As you may know, currently, scientists have data on the presence in the visible Universe more than 4000 planets. Some of these features are truly an incredible performance, being close to their bodies in elliptical orbits, or even revolving around several stars simultaneously. A fantasy Universe can seem endless, however, and it is sometimes limited by the rigid laws of physics. So, when it comes to the size of the planets, in particular their mass and radius, at some point we may face some notable limitations. In this case, how big can be the planet?
The biggest planet in the Universe
In the Solar system there are two types of planets: small, rocky planets of the inner part of our solar system is protected from external comet-asteroid assault gaseous outer planets such as Jupiter or Saturn. According to an article published on the portal theconversation.comscientists have long been arguing about the causes of a significant gap in size between the giant planets and rocky exoplanets, having formed a niche in the so-called super-earths with a radius from one half to two radii of our blue planet. However, as recognized by scientists, discovered supertall not so much in the Universe and their number is clearly insufficient to explain the new cosmic puzzle.
Researchers believe that the solution causes only a very small number of rocky exoplanets with a relatively large size, can be found in the atmospheres of these planets at the stage of their formation. So, after the birth of a new star in its vicinity is almost always a lot of extra material from gas and dust. Under the action of the gravity, the larger fragments begin to attract smaller objects, eventually forming young planetary system. As soon as new planets increase in size, its gravity grows, allowing exoplanet to capture not only the stones and the dust, but the gas that forms the atmosphere.
In that case, if the planet is relatively small with a radius of less than 1.5 times the radius of the Earth, its gravity is not strong enough to hold a huge number of atmosphere as on the planets. However, if the planet continues to grow, capturing more and more forming the gas atmosphere, the exoplanet is in danger of swell to the size of Neptune or Jupiter, whose radius is 4 and 11 times bigger than earth, respectively.
For this reason, the planet most often are either small and rocky or becoming a giant gaseous objects. To find a middle ground where they could be formed of a super-earth in this case is very difficult due to the fact that as soon as the planet will take sufficient mass and gravitational pull, it would require the presence of certain circumstances, which stops the accumulation of the atmospheric gas.
Another factor to consider is the fact that after the formation of the planet it doesn’t always stay on the same orbit. Sometimes the planets move or migrate to the star-master. At the moment when the planet approaches the star at a fairly close distance, its atmosphere is heated, causing the atoms and molecules move very quickly and avoid the gravitational pull of the planet. In other words, some of the small rocky planets are actually the cores of giant planets, gradually lost its atmosphere.