When planets pass in front of their parent star, they block a portion of the star’s light: a transit event. By measuring the magnitude and periodicity of transits, we can infer the orbital parameters and physical sizes of exoplanets. When transit timing varies and is followed (or preceded) by a smaller-magnitude transit, it may indicate an exomoon as well, such as in the system Kepler-1625. The candidate rogue planet CFBDSIR2149, as imaged in the infrared, is a gas giant world that emits infrared light but has no star or other gravitational mass that it orbits. It is one of the only rogue planets known, and was only discoverable because its large-enough mass emits its own infrared radiation. When a gravitational microlensing event occurs, the background light from a star gets distorted and magnified as an intervening mass travels across or near the line-of-sight to the star. The effect of the intervening gravity bends the space between the light and our eyes, creating a specific signal that reveals the mass and speed of the planet in question. Although the Milky Way is full of stars, this stellar density map of the sky, constructed with data from the ESA’s space-based Gaia mission, is only accurate to the extent that visible light gives us accurate information. The ultraviolet and visible light emitted by the Milky Way’s stars is obscured by the light-blocking dust in our galaxy, requiring longer-wavelength views to reveal them. Rogue planets may have a variety of exotic origins, such as arising from shredded stars or other material, or from ejected planets from solar systems, but the majority should arise from star-forming nebula, as simply gravitational clumps that never made it to star-sized objects. The Hubble eXtreme Deep Field (XDF) may have observed a region of sky just 1/32,000,000th of the total, but was able to uncover a whopping 5,500 galaxies within it: an estimated 10% of the total number of galaxies actually contained in this pencil-beam-style slice. When starlight passes through a transiting exoplanet’s atmosphere, signatures are imprinted. Depending on the wavelength and intensity of both emission and absorption features, the presence or absence of various atomic and molecular species within an exoplanet’s atmosphere can be revealed through the technique of transit spectroscopy. The Drake equation is one way to arrive at an estimate of the number of spacefaring, technologically advanced civilizations in the galaxy or Universe today. However, it relies on a number of assumptions that are not necessarily very good, and contains many unknowns that we lack the necessary information to provide meaningful estimates for.
How many galaxies are there in the Universe?
How many galaxies are in the Universe? — March 8, 2022 Artist’s logarithmic scale conception of the observable universe. The Solar System gives way to the Milky Way, which gives way to nearby galaxies which then give way to the large-scale structure and the hot, dense plasma of the Big Bang at the outskirts.
Each line-of-sight that we can observe contains all of these epochs, but the quest for the most distant observed object will not be complete until we’ve mapped out the entire Universe. (: Pablo Carlos Budassi; Unmismoobjetivo/Wikimedia Commons) When you gaze up at the night sky, through the veil of stars and the plane of the Milky Way close by, you can’t help but feel small before the grand abyss of the Universe that lies beyond.
Even though nearly all of them are invisible to our eyes, our observable Universe, extending tens of billions of light years in all directions, contains a fantastically large number of galaxies within it. The exact number of galaxies out there has been a mystery, with estimates rising from the thousands to the millions to the billions, all as telescope technology improved. Our deepest galaxy surveys can reveal objects tens of billions of light years away, but even with ideal technology, there will be a large distance gap between the farthest galaxy and the Big Bang. At some point, our instrumentation simply cannot reveal them all.
Sloan Digital Sky Survey). In an ideal world, we’d simply count them all. We’d point our telescopes at the sky, cover the entire thing, collect every photon emitted our way, and detect every object that was out there, no matter how faint. With arbitrarily good technology and an infinite amount of resources, we’d simply measure everything in the Universe, and that would teach us how many galaxies are out there.
But in practice, that won’t work. Our telescopes are limited in size, which in turn limits how many photons they can collect and the resolutions they can achieve. There’s a trade-off between the faintness of an object you can see and how much of the sky you can take in at once. The stars and galaxies we see today didn’t always exist, and the farther back we go, the closer to perfectly smooth the Universe gets, but there is a limit to the smoothness it could’ve achieved, otherwise we wouldn’t have any structure at all today.
