The Earth is the third planet from the sun. It's a round sphere that's filled with magma and molten iron, and is around 4.5 billion years old.
As some of you might also know, this hasn't always been accepted. In fact, for some people, it still isn't accepted.
While for many of the following alternative Earth theories, most of you have probably heard of a few, but there might be a few that you haven't heard of.
So here now are the seven alternative Earth theories:
7. Hollow Earth
One of the oldest and most common alternative Earth theories, this theory is based on the belief that the Earth is hollow, and is actually only about a thousand miles thick (although the thickness varies). Another usual belief within the Hollow Earth theory is that the interior is also full of air and possibly life forms, maybe even intelligent life. It's also usually believed that at the exact center of the Earth is a small sun which provides both heat and light for the interior, and would explain the heat the scientist find from inside the Earth, and it's also believed that interior sun would also provide enough gravity for the surface, or that the mass of the Earth itself would be enough to produce one gee force worth of gravity.
This theory isn't even close to being possible.
If the Earth actually had a sun inside it, it would kill anything on the surface due to the huge amounts of radiation and heat it would produce, and a few hundred miles of dirt and rock would not be enough to shield the surface from the radiation that a planet would get from a star that's that close. Of course you wouldn't have to worry about radiation in the first place, because the gravity a sun can produce, even one small enough to fit inside a planet, would cause a planet to implode if one was inside a world. Even without the inner sun, the mass of the Earth would not be enough to produce the gravity that keeps us on the surface, and the centrifugal forces would throw everything that wasn't secured to bedrock off the surface.
6. Multi-Sphere Hollow Earth
In 1692, English scientist Edmond Halley proposed the idea that the Earth was not only hollow, but had several hollow spheres inside it as well, with one inside the next. Sometimes at the center is a small, solid planetoid, sometimes it's a small sun.
The problems with this theory is the same with the hollow Earth theory, but also the spheres would have to be rotating insync with each. If one sphere was either rotating even a little bit slower, or a little bit faster, the spheres would collide with each other, and destroy the planet.
5. Concave Earth
Probably one of the strangest alternative Earth theories ever made, basically the concave Earth theory is the belief that what we consider the surface of the Earth is actually the interior, and that all the stars, the sun, the planets, and the moon, are actually inside the Earth itself.
Besides the fact that the way centrifugal force works, in that the further away you get from the equator, the lighter the gravity would get, you would also be experiencing coriolis effect as well. Plus, you should be able to see the other side of the Earth with even a cheap telescope.
4. Flat Earth
(Note: this section has been edited to correctly state that the Flat Earth theory is a more modern belief, rather then an older belief)
Contrary to popular belief that this is a very old theory, the belief that the Earth is basically flat is a relatively modern theory, and in most interpretations is surrounded by a wall on ice, or that the water at the edge evaporates and returns to the Earth in the form of rain. Most believers in this theory also believe that the sun orbits the Earth, or that the Earth does orbit the sun, but in some strange zig-zag fashion.
Besides the fact that the pictures taken from outer space and the Moon obviously proves this to be false, if you get on top of a tall building or a mountain that has a lot of flat ground around you, you can see the curve of the Earth yourself. Also, if water was falling off the edge, evaporating, and turning into rain, then it would be raining on Earth all the time, and the Earth would be constantly covered in clouds.
3. Expanding Earth
This theory states that the Earth is actually expanding constantly, and that continents are really only moving away from each other because of this expansion.
The problem with theory is that it doesn't take into account certain things such as plate tectonics. Studies in plate tectonics clearly shows that the continents are moving either closer together, or further apart. In fact it's very well known that the Atlantic is growing, and the Pacific is shrinking. Also, if this was true, then why is 70% of the surface covered with water? There should be a lot less water covering the surface. And if the Earth is expanding, then how exactly is it getting filled in?
2. Geocentric Earth
Geocentric Earth is basically the theory that the Earth is either at the center of the solar system, or the center of the universe, and that everything else in the solar system or the universe orbits around the Earth.
This is one of the earliest and most famous theories to be proven false. Any one with a deceit telescope and enough patience can figure this out for themselves. In fact, Galileo Galilei's research about this is considered to be the birth of modern science.
1. Young Earth
What is probably the most believed alternative Earth theory today, the young Earth theory basically states that the Earth is only about 6,000 to 10,000 years old. While supporters of this belief usually accept every other scientifically proven fact about the Earth, the only thing they disagree with is the age.
This theory is based almost entirely on biblical beliefs, but modern day geology and certain scientific and geochronological techniques, such as radiometric dating, proves that the Earth is closer to 4.5 billion years old. Plus, there is really nothing in the bible that actually says how old the Earth is. Now of course there is the fact that the bible says God created Earth in six days, but many people, including old Earth creationists and Theistic evolutionists, often asks when it comes to that biblical belief, "Whats a day to God?"