We live in a part of the solar system called the Goldilocks zone where it’s not too hot that all the water evaporates away, but it’s also not too cold where it freezes instead… and unless you’re an astronaut, the big spherical rock will be your home for life. But what if your home suddenly changed? What if, in split second, the Earth doubled in size?

Let’s assume the density remains constant, so the mass of the Earth increase as well. How would that change things? Well first off, gravity would be very different. The Earth would have eight times as much mass and gravity would be twice as strong, so if you stepped on a scale you certainly weigh twice as much as before. It would be much harder for you to walk and you get tired much more easily. After all, you’d feel like you were giving another version of yourself a piggyback ride all day, every day… which will look very funny.

Over the years, human bones, especially in the legs, would have to become stronger to support this increased weight, meanwhile trees would start to collapse and any new trees that grow in their place might not grow as tall. See, there’s a limit for how tall a tree could grow.

Usually around 400 feet(120m) or so. This limit is determined by gravity. Since the taller the tree is, the more energy is required to transport water from the roots to the top. If the amount of energy the tree gains from photosynthesis is more than the energy it takes to transport the water, it’ll keep growing otherwise it’ll stop. So if the Earth suddenly got twice as big, trees like the California redwood may not be as impressive.

Luckily, even though the gravitational pull of the Earth will be stronger, it still won’t be enough to break the moon apart. In order for that to happen, the moon would have to be within the Roche Limit. This is the minimum distance the moon can approach the Earth without being torn apart by tidal forces.

This happens because the near side of the moon is pulled in harder than the far side. When the moon get close enough to the Earth, the gravity holding it together is overcome by this cosmic tug. Inside that limit, Earth’s gravity will tear them apart giving us a ring like those around Saturn.

And the more Earth there is, the more it will heat up. If there are more unstable elements in the crust in interior, more heat will reach the surface and there may be much more volcanic activity — I don’t know about you, but I’d rather not live in a world where there’s a constant threat of an exploding volcano.

Anyway, if you can live anywhere in the universe, no limitations, where would it be and why? If I could, I’d totally live in Venus or even in Jupiter’s Great Red Spot…. It’d be pretty dangerous.