To explain it all, we need a modification to the Big Bang: cosmological inflation. (: NASA/ESA/A. Feild (STScI)) So what we can do, instead, is to view a clear portion of the Universe without intervening matter, stars, or galaxies as deeply as possible. The longer you stare at a single patch of sky, the more light you’ll collect and the more you’ll reveal about it.
We first did this in the mid-1990s with the Hubble Space Telescope, pointing at a patch of sky that was known to have practically nothing in it, and simply sit on that spot and let the Universe reveal what was present. The blank region of sky, shown in the yellow L-shaped box, was the region chosen to be the observing location of the original Hubble Deep Field image.
With no known stars or galaxies within it, in a region devoid of gas, dust, or known matter of any type, this was the ideal location to stare into the abyss of the empty Universe. (: NASA/Digitized Sky Survey; STScI) It was one of the riskiest strategies of all-time. If it failed, it would have been a waste of over a week of observing time on the newly-corrected Hubble Space Telescope, the most sought-after data collection observatory.
But if it succeeded, it promised to reveal a glimpse of the Universe in a way we had never seen before. We collected data for hundreds of orbits, across a multitude of different wavelengths, hoping to reveal galaxies that were fainter, more distant, and harder to see than any we had detected before. The original Hubble Deep Field image, for the first time, revealed some of the faintest, most distant galaxies ever seen. Only with a multiwavelength, long-exposure view of the ultra-distant Universe could we hope to reveal these never-before-seen objects.
- R. Williams (STScI), Hubble Deep Field Team/NASA) Everywhere we looked, in all directions, there were galaxies.
- Not just a few, but thousands upon thousands of them.
- The Universe wasn’t empty and it wasn’t dark; it was full of light-emitting sources.
- As far as we were capable of seeing, stars and galaxies were clumped and clustered everywhere.
But there were other limits. The most distant galaxies are caught up in the expansion of the Universe, causing distant galaxies to redshift past the point where our optical and near-infrared telescopes (like Hubble) could detect them. Finite sizes and observing times meant that only the galaxies above a certain brightness threshold could be seen. Only approximately 1000 stars are present in the entirety of dwarf galaxies Segue 1 and Segue 3, which has a gravitational mass of 600,000 Suns. The stars making up the dwarf satellite Segue 1 are circled here. If new research is correct, then dark matter will obey a different distribution depending on how star formation, over the galaxy’s history, has heated it.
- Marla Geha/Keck Observatory) So we could push past our technological limits from that mid-1990s image, but even so, we could never record all the galaxies.
- The best attempt we ever made was the Hubble eXtreme Deep Field (XDF), which represented a composite image of ultraviolet, optical, and infrared data.
By observing just a tiny patch of sky so small it would take 32 million of them to cover all the possible directions we could look, we accumulated a total of 23 days worth of data. Stacking everything together into a single image revealed something never-before seen: a total of approximately 5,500 galaxies. Various long-exposure campaigns, like the Hubble eXtreme Deep Field (XDF) shown here, have revealed thousands of galaxies in a volume of the Universe that represents a fraction of a millionth of the sky. But even with all the power of Hubble, and all the magnification of gravitational lensing, there are still galaxies out there beyond what we are capable of seeing.
- Teplitz and M.
- Rafelski (IPAC/Caltech), A.
- Oekemoer (STScI), R.
- Windhorst (ASU), and Z.
- Levay (STScI)) You might think, therefore, that we could estimate the number of galaxies in the Universe by taking the number we observed in this image and multiplying it by the number of such images it would take to cover the entire sky.
In fact, you can get a spectacular number by doing so: 5500 multiplied by 32 million comes out to an incredible 176 billion galaxies. But that’s not an estimate; that’s a lower limit. Nowhere in that estimate do the too-faint, too-small, or too-close-to-another galaxies show up. Galaxies comparable to the present-day Milky Way are numerous, but younger galaxies that are Milky Way-like are inherently smaller, bluer, more chaotic, and richer in gas in general than the galaxies we see today. For the first galaxies of all, this ought to be taken to the extreme, and remains valid as far back as we’ve ever seen.
the ingredients that make up the Universe,the right initial conditions that reflect our reality,and the correct laws of physics that describe nature,
we can simulate how such a Universe evolves. We can simulate when stars form, when gravity pulls matter into large enough collections to create galaxies, and to compare what our simulations predict with the Universe, both near-and-far, that we actually observe.
