The field of astronomy is no stranger to controversy, but when one astronomer declared it official in his opinion that the Earth is entirely unique in the universe, he said he came to the conclusion after studying 500 planets. The claim has brought up some interesting numbers that seem to indicate to the contrary.
To put it in shorthand there are some 200 billion stars in the Milky Way Galaxy according to conservative estimates. According to some astronomers this number could be as high as 400 billion. It’s not a small Galaxy, but it’s also not the largest in the known universe. Outside of the Milky Way there are other Galaxies and Galaxy clusters. Altogether there are 80 billion galaxies out there including some that are quite a bit larger than our own Milky Way Galaxy. Each of these stars has by conservative estimates around three observable planets orbiting it. Our own sun has eight, not including Pluto. Many of these planets have multiple moons – some of which are rumored to have liquid water. Earth has only one moon, but Jupiter has 63 confirmed.
Life on Earth as we know it is made up of Hydrogen, Oxygen, Carbon, Nitrogen, phosphorus, sulphur, and a few others. These elements have been distributed throughout the universe. There is also the need for liquid water. Water needs to be heated to just below 32 degrees Fahrenheit in order to go into a liquid state, and must therefore exist within what is known as the habitable or “Goldilocks” zone. Thus far this has been one of the difficulties in discovering whether or not planets can have liquid water on their surfaces. Gliese 581 d was discovered in 2009 orbiting in the Goldilocks zone as well as Gliese 581 g.
In 2010 scientists discovered evidence that life may have evolved quite differently from what we understand on our own planet suggesting it may have done the same elsewhere when in 2010 NASA scientists were able to use arsenic instead of potassium to form DNA strands in a microorganism suggesting that life as we know it is only a shadow of what life might develop from.
If each character on this page were to be converted to a zero, and you were to put any number one through nine in front of it, it would still not amount to a large enough number of suspected astronomical bodies in the universe. And each of them could have a crack or a crevice in which the proper elements have nestled and developed into a microorganism.
The only thing we know about life for sure is that one of those planets, Earth, definitely does have life on it. And with experiments going on each day that suggests life could exist far beyond what we currently think possible, the idea that after studying 500 planets we could consider ours a very exclusive club seems unlikely. Even Mars – our closest neighbor- is still being studied officially by NASA for signs that life could have existed there in the past and finding little to the contrary.