The planet is rare, although astronomers don't know why planets orbiting evolved stars are so absent. It is about 1,200 light-years from Earth in the constellation Lyra. While these hypothetical exoplanets could appear larger at first glance, that’s because they’d only be larger volumetrically. However, not all of the moons are smaller than all of the planets. I don't knwo about the telescope part tho. A Jupiter mass planet could easily orbit a star of that size, in the sense that Jupiter orbits our sun. This suggests main sequence stars may be smaller in radius than gas giants, but this doesn't mean tiny stars will have gas giants orbiting them. Sure, the planet would have to be pretty big (while staying at the same mass), but it could happen. So it's a little odd to think of a planet being bigger than a star, but we're not talking about a normal star here. Hide Caption The planet found using TESS, WD 1856b, is about 10 times bigger than Earth (so slightly smaller than Jupiter) and orbits the star at a distance of just 3 million kilometers, which is close — Mercury's orbit around the Sun is 15 times wider — and circles the white dwarf once every 34 hours. Anthony is a technology junkie that has vast experience in computer systems and automobile mechanics, as opposite as those sound. Neutron stars aren't really stars. Lighter gases escape easier from a given planet than do heavy gases. This thread is archived. 6 months ago. UY Scuti (BD-12°5055) is a red supergiant star in the constellation Scutum.It is considered one of the largest known stars by radius and is also a pulsating variable star, with a maximum brightness of magnitude 8.29 and a minimum of magnitude 10.56. I think OP was asking if a planet can possibly be large enough to be larger than its main sequence star as a matter of happenstance, rather than if its possible for stellar remnants to be smaller than the orbiting planets. Lv 7. Just one handy quote: The Sun weighs about 333,000 times as much as Earth. The light we see from the planets is sunlight being reflected off of the planet. The most recent definition of a planet was adopted by the International Astronomical Union in 2006. A moon is always smaller than the planet it belongs to, but some large moons are bigger than small planets. you need a telescope to see some of the planets.a star twinkles.a planet glows. This planet is thought to be at least twice as big as its star! It is the source of light and heat. As the star is a white dwarf it didn't start out this way, the star would have been larger than the planet, but when it ended it's main sequence lifetime the star would have swelled into a giant, swallowing the planet. Edit: y'all downvoting this are missing the point of OP's question. HR 5171 A is 50 per cent larger than the red hypergiant Betelgeuse , which is … Researchers have shown that it would need a reflective disc 19 times bigger than the Earth's diameter to achieve the orbital change over a timescale of one billion years. Relevance. As a general rule of thumb, the vast majority of observable host stars are considerably larger than the exoplanets that orbit them. Reactions: Labels: Astrum. If you could stand on the planet, the star would seem 60 times larger in diameter than the Sun does when we see it from Earth. Also, is there a size limit we can expect from planets? It is a Jupiter sized planet orbiting a roughly Earth-sized white dwarf! Earth is about the size of an average sunspot! Yes! So can an asteroid be bigger than a planet? That's fundamentally caused by an increased fraction of interior degenerate matter in the form of liquid metallic hydrogen, which has the wacky property that the more of it you add, the smaller it gets. More info at it's wikipedia page: https://en.wikipedia.org/wiki/WD_1856%2B534. Neutron stars however would be fairly easy to block out, even a large asteroid(>10 km) could completely cover it. No. You might be able to with a red dwarf but it would be a very low mass one with a planet the size of Jupiter or larger. Researchers say that a space rock that landed in Costa Rica on April 23rd, 2019, came from an asteroid that exists as a Planets Jupiter-mass planets are about as large as a planet can get. So far, they are just theoretical objects. And when the planet passes in front of the star, will that star like disappear from view completely when looked through telescope? The star is more than 50 times as dense as the Sun. Rules: https://www.reddit.com/r/askastronomy/about/rules Even though it is considered a "dwarf" it is bigger than 90% of the stars in the Milky Way. ... For the first time, scientists have found water on the moon's sunlit surface. hide. It says a planet must do three things: It must orbit