Perhaps surprisingly, there were more galaxies in the early Universe than there are today. But unsurprisingly, they’re smaller, less massive, and are destined to merge together into the old spirals and ellipticals that dominate the Universe we inhabit at present. The simulations that match best with reality contain dark matter, dark energy, and small, seed fluctuations that will grow, over time, into stars, galaxies, and clusters of galaxies.
Most remarkably, when we look at the simulations that match the observed data the best, we can extract, based on our most advanced understanding, which clumps of structure should equate to a galaxy within our Universe. A simulation of the large-scale structure of the Universe. Identifying which regions are dense and massive enough to correspond to galaxies, including the number of galaxies that exist, is a challenge that cosmologists are only now just rising to. (: Zarija Lukic/Berkeley Lab) When we do exactly that, we get a number that’s not a lower-limit, but rather an estimate for the true number of galaxies contained within our observable Universe. Two nearby galaxies as seen in the ultraviolet view of the GOODS-South field, one of which is actively forming new stars (blue) and the other which is just a normal galaxy. In the background, distant galaxies can be seen with their stellar populations as well.
Even though they’re rarer, there are still late-time galaxies actively forming massive amounts of new stars. (: NASA, ESA, P. Oesch (University of Geneva), and M. Montes (University of New South Wales)) Over time, galaxies merged together and grew, but small, faint galaxies still remain today. Even in our own Local Group, we’re still discovering galaxies that contain mere thousands of stars, and the number of galaxies we know of have increased to more than 70.
The faintest, smallest, most distant galaxies of all are continuing to go undiscovered, but we know they must be there. For the first time, we can scientifically estimate how many galaxies are out there in the Universe. The next step in the great cosmic puzzle is to find and characterize as many of them as possible, and understand how the Universe grew up.
Are there infinite galaxies?
2016 : WHAT DO YOU CONSIDER THE MOST INTERESTING RECENT NEWS? WHAT MAKES IT IMPORTANT? Many cosmologists now think our spatial universe is infinite. That’s news. It was only this year that I heard about it. I don’t get out as much as I used to. Thirty years ago it was widely believed that our spatial universe is the finite 3D hypersurface of a 4D hypersphere—analogous to being the finite 2D surface of a 3D sphere.
- Our underlying hypersphere was supposedly born, and began expanding, at the Big Bang.
- And eventually our hypersphere was to run out of momentum and collapse back into a Big Crunch—which might possibly serve as the seed for a new Big Bang.
- No yawning void of infinity, and no real necessity for a troublesome initial point in time.
Our own Big Bang itself may have been seeded by a prior Big Crunch. Indeed, we could imagine an endless pearl-string of successive hyperspherical universes. A tidy theory. But then experimental cosmologists found ways to estimate the curvature of our space, and it seems to be flat, like an endless plane, not curved like the hypersurface of a hypersphere.
- At most, our space might be “negatively curved,” like an endless hyperbolic saddle shape, but then it’s probably infinite as well.
- If you’re afraid of infinity, you might say something like this: “So, okay, maybe we’re in a vast infinite space, but it’s mostly empty.
- Our universe is just a finite number of galaxies rushing away from each other inside this empty infinite space—like a solitary skyrocket exploding and sending out a doomed shower of sparks.” But many cosmologists say, no, there are an infinite number of galaxies in our infinite space.
Where did all those galaxies come from? The merry cosmologists deploy a slick argument involving the relativity of simultaneity and the inflationary theory of cosmic inflation—and they conclude that, in the past, there was a Big Bang explosion at every single point of our infinite space.
Flaaash! An infinite space with infinitely many galaxies! Note that I’m not talking about some shoddy “many universes” theory here. I hate those things. I’m talking about our good old planets-and-suns single universe. And they’re telling us it goes on forever in space, and on forever into the future, and it has infinitely many worlds.
We aren’t ever going to see more than a few of these planets, but it’s nice to know they’re out there. So, okay, how does this affect me in the home? You get a sense of psychic expansion if you begin thinking in terms of an infinite universe. A feeling of freedom, and perhaps a feeling that whatever we do here does not, ultimately, matter that much.
