Earth's moon is moving away from our planet, travelling further away from Earth at a rate of about 3.8 cm per year!! Ain't that cool!! =D
How to proof it, any evidence?
Lunar Laser Ranging Experiment (LLRE) -
Back in the days of Apollo moon missions, astronauts have placed laser reflectors on the moon and scientist have since shot laser beams at the reflector from Earth to calculate the actual distance.
After years of bouncing laser beams off it, they can conclude it's moving further away each year. The use of laser beams to measure distance between Earth and Moon is said to have an accuracy of up to 5cm (centimeters), as stated on NASA website.
In the 35 years since the first LLRE reflector was deployed by the Apollo 11 astronauts its still being used today!! Lol just place a mirror to reflect light beams? Intelligent! It should be so easy to maintain, not to mention it really doesn't cost too much! Wooohooo!!!! ($_$)
Earth - Moon Relationship:
So then why does the Moon want to move away from us?? Perhaps the Moon decided she doesn't really like Earth, after all they've been together for 4.6 billion years, now that's commitment. =P
Okay, if Moon didn't like Earth and wishes to leave, why did it take her so long to figure that out?
Here's why - it didn't. Moon started to move away from earth at a pretty constant pace after its formation. Moon was much closer to earth billions of years ago, as a matter of fact, about a billion years ago, the Moon was so much closer to Earth then it is today that it needed only 20 days complete an orbit (around earth)! That means the maximum number of days you're going to get in a lunar month is erm ... 2o!! Yes, just 20, hmmmm ... suddenly February seems awfully long lol. Shorter days, shorter months, shorter years.. by that standard we'll all get to live till a much older age.. possibly 100? =D
Why is moon still moving away?
Well, blame it on the titans! ... Sorry, I meant the tides... you know, those from the ocean. =P
And remember that interesting force we've all heard of? - Gravity.
Earth being the bigger planet exerts it's enormous amount of gravitational force on the smaller moon, pulling it, affecting its orbit. While the moon also uses its gravity to affect Earth, it just wasn't strong enough to affect Earth so dramatically. However subtle effect have been noticed and one of the most noticeable, is raised ocean tides.
The side of Earth that faces the Moon experienced a much stronger gravitational pull as compared to other parts of the Earth simply because its ... well, closest to the Moon. Gravitational pull of the Moon continues to tugs on the surface of the ocean water, drawing more water towards it, this resulted in a bulge of water in the ocean facing the Moon - that is how we get high tides. As Earth rotates that bulge effectively moves around our planet to produce high and low tides all over the world. This effect also stretches the Earth a little, making the shape of our planet slightly oblong. The parts that "stick out" is known as tidal bulges.
Now, this explain how tides are formed, so how about the part of why Moon is moving away from Earth?? Well.. 2 things to note, 1st - Earth's rotating speed on it's axis, 2nd - the speed at which Moon orbits around Earth.
And here it goes .. Earth rotates faster on its axis taking just 24 hours to complete a cycle. The speed at which Moon takes to complete 1 orbit AROUND Earth is 27.3 Earth days. As Earth rotates, the tidal bulges tries to "speed up" the Moon, its gravitational force tugging it ahead in its orbit. At the same time, the Moon's gravity is also pulling back on the tidal bulge of the Earth, slowing Earth's rotation by approximately 2 milliseconds per 100 years. So yes.. if you lived to at least a 100 years old, perhaps you can tell you grandchildren that when you were young, your day was 2 milliseconds shorter ... not that they'll care, oh well. =P
Anyway... still remember the tidal bulges that tries to "speeds up" the Moon's orbit by tugging it slightly ahead? Well, how it get "slightly ahead" is because those tidal bulges aren't EXACTLY at the nearest and farthest points but rather dragged slightly beyond them by friction as Earth rotates. This pulls the moon slightly forward in its orbit, giving it more energy, elongating its orbital path and so the poor Moon now has to travel an even greater distance to complete 1 orbit round the Earth. Oh~ by the way, the "further distance" translates to just +3.8cm each year.
To sum it up:
- Moon slows Earth down by approximately 2mm every 100 years while,
- Earth increases Moon's orbit path by 3.8cm per year.
Clearly, in the game of gravitational force, size matters. =D