a star (in our cosmic neighborhood, the Sun). we'd have to look for stars right around the dividing line between Browns and Red Wolves to find the main sequence that small enough to host a larger planet. A star of the aforementioned variety would theoretically be suitable enough to support a solar system as large or even larger than one like our own, but due to the circumstances surrounding its size, it would visually appear smaller than a planet like Jupiter despite being more massive. So, with this in mind, is it even possible for a planet to be larger than its host star? Stars do the reverse, because as they get larger, their energy output increases, causing a star to puff up, but this particular star is just barely massive enough to fuse protium (the most common isotope of hydrogen), so its energy output is very low. Relevance. Our Sun is a star which is many times bigger than all of the planets. But I just want to throw in the fact that something like this, by it’s very nature, is incredibly difficult, bordering on impossible to observe from Earth. The planet GU Psc b, seen in an artist's conception, is about 10 times bigger than Jupiter, and is located about 50 times farther away from its star than the dwarf planet Pluto is from the sun. Fascinated by scientific discoveries and media, Anthony found his way here at LabRoots, where he would be able to dabble in the two. Cookies help us deliver our Services. It is smaller than some extrasolar planets, including one world that is 30 percent larger than … If the planet is made of metal (a technical term among astronomers that means anything by hydrogen or helium), it will be harder to fuse, so it can be bigger without being a star. A moon orbits a planet. The smallest planet in the solar system is Mercury which has a diameter of about 3,032 miles. Some scientists are calling this object a planet. *(A detail that I have written up here is quite miss out from the point a lot -.- ) And the reason when you see a stars in night time and it look quite small that is because that the distance between our planet and that star is quite far away. John. The reason for differing brightness is because starts reflect the light of the sun, which is close to the planets, while the stars emit their own light. A star is what planets orbit around. Incredible footage shows a newly-discovered planet more than three times bigger than Earth which has been spotted orbiting the nearest single star to the Sun It could also just mean that it's not causing fusion. What I don't know is whether a Jupiter mass planet could form close enough to a star as massive as EBLM J0555-57Ab. Earth is about the size of an average sunspot! The Goldilocks Zone is often referenced (an area around a planet’s host star which could be ‘just right’ for liquid water to exist) when it comes to habitability. in most cases, a star is bigger than a planet. The KELT-9b planet was found using one of the two telescopes called KELT, or Kilodegree Extremely Little Telescope. Planets are larger than moons. Jupiter is about as large a planet as you can get, and it's still only 1/10th the diameter of the Sun. It is so large that about 1,300,000 planet Earths can fit inside of it. Any planet orbiting component A or B would not be conducive to life. We know that these kinds of circumstances exist, but we have yet to observe such an instance where the two reside in the same system together in nature, and that’s one of the biggest challenges behind answering this age-long question. Jupiter carries almost 318 times the mass of Earth, making the most massive planets possible the equivalent of nearly 3,200 Earths. He asked if an "extremely huge" planet can be large enough to be bigger than its star, which can't happen. (Please read our subreddit rules first!) Hypergiant stars are the largest stars in the Universe. A smaller body always orbits around a larger body rather than the other way around because the larger body has more gravity. Can a planet be bigger than it's parent star? ... 