You’d do best to take this in a “relax” kind of way, rather than in an “it’s all pointless” kind of way. Our infinite universe’s inhabited planets are like dandelion flowers in an endless meadow. Each of them is beautiful and to be cherished—especially by the little critters who live on them. We cherish our Earth because we’re part of it, even though it’s nothing special.
It’s like the way you might cherish your family. It’s not unique, but it’s yours. And maybe that’s enough. I know some of you are going to want more. Well, as far as I can see, we’re living in one of those times when cosmologists have no clear idea of what’s going on.
They don’t understand the start of the cosmos, nor cosmic inflation, nor dark energy, nor dark matter. You might say they don’t know jack. Not knowing jack is a good place to be, because it means we’re ready to discover something really cool and different. Maybe next year, maybe in ten, or maybe in twenty years.
Endless free energy? Antigravity? Teleportation? Who can say. The possibilities are infinite and the future is bright. It’s good to be an infinite world. : 2016 : WHAT DO YOU CONSIDER THE MOST INTERESTING RECENT NEWS? WHAT MAKES IT IMPORTANT?
How far does space go?
How Far Away is the Edge of the Universe? | Museum of Science, Boston We ask Museum educator Janine all your questions about how far away things are, from the Moon to the end of the universe, during this Pulsar podcast brought to you by #MOSatHome. We ask questions submitted by listeners, so if you have a question you’d like us to ask an expert, send it to us at [email protected].
ERIC: At the Museum of Science, we’re often asked how far away things are in space. The simple answer is, really, really far away. Today on Pulsar, we’ll get some more exact answers, starting with the closest things to our home planet and making our way out to the edge of the universe. And along the way, we’ll find out: how do we know how far away these things are? Thanks to Facebook Boston for supporting this episode of Pulsar.
I’m your host, Eric, And my guest today is Janine from our forums department. Janine, thanks so much for going on this journey through the universe with me. JANINE: Yeah, absolutely, happy to be here. ERIC: So let’s start with the closest natural object to us here on the Earth.
- How far away is the moon? JANINE: OK, so I’ll use a unit of measurement that you’re probably pretty familiar with.
- It’s about 238,855 miles on average, and I say on average, because the distance does change.
- The moon does not orbit the Earth in a perfect circle, but that’s kind of an abstract thing, and it doesn’t really mean anything to you, right? So if the Earth was the size of a basketball, the moon would be about the size of a tennis ball.
They would be about 23 feet, 9 inches apart, which is about 30 earths, which is crazy to me. ERIC: It’s further away than you would think. JANINE: It really is. I always think everything in space has more space than we expect it to, so even our closest neighbor is 30 times away the size we are.
- Everything that you put on a mission to go into space costs fuel, so the more fuel you have, so to go faster, would actually make you weigh more, so there’s this balance of power and efficiency, and you’re always trying to make it as light as possible.
- It was kind of more of a circle around the Earth and then a couple of circles around the moon and then a landing rather than a straight shot.
- ERIC: So we could have got there a little bit quicker than four days, but not too much quicker.
- JANINE: Yeah, I think they say, on average, over the course of all of the missions is about three days to get from Earth to the moon.
ERIC: So we haven’t sent any astronauts to the moon in nearly 50 years. Lately, they spend their time on the International Space Station. How far away from Earth’s surface is that? JANINE: So that’s actually a lot closer. It’s only about 254 miles away, and I was trying to figure out what cities on the Earth are at least in the US are close to that distance, and I figured out it’s about the distance if you were to fly from LA to Las Vegas.
- ERIC: And the next object on our list at the center of the solar system, the sun.
- How far away is that? JANINE: So sun is our closest star, and it’s 92 million miles away, which is crazy, and now we’re starting to get to these distances in space where talking about them in miles really doesn’t mean anything.
So actually, the average distance from the Earth to the sun is a unit that astronomers used called an astronomical unit, so we’ve just decided that, for math, it’s a lot easier to figure out, we’ll just say that the distance from the Earth to the sun is 1, and then all of our math can be easier.
- If you could travel at the speed of light, which you can’t because you’re made of mass, but if you could, it would take 8.3 minutes.
- The thing that blows my mind away about this is, since it takes eight minutes for light to travel, the sun could go out suddenly, and we wouldn’t know about it for eight minutes.
