It wasn't all that long ago, just a few hundred years, that the stars overhead were still a beautiful mystery, woven into the religious beliefs and mythology of human civilizations — civilizations that could only look up and wonder what the sparkling night sky was trying to tell them. They used the stars to navigate, the moon to track the months and seasons, the constellations to tell stories, and held them up as proof that we are not alone in even the darkest of nights.
Although we know better now and recognize that every point of light we see is a distant star like our own sun — or possibly a far distant galaxy if our eyes are really good — the wonder has never really ceased.
If anything, the sense of wonder has multiplied as we try to comprehend our humble place in the almost infinite space that surrounds us, with its hundreds of billions stars in each of maybe half a trillion galaxies, where the light from even the closest star to earth, Proxima Centauri, takes 4.2 years to reach us at a speed we can scarcely comprehend.
The sheer scale of things defies imagination.
There are galaxies much, much larger than our own Milky Way, which is 100,000 light years in diameter — IC1011 is 60 times larger in fact.
There are galaxy clusters with quadrillions (thousands of billions) of stars. There's a vapour cloud that contains enough water to cover a trillion planets with earth-like quantities of the molecule. There are gas nebulas, remnants of exploding suns that are themselves 100 light years in diameter.
There are stars like VY Canis Majoris that are up to 2,200 times wider in diameter than our own sun — which is itself 110 times wider than Earth.
"In space travel," says Slartibartfast, a cantankerous character in the Douglas Adams' Hitchhiker's Guide to the Galaxy series, "all the numbers are awful."
And yet, with the right instruments and persistence, we can measure slight variations in the intensity of light from stars more than 1,000 light years away to discern whether they have any planets orbiting around them — how many, how big and in what kind of orbit. In fact, recent discoveries suggest that planets are theoretically possible around every star, and may actually be more common than we previously realized.
It goes without saying that the implications in the ongoing search for extraterrestrial life are enormous, as we burrow into data to reveal more earth-like planets that presumably have all the core precursors for life that are present everywhere — a list of ingredients that can be found scattered around the universe in huge quantities, from the surface of Mars to asteroids hurtling through space. It's important to know what the potential is, even if the distances are so huge that space travel between any two worlds is theoretically impossible for human beings.
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