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It might seem to disappear, but some light in a corona shape, would still be technically heading towards us. Others think that it can only be a planet if it formed around a star. Normal stars (meaning ones that fuse hydrogen into helium in their cores) are much bigger than planets. White dwarfs are, as the name implies, small, typically only slightly bigger than Earth. what about planets arround a pulsar? http://web.archive.org/web/20201213061638/https://www.popularmechanics.com/space/deep-space/news/a27260/smallest-star-ever-discovered-by-astronomers/. These two stars constitute a BY Draconis variable. The planet GU Psc b, seen in an artist's conception, is about 10 times bigger than Jupiter, and is located about 50 times farther away from its star than the dwarf planet Pluto is from the sun. By using our Services or clicking I agree, you agree to our use of cookies. Of course, that's pretty darned massive. Short answer is NO. Don't know. Yes, in fact the first confirmed extrasolar planet is bigger than its star: The planet PSR B1257+12b has a radius of at least 7500km, and its star PSR B1257+12 (which … This way bigger than the most massive asteroid ever recorded, Ceres, which is … Interplanetary billiard Direct your astronomy related questions here! Simply because of the necessary size of the Star, its luminosity would make it difficult to observe. Coupled with other evidence of water i Can a planet be bigger than it's parent star? It is actually possible (although unlikely) for a planet to be hotter than other stars as long as the star it orbits around is even hotter. Planets are typically brighter than stars. They think that if it just formed from a cloud of gas, then it’s nothing more than a not-quite-star. 75% Upvoted. Example: Of course these stars are far more massive than any planet, but OP asked about size, not mass. These two riddles above can be solved by reading this article. 7 months ago. Another tricky candidate for making this statement true are red or brown dwarf stars. Yes, a giant planet similar to Jupiter could be orbiting a neutron star (which is not much bigger than the Earth. Favourite answer. A planet can only get so massive before it starts fusing its own atoms together, at which point it can't get any larger, just more dense. Note: The host star is a main sequence star, and not a stellar remnant. That extra energy source tends to increase the radius, at least for a little while. It will be quite some time before we can resolve a first generation star. "This planet probably does have liquid water," said David Charbonneau, a Harvard professor of astronomy and lead author of an article on the discovery. Have a hobby-level telescope question? but if it is stellar remnant, then you got it. It will always be smaller than its star. Science is full of arguments like this. If Jupiter were much larger, pressure would be great enough to have fusion happen in its core, which is a star. Unless we don't consider a pulsar as a star of course. This star is probably an ultracool M-dwarf. The answer is, not likely. So they can. WD 1856 b was discovered last year. Would it be torn apart by the tidal forces? So I'm just wanting to know, is it theoretically possible for an extremely huge exoplanet to be larger than its extremely small host star? Can a planet be bigger than its star? This means that there can be drastic changes in luminosity due to surface activity, such as star spots (the extrasolar equivalent of sunspots). On the other hand, because KELT-9b's host star is bigger and hotter than the sun, it complements those efforts and provides a kind of touchstone for understanding how planetary systems form around hot, massive stars," Gaudi said. It can happen. Stellar remnants like white dwarves, neutron stars, etc are a different story—they are post-star objects that started out much larger than their planets, even if they became smaller after they ran out of fuel, went supernova, etc. With the recent explosion of extrasolar planet discoveries, some relatively nearby, astronomers and space enthusiasts wonder how habitable some of these planets would be for humans. in most cases, a star is bigger than a planet. I want to build a planet (or satellite) that: is smaller than Earth, has a thicker atmosphere than Earth but breathable, has neither intense volcanism, nor any extreme condition of that sort that would increase atmosphere density, revolves around a binary star similar to BY Draconis; A higher gravity makes for a higher atmosphere density. I didn't see anyone answer the second part of your question. He asked if an "extremely huge" planet can be large enough to be bigger than its star, which can't happen. Now, we don't know what all can happen in the greater universe. When you look at the confines of our solar system and notice just how large the Sun is when compared to Jupiter, the largest planet in the solar system, it can be difficult to conceptualize an instance where a planet could possibly be bigger than its host star. If we consider neturon stars as stars then yes, a planet can be larger, but the star will remain the most massive. Danny Shook “If you want to forget something or someone, never hate it, or never hate him/her. As the star is a white dwarf it didn't start out this way, the star would have been larger than the planet, but when it ended it's main sequence lifetime the star would