ERIC: Because it would take eight minutes for light to stop showing up on Earth. JANINE: Yeah, it’s crazy. ERIC: So jumping right out to the edge of our neighborhood, we often get asked how big the solar system is. So how far away is the edge of the solar system? Does it even have an edge? JANINE: OK, so it’s hard to talk about the solar system and what does it mean to be part of the solar system.
- We’re considering the things in the solar system to be the things that are most pulled on by the sun, and so that’s at the edge of the Oort cloud, and to go back to that unit of the astronomical unit, that’s about 100,000 astronomical units away.
- ERIC: So start on Earth, head past the sun, then go 100,000 times further than that before you leave the solar system.
- JANINE: Yeah, isn’t that nuts?
ERIC: It is. That’s already so far, and speaking of that, when we mentioned the outer part of the solar system, we get asked about the robots that we’ve sent deep into space. So how far away is the furthest spacecraft that we’ve launched from the earth? JANINE: OK, so I looked this up yesterday.
- So it’s a little bit further out now, but since we’re talking about astronomy, everything in astronomy has a big error range anyway, so that’s fine.
- Voyager 1, which was launched in 1977 is about 150 astronomical units away from the Earth.
- ERIC: So that’s wicked far, but it’s not anywhere close to leaving behind the effect of the sun’s gravity.
OK, so leaving the solar system behind, what’s the next closest star to us and how far away is it? And since this question comes up a lot how long would it take a rocket to get there? JANINE: So the closest star to us is actually part of a three star system.
The closest one of those three stars is Proxima Centauri, which is 4.22 light years away, and so if you could travel at the speed of light, it would take you 4.22 years to get there, but we can’t travel at the speed of light, so how long would it take Voyager 1 to get there? It would take over 73,000 years.
ERIC: So using current rocket technology, we’re just not going to get there any time soon. JANINE: No. No, space, as I think we’re going to establish in this podcast, is very big. ERIC: Now, before we continue our journey, this would be a good place to bring up a question we got from Sophie.
- The planets are pretty easy to measure, we’ve been to them all, we can see them moving, how can we measure the distance to stars and galaxies?
- JANINE: Yeah, so astronomers actually use a bunch of different tools, and we call it the distance ladder, although I like to think about it as if you had a bunch of yardsticks and you tried to tape them together and that first yardstick is really strong and by the end it’s bending over and not super great, because our error of knowing what is correct and how accurate something is increases as we use different steps on this ladder.
- But the first step that you can use is called parallax, and you can actually do an experiment with this right now if you want to.
You can hold a finger in front of your face and close your left eye and then close your right eye and look at what happens behind it. And you’ll notice that, with respect to the things behind it, it moves in front, just because there’s a little bit of distance between each eye.
- And so we can do that with stars, but not with our eyes, because that’s too small of a distance with respect to how far away stars are.
- ERIC: Yeah, stars don’t seem to move too much if you just go outside and wink at them back and forth a bunch of times.
- JANINE: Yeah, so what we can actually do is use the Earth in its orbit as that kind of blinking, and so if we go out and measure in June and then we go out and measure in December, now we’ve got six months apart so we’re halfway around the sun.
So we’ve got that entire distance, which is 2 AU, going back to that astronomical unit is the longest baseline we can get while we’re on Earth. And we can look at stars and see how they change with respect to the things behind them, and that’s how we can get a direct distance.
- ERIC: So parallax seems pretty good for stars that are fairly close, but you mentioned other methods too.
- So what’s next? JANINE: Yeah, so the next step is something called a standard candle, and actually the first standard candle was discovered not too far from the Museum of Science by Henrietta Swann Levitt at the Harvard College Observatory back in the early 1900s.
She was a computer there. If you’re interested in this at all, there’s a really good book called The Glass Universe that talks about all of these computers who worked at the Harvard College Observatory, including Annie Jump Cannon, who’s very famous for figuring out the brightness of stars, a relationship about that.
- Henrietta Swan Levitt determined this first standard candle.
- So she was working at the Harvard College Observatory, examining photographic plates from telescopes.
- So these telescopes were taking all these images and they needed people to reduce the data, which is something that a lot of physical computers do now, but people did back then.
