can we create a new planet out of scratch

Whether it is a human activity or a meteor crashing into us. Planet Earth is not gonna last forever. Eventually the lump of space rock that we call home will one day no longer exist. What will we do as a species if this were to happen? The obvious plan is to reach out into universe and build colonies elsewhere but space travel is incredibly complex and we're still not sure if it's even possible to reach another solar system within a reasonable amount of time. But what if we build an entirely new planet ourselves.

We see artificial planet sized objects often quite often in science fiction. From the Death Star of Star Wars, the planets building facility and Hitchhiker's Guide to the galaxy and even far larger objects like a Dyson Sphere. The species shown being capable of building such creations are ofcourse increadibly advanced but What exactly would it take to actually build one?

At first it depends on what you mean by the question? Are you talking about a replica of planet like Earth? or A space station that's the size of a small moon or planet? The former would require a careful combination of elements and mass while the latter would still require enormous engineering feeds but maybe not quite as difficult. The most famous planet sized space statin fron sci-fi is the Death Star .

According to estimates at the construction of such a structure which is 74 miles in diameter compared to the Earth's 8,000 miles would require materials that weigh approximately 1 quadrillion tons which is about a millionth of the weight of Earth. Supplying all the material would be a mammoth task and impossible with current technologies. For example, on earth we produce about 1.5 billion tons of steel per year which means it will take more than 800,000 years to produce enough for a moon sized space station. Furthermore it would cost about 852 quadrillion dollars and that's not even taking into account how will we transport them to space? but let's say we could do all that once it's there the construction would actually be relatively easy. We can use robots to complete most of the work in the lack gravity in space means it wouldn't be too difficult to move all the materials into place. It would take a long time but eventually that would be possible.

Now the alternative will be to mine all the materials from an asteroids that are in space already. A number of companies are actually looking at the feasibility of doing this with some tests already being underway. If successful it could vastly reduce the cost of building things in outer space. This may also be a better plan because it's not even certain that steel would be strong enough .We may need to create artificial gravity which can be done by spinning the station and the force this would exert could crumple steel. So some researchers think a carbon-based material harvested from asteroids would be much better suited to the job.

Now despite the difficulties with building a moon sized structure, creating an actual planet is much bigger problem. Afterall, the Earth is already 4.5 billion years in the making. So how could we possibly replicate that? Well we wouldn't actually have to perfectly replicate the earth to get similar conditions. For example, gravity is related to mass so we could put the equivalent of one tenth of the earth's mass of rock into the space, the size of our moon to get the same reesult. There's aloy of rock and debris in space and our planet itself is formed by enough of it collecting together. So if we could develop technology that did this for us, we'd be off to a really good start.

Following thus, some have suggested we could build a fusion facility near the Sun which could produce some of the heavier elements that are needed. These dense metals could be layered on top of each other allowed to cool and then they would form a stable structure. The problem with this is that it would take tens of thousands of years to complete.

While building a planet completely fron scratch is so far beyond our capabilities. The idea of terraforming an already formed planet is far more within the realms of possibility. Nuclear detonations could be used on Mars to warm the planet's atmosphere and NASA has suggested that an artificial magnetic field could be created to deflect the solar winds in the same way that a naturally formed one would. It's thought that this type of structure would allow Mar's atmosphere to thicken which would warm it by about 7 degrees fahrenheit and in turn melt the polar ice which could contribute to a greenhouse effect and warm the planet further. According to researchers this could be possible within a few decades far sooner than creating an entire planet from scratch.

In conclusion, the idea of building a brand new planet sounds pretty excitinf but it is way beyond our current technologies. If we perfected the mining of asteroids and create robots that won't eventually turn on us, then it could be possible to build a large space station although this would be a monumental project to undertake. So basically it is far more realistic to look at our neighboring planets and to work out a way to adapt to their environment, to make them less hostile and this is going to be the most likely way that we'll be able to find somewhere other than earth to live.