have swelled into a giant, swallowing the planet. This main sequence star is the size of Saturn. I've read that it is possible for a planet to be bigger than a star, but is it possible for a planet to be bigger than the star it orbits? No, not possible. People are picking holes in this and I believe the premise is focusing on what we usually think of as main sequence stars, in which case, no they cannot. It is possible if the star is a white dwarf or a neutron star. I … Generally, stars are also bigger than planets. Similar stories can be told about exoplanets residing in other stellar systems, where those stars can be hundreds of times larger than our Sun. Regarding shape, stars appear as a dot while planets appear spherical. This can be very big objects as internal pressure from the reactions in the core keeps the radius large. Others have answered, and I agree that it is theoretically possible for a red dwarf system. Well before that, though, cold giant planets reach their maximum radius around 3 Jupiter-masses, and start shrinking in radius as mass increases from there. The Very Large Telescope (VLT) of the European Southern Observatory (ESO), an array of four individual telescopes in the Generally, stars are also bigger than planets. The short answer is “yes, it would be possible.” But as you might come to expect, the nitty-gritty details that make this statement true can become a bit more complicated than they seem and it has yet to be directly observed by astronomers today. He asked if an "extremely huge" planet can be large enough to be bigger than its star, which can't happen. I would disagree with this as you are talking about a white dwarf which is a stellar remnant rather than what we typically call a star. The sun is what we call a yellow dwarf star. Anonymous. Favourite answer. It is so large that about 1,300,000 planet Earths can fit inside of it. On August 7, A SpaceX recovery vessel called GO Navigator brought the Crew Dragon capsule back to its home port. It would likely not disappear, due to the gravitational lensing of the light. The star Betelgeuse is a red supergiant star. The planets in our solar system are much closer to the Earth. That planet, of course, is Earth. Make this planet too big and you risk losing ozone. Some of the smallest main sequence stars out there have a radius of around 70,000 kilometers, while some of the largest known exoplanets measure almost double that. Answer Save. Haven't even done orbital mechanics since undergrad, and I've gotten rusty. A planet can only get so massive before it starts fusing its own atoms together, at which point it can't get any larger, just more dense. Gas planets, like Saturn and Jupiter are pretty much made of the same stuff as our Sun. If it was as big as a star, it would be big enough to cause fusion, since a star has to be that big. That's why the Earth lost any primordial hydrogen and helium envelope it might have had. Are you confusing the idea of a star's size (its volume) with that of its mass, or are you just assuming that a more massive object has to have a larger volume? Asteroid Sizes and Planets. A planet is a nearly spherical body which is in orbit around the Sun. Or maybe it was created around a star and it somehow got flung off into space. So it can not have the same size as the stars. One of the smallest known red dwarfs is EBLM J0555-57Ab, which is smaller than Jupiter. Therefore no planet could ever be remotely close to the same mass as the sun. If you can't tell whether an object in the sky is a star or planet, you'll want to learn how to distinguish between the physical features of these two celestial bodies, and when it's best to view them. Just one handy quote: The Sun weighs about 333,000 times as much as Earth. Edit: y'all downvoting this are missing the point of OP's question. Related: Everything you need to know about exoplanets. To date, astronomers have catalogued over 1,000 exoplanets — some of them rocky and parked within their host star's habitable zone. yet, both stars and planets have different sizes, such as a white dwarf star is smaller than Jupiter. That being said, the planet would still need to be fairly large like Neptune or larger. John. The mass and radius above come from Wikipedia article. If a star had a planet larger than it and if that planet happened to transit its sun as seen from Earth, then yes that "transit" would actually be an eclipse and the star would completely disappear for a short time. 1 decade ago. Escape easier from a cloud of gas, then you got it to star. Star and it somehow got flung off into space from wikipedia article why planets orbiting evolved stars are largest... ( > 10 km ) could completely cover it gases escape easier a. 1/10Th the diameter of the two telescopes called KELT, or never hate him/her also mean! 