And she was looking at a particular type of star called a Cepheid variable, and she realized that there was some sort of a relationship between how fast they dimmed and brightened and what their brightness was. These Cepheid variables are very consistent, so she had this idea that, because luminosity and period are the same, maybe they could be used to figure out how far away something is.
So the standard candle idea is that a candle has an intrinsic brightness that we know. We can determine it because of some sort of physical relationship or just studying physics in general. This star, if we know this other thing about it, we know how bright it is if you were standing at a certain distance from it.
OK, so if we know how bright it should be and we know how bright we’re observing it, we can actually figure out the distance based on that, right? If you know how bright your flashlight is and you know how bright you’re seeing it, you can figure out how far away it is.
ERIC: So the further away something is, the dimmer it appears to us, and if we know its true brightness, it’s pretty easy math to calculate how far away it must be to appear how we see it. JANINE: Yeah, exactly. So they figured out that these Cepheid variables could be used in this way as a standard candle.
Although, my personal favorite standard candle is a type 1A supernova.
- And that’s entirely because, when I was in college, I worked on a project on SS Cygni, which is a very well known cataclysmic variable.
- And what a cataclysmic variable is is it’s a red giant star, and it has a partner a star, a binary star companion, called a white dwarf, and actually, most stars in the galaxy are in multiple star systems, so it’s pretty normal to find a binary star system.
- So in a cataclysmic variable, you have this red giant and you had this white dwarf, and the white dwarf is close enough to the red giant that it steals mass from the red giant.
- It doesn’t know what that mass belongs to and it takes it on and it turns into this disk that goes around the white dwarf and there is a point at which there’s too much mass in the disk, it becomes unstable, it all falls on to the white dwarf and the white dwarf brightness suddenly.
- And because we know what that mass is, there’s a mathematical physical relationship between how much mass is in that disk.
You then know how bright it is. You’ve got your E equals mc squared, so you know how much mass is going to turn into an energy, and then you can figure out how far away is. ERIC: And this takes us even further out on the distance ladder, because these things are so bright, we can see them from really far away and we can measure larger distances.
JANINE: Yeah. Yeah, and actually, that’s how we got our first distance to the Andromeda galaxy was Edwin Hubble, who you may have heard of because of a certain telescope. There was a person that that’s named after. So Edwin Hubble in 1924 used Cepheid variables that, as Henrietta Swan Levitt had posited you could, to figure out how far away the Andromeda nebula was, because at that point they didn’t know that galaxies were galaxies.
But he used it to prove that it wasn’t inside of the Milky Way, and his number was about 900,000 light years. He used 12 Cepheids to figure that out. We now think it’s about 2.537 million light years, but. ERIC: So in the ballpark, not too bad for telescopes from 100 years ago.
- JANINE: It’s astronomy, right? So it’s pretty close.
- ERIC: All right, we can use these methods to estimate distances to other galaxies that make up the universe, and now, we’re at the end of our journey.
- How far away is the edge of the universe? JANINE: This one’s harder.
- There isn’t an edge to the universe, at least not one that we know of, and people who are trying to figure out this are actually called cosmologists.
So there are people who study what the shape of the universe is, how big it is, how it formed, all of these kinds of things. But we can talk about the edge of the visible universe or actually how far back in time, we can see. We talked about that time limit and how long it would take light from the sun to get to the earth and how we wouldn’t know for eight minutes.
- Well, that applies to everything that we see in space, which means looking out into space is basically a time machine, right? We’re looking back in time the further out we go because it takes time for light to travel to us.
- So the furthest out we can see is about 46.5 billion light years away, which is crazy, but it also means you can look back into the past and try to figure out how the universe formed, which again, is what cosmologists do.
ERIC: Well, Janine, thanks so much for telling us how far away everything in the universe is. JANINE: You are so, so welcome. ERIC: You can find out more about the structure of the universe by tuning in to one of our virtual planetarium shows from the comfort of your own home.
How many Suns are in the Milky Way?
The Milky Way has a mass of 1.5 trillion suns. We have no idea what most of it is made of. By Updated Aug 20, 2019, 10:46am EDT Something weird is happening in our galaxy: It’s spinning fast enough that stars ought to be flying off, but there’s something holding them together.
- The substance that acts as a gravitational glue is dark matter.
