What exactly is gravity? Read on...
So what is gravity?
Simply put, gravity is the force that attracts everything together. It's what keeps you on earth, what helps you orbit the sun, what helps you stand up on the ground. But what exactly is gravity? Why is it there? Every force has a scientific explanation, but what is this one's, eh? Eh?! Fear not, for science boffins all over the world have taken a pop at this. Here is the answer:
Apart from having a few carbon atoms per square centimeter (wow, that's empty!), outer space is made from this 'fabric' made of spacetime. (We encountered spacetime in the dimensions and time travel page.) We can't directly access it, but it's there. Now, imagine that the sun was placed an the fabric. Of course, it'll create a dent in the fabric. If some planets trundled by, they might roll down the slope, and, because this fabric his no friction, even roll around a few million times. They would slowly get closer and closer to the sun until they get engulfed completely. (We are actually getting a few millimeters away from the sun per century, due the sun running out of hydrogen gas to burn.)
Despite being far up up, NASA ships feel pretty much the same gravity as we experience (roughly 90% of our gravity). This is because they are constantly falling, yet going across fast enough just to fall around the earths curve. Weird! However, you'll need to be traveling at 8 kilometers per second, otherwise you would be burnt up by friction with the air before you could enjoy the trip. On the moon, since it's smaller, you need to go much less faster. In fact, if you somehow landed on the moon, and shot a bullet at the horizon, prepare to wince in pain - you could be hit on the back by the same bullet. *BANG!* It has to be zooming at 1600 meters per second. This is the exact speed the German Paris gun fires.
A magnetic start
Before we start going into the boring details of what magnets are, imagine that the earth has the same gravitational pull, yet is hollow. "So what?" you might think. Well, because the earth's core is what creates the earths magnetic field (as they both include iron.), the earth won't have one. So down with the pigeons, who have magnetic crystals in their brain, as to detect the earths magnetic field. This is to help it find its way to its breed island. Also, we'll be open to the suns deadly radiation, since the field protects us from that. HELP!
So how do magnets work?
Well, when a magnetic field comes in contact with another, BOOM, they fuse. (If it's the north on south magnet or visa versa). So the real question is: where do magnetic fields come from? Well, electricity and magnetic fields are like a two-sided coin, they can turn into one or the other. Now, every magnetic object is full of electrons (electrons = electricity atoms), of which turn into the magnetic field. This can be explained with Einstein's theory of relativity. Imagine two train tracks next to each other, an inch apart, with one having a stream of protons (they are in the atom's nucleus [center] and have positive charge) down it and the other a stream of electrons (much smaller than protons, but with an equal and negative charge, orbiting the atom due to an electromagnetic, not gravitational force). Imagine that a test charge (positive for the sake of the test.) is sent through the middle. Now, the protons are going through the train track to the left, along with the charge, whilst the electrons of moving to the right. From the charges point of view, due to relative motion, the protons appear still as they are moving at the same speed as the charge. However, as your prospective get thinner as you approach the speed of light, whilst the proton's track look an inch part, the electrons looks thinner and closer, so the charge is drawn towards it. Aaand, that how magnets work.
Friction is where you rub your hands together to create static electricity or heat energy. It is what stops your feet sliding about when you take a walk. From slowing building tsunami waves to creating lightening from volcanic ash clouds due to rubbing particles, friction is everywhere. Ice has less friction, which is why you just keep slip-slidin' about on it. Normal ground has more friction, so you can walk comfortably. YAY! (Sorry, I meant "NO!" because it influences parents to take you on horrible walks.) This has huge influence on the world, much like gravity.
The atmosphere puts pressure on us and our blood, stopping our blood cells spreading out and boiling. If this happened, all our organs would swell up via the blood expansion. If we had a too heavy atmosphere, we'd implode. Too light? We'd explode. Yucky! Our atmosphere is roughly 5.5 quadrillion tonnes!
Did you know....?
If there was no air resistance, no matter how heavy two objects are, they'd hit the ground at the same time.