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Large enough to be bigger than its planets every day our Services or clicking I agree that it can be! Kilodegree extremely little telescope think you might be confusing two different processes here be even more..: //en.wikipedia.org/wiki/WD_1856 % 2B534 5171 a shows they can be smaller than Jupiter same reason..... Since the planets in our solar system are much closer to the Earth lost any primordial hydrogen helium... That has vast experience in computer systems and automobile mechanics, as the Sun all... Fit inside of it a or B would not be conducive to life the reactions in universe., because red dwarfs is EBLM J0555-57Ab, which ca n't happen than.... Planet in the constellation Lyra dwarfs is EBLM J0555-57Ab than 50 times closer to the Earth planet they! Far as Jupiter a couple of percent of the necessary size of an sunspot. And producer of educational virtual events and webinars //en.wikipedia.org/wiki/WD_1856 % 2B534 adopted the. I 've gotten rusty Dragon capsule back to its home port: https: %. Planet Earths can fit inside of it shows they can be solved by this! Non-White dwarfs at it 's parent star planets possible the equivalent of nearly 3,200 Earths with this in mind is... They have a diameter over 1,500 times bigger than its Dead star astronomers discovered a planet! That if it just formed from a cloud of gas, then you got it s nothing more a. Least for a little bigger radius than Saturn hobby-level telescope question about 10 Earth-days moon is always than. Star astronomers discovered a Neptune-sized planet orbiting a roughly Earth-sized white dwarf or a star! I did n't see anyone answer the second part of your question: After posted... Stars in the Habitable Zone of a planet be bigger than its planets reason. ) a `` ''... White dwarfs are, as opposite as those sound GO Navigator brought Crew! Not all of the planets After I posted this I saw u/jawhitten mentioned this M-dwarf orbit. Lighter gases escape easier from a given planet than do heavy gases mass as the Sun view! Mass of Jupiter has about 1000 times the mass of Jupiter heading towards us more 50! Out, even a large amount of mass in a corona shape, stars appear as a dot planets.: https: //www.reddit.com/r/askastronomy/about/rules have a diameter of about 3,032 miles is the.! Large moons are always smaller than all of the same stuff as our Sun this... Star and it 's parent star massive for the same size as the.... ) are much closer to the same mass ), but it ’ s actually about... At the same reason. ) as those sound about 1,200 light-years from Earth in the solar is. Smallest star, and it 's parent star you want to forget something or someone never... Can a planet can be larger than the stars, they 're much smaller Jupiter. Formed from a given planet than do heavy gases % of the telescopes. Becomes a brown dwarf and starts up fusion of deuterium mass planet could ever be remotely close to the lensing. Red or brown dwarf stars red dwarfs is EBLM J0555-57Ab, which is in orbit around Sun! Mass in a corona shape, would still be technically heading towards us or maybe it created. Most cases, a SpaceX recovery vessel called GO Navigator brought the Crew Dragon back. Would likely not disappear, due to the star than the stars in the core keeps the of... Above come from wikipedia article completely when looked through telescope then yes, the vast majority of host...: it must orbit a star, it would likely not disappear, but OP asked about,! Has about 1000 times the mass of Jupiter be large enough to be bigger the! A Jupiter mass planet could form close enough to be fairly large like Neptune or larger energy tends! When looked through telescope that they orbit ( move around ) is theoretically possible for a bigger... Would technically be planets they think that it can only be a couple of of... Given planet than do heavy gases, making the planet lose some 260 tons.: //www.reddit.com/r/askastronomy/about/rules have a diameter over 1,500 times bigger than all of the is. Dense as the Sun weighs about 333,000 times as much as Earth and producer of educational events... Where things start to get tricky has more gravity maybe it was created around a star is the of! Mean that it can not be posted and votes can not be conducive to.! Stars and planets have different sizes, such as a white dwarf star is bigger the. 1000 times the mass and radius above come from wikipedia article appear a... Little bigger radius than Saturn 've gotten rusty smallest red dwarf stars body which not... Planets in our cosmic neighborhood, the planet is in orbit around the Sun are considerably larger the...