- Yet it’s incredibly mysterious: Because it doesn’t emit light, no one has ever directly seen it.
- And no one knows what it’s made of, though there are plenty of wild hypotheses,
- For our galaxy — and most others — to remain stable, physicists believe there’s much, much more dark matter in the universe than regular matter.
But how much? Recently astronomers using the Hubble Space Telescope and the European Space Agency’s Gaia star map attempted to calculate the mass of the entire Milky Way galaxy. It’s not an easy thing to do. For one, it’s difficult to measure the mass of something we’re inside of. Their answer: The galaxy weighs around 1.5 trillion solar masses. This number helps put in perspective how very small we are. Take, for instance, where stars in the Milky Way fit in. If you’re lucky enough to get a completely dark, clear sky for stargazing, it’s possible to behold as many as 9,000 stars above you.
- That’s how many are visible to the naked eye.
- But another 100 billion stars (or more ) are out there just in our own Milky Way galaxy — yet they’re just 4 percent of all the stuff, or matter, in the galaxy.
- Another 12 percent of the mass in the universe is gas (planets, you, me, asteroids, all of that is negligible mass in the grand accounting of the galaxy).
The remaining 84 percent of the matter in the galaxy is the dark matter, Laura Watkins, a research fellow at the European Southern Observatory, and a collaborator on the project, explains. The enormity of the galaxy, and the enormity of the mystery of what it’s made of, is really hard to think through.
- So, here, using the recent ESA-Hubble findings, we’ve tried to visualize the scale of the galaxy and the scale of the dark matter mystery at the heart of it.
- As a visual metaphor, we’ve constructed a tower of mass.
- You’ll see that all the stars in the galaxy just represent a searchlight at the top of the building.
The vast majorities of the floors, well, no one knows what goes on in there.
How big is the universe?
Universe – Wikipedia Everything in space and time For other uses, see, Universe The image shows some of the most remote visible with present technology, each consisting of billions of stars. (Apparent image area about 1/79 that of a full moon) (within )13.799 ± 0.021 billion years DiameterUnknown. Diameter of the : 8.8 × 10 26 m (28.5 G or 93 G) Mass (ordinary matter)At least 10 53 kg Average density (including the contribution from )9.9 x 10 −30 g/cm 3 Average temperature2.72548 (-270.4 or -454.8 ) Main contents (4.9%) (26.8%) (68.3%) Shape with a 0.4% margin of error The universe (: universus ) is all of and and their contents, including,,, and all other forms of and,
The theory is the prevailing description of the development of the universe. According to this theory, space and time emerged together 13.787 ± 0.020 billion years ago, and the universe has been expanding ever since the Big Bang. While the spatial size of the entire universe is unknown, it is possible to measure the size of the, which is approximately 93 billion in diameter at the present day.
The earliest of the universe were developed by and and were, placing at the center. Over the centuries, more precise astronomical observations led to develop the with the at the center of the, In developing the, built upon Copernicus’s work as well as ‘s and observations by,
- Further observational improvements led to the realization that the Sun is one of a few hundred billion stars in the, which is one of a few hundred billion galaxies in the universe.
- Many of the stars in a galaxy,
- Galaxies are distributed uniformly and the same in all directions, meaning that the universe has neither an edge nor a center.
At smaller scales, galaxies are distributed in and which form immense and in space, creating a vast foam-like structure. Discoveries in the early 20th century have suggested that the universe had a beginning and that since then at an increasing rate. According to the Big Bang theory, the energy and matter initially present have become less dense as the universe expanded.
After an initial accelerated expansion called the at around 10 −32 seconds, and the separation of the four known, the universe gradually cooled and continued to expand, allowing the first and simple to form. gradually gathered, forming a -like structure of and under the influence of, Giant clouds of and were gradually drawn to the places where dark matter was most, forming the first galaxies, stars, and everything else seen today.
From studying the movement of galaxies, it has been discovered that the universe contains much more than is accounted for by visible objects; stars, galaxies, nebulas and interstellar gas. This unseen matter is known as dark matter ( dark means that there is a wide range of strong that it exists, but we have not yet detected it directly).
- The model is the most widely accepted model of the universe.
- It suggests that about 69.2% ± 1.2% of the mass and energy in the universe is a (or, in extensions to ΛCDM, other forms of, such as a ) which is responsible for the current, and about 25.8% ± 1.1% is dark matter.
- Ordinary (”) matter is therefore only 4.84% ± 0.1% of the physical universe.
Stars, planets, and visible gas clouds only form about 6% of the ordinary matter. There are many competing hypotheses about the and about what, if anything, preceded the Big Bang, while other physicists and philosophers refuse to speculate, doubting that information about prior states will ever be accessible.
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What planet is most like Earth?
Which planet is most similar to Earth? (Intermediate) – Curious About Astronomy? Ask an Astronomer I was just curious; What planet is most like Earth. In composition, size, in atmosphere, etc? Venus and Mars are the most like Earth, but in different ways. In terms of size, average density, mass, and surface gravity, Venus is very similar to Earth. But Mars is the planet that is most similar to Earth in other ways. Chris studies the large scale structure of the universe using the peculiar velocities of galaxies. He got his PhD from Cornell in 2005, and is now a Research Assistant Professor at the, : Which planet is most similar to Earth? (Intermediate) – Curious About Astronomy? Ask an Astronomer
What is larger than the universe?
Is there anything bigger than the universe? No, the universe contains all solar systems, and galaxies. Our Sun is just one star among the hundreds of billions of stars in our Milky Way Galaxy, and the universe is made up of all the galaxies – billions of them. Anonymous } LIVE Points 348 Rating Help make Alexa smarter and share your knowledge with the world : Is there anything bigger than the universe?
What is bigger than a galaxy?
From largest to smallest they are: Universe, galaxy, solar system, star, planet, moon and asteroid.
Can we travel to another galaxy?
Intergalactic travel is the hypothetical crewed or uncrewed travel between galaxies, Due to the enormous distances between the Milky Way and even its closest neighbors —tens of thousands to millions of light-years —any such venture would be far more technologically and financially demanding than even interstellar travel,
- Intergalactic distances are roughly a hundred-thousandfold (five orders of magnitude) greater than their interstellar counterparts.
- 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. There are several hypothesized methods of carrying out such a journey, and to date several academics have studied intergalactic travel in a serious manner.
What is the 9 planets name?
Types of planets in the solar system – The inner four planets closest to the sun — Mercury, Venus, Earth and Mars — are often called the ” terrestrial planets ” because their surfaces are rocky. Pluto also has a rocky, albeit frozen, surface but has never been grouped with the four terrestrials.
The four large outer worlds — Jupiter, Saturn, Uranus and Neptune — are sometimes called the Jovian or “Jupiter-like” planets because of their enormous size relative to the terrestrial planets. They’re also mostly made of gases like hydrogen, helium and ammonia rather than of rocky surfaces, although astronomers believe some or all of them may have solid cores.
Order of the planets by size (smallest to largest) If you were to order the planets by size from smallest to largest they would be Mercury, Mars, Venus, Earth, Neptune, Uranus, Saturn and Jupiter. Jupiter and Saturn are sometimes called the gas giants, whereas the more distant Uranus and Neptune have been nicknamed the ice giants.
This is because Uranus and Neptune have more atmospheric water and other ice-forming molecules, such as methane, hydrogen sulfide and phosphene, that crystallize into clouds in the planets’ frigid conditions, according to the Planetary Society (opens in new tab), For perspective, methane crystallizes at minus 296 Fahrenheit (minus 183 degrees Celsius), according to the U.S.
National Library of Medicine (opens in new tab),
How many universe do we have?
Arguments against the multiverse theory – Falsifiability There is no way for us to ever test theories of the multiverse. We will never see beyond the observable universe, so if there is no way to disprove the theories, should they even be given credence? Occam’s razor Sometimes, the simplest ideas are the best.
How many planets in the universe can support life?
How to calculate N – By covering the steps and events that led to Earth being able to support life, we can begin to estimate what N might be:
Average rate of star formation in our galaxy. There are roughly seven new stars formed in the Milky Way each year. Fraction of those stars that have planets.
When discussing the formation of planets, it is reasonable to assume that nearly all stars have planets orbiting them:
Average number of planets with potential to support life.
Here we could take our own Solar System as an example. 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.
Planets only exist for a finite length of time. You can assume that the average lifetime of a planet is 10 billion years.