Eighty five years ago, on the 5th of October, 1923, a cosmic discovery was made from nearby Mt . Wilson Observatory. It was the finding of just a single star in a distant galaxy, but it was a sighting that would forever change the way we'd see our place in the universe.

For as long as man has looked up into the skies it had always appeared that we were at the center of all there was. It wasn't for some self-centered reasons that we came to that conclusion; it was because it really looks that way. We on earth feel no movement, but we see everything seemingly moving around us. We must, therefore, be at the center of a giant sphere of starry hosts.

That belief took a big hit in the 16th and 17th centuries when our worldview changed to one in which our planet, and all other planets and stars, orbit around something else - our sun. This was the great time of Copernicus, Kepler, and Galileo.

Time continues on, and with the invention and improvement of the telescope it was revealed that there are countless stars out there in all directions. Gradually, after decades of refining and reinterpreting our observations, it became the accepted view that our galaxy, our island universe, was all there was. We were a planet orbiting a star, and our star was a mere grain of sand in a giant starry sandbox.

And that was it. Beyond our sandbox was the void.

By the end of the 19th century, people started seeing things in their telescopes which were curiously like miniature versions of what we thought the entire Galaxy might look like. Were these spiral-shaped clouds - called nebulae - merely new stars being born, or were they distant galaxies like our own? If new stars, then our view of the galaxy remains safe. If distant galaxies, then a new paradigm shift awaits offstage ready for an entrance that will put a whole new plot twist in the Grand Scheme of Things.

You see, if they are distant galaxies then the universe is unimaginably bigger than anyone ever thought, and our galaxy would be just one of innumerable other galaxies. For some this would have deep philosophical implications.

If there was just some way to see more detail in those "nebulae" this problem would have an answer. As scopes were getting bigger, more detail could be seen, and some astronomers swore they saw stars in the swirls which would reckon them as distant galaxies, not local clouds.

It wasn't until Edwin Hubble came along that this debate was put to rest. Eighty-five years ago, using the 100-inch telescope at Mt Wilson, he photographed a minuscule pulsating star called a Cepheid variable in the Andromeda Nebula.

A Cepheid variable is a star that pulsates in brightness with great regularity. To make a long story short, knowing the pulse rate of a Cepheid can tell us how bright it should be. When we see how bright it appears to our eyes, and see how much it has dimmed with distance, we can use simple laws of physics to determine how far away it is.

Hubble used his calculations to show the world that the Andromeda nebula was nowhere within our galaxy, that it was at least a million light years away. It was no cloud, it was the Andromeda Galaxy.

Suddenly, overnight, the entire universe was seen to be immense, larger than anyone had ever dreamed, and strewn throughout not with just billions of local stars, but billions of other galaxies. We were a mere speck in a boundless landscape.
Not to despair! Although some now took the view that our new size relative to the new universe made us insignificant, that view has been changing over the last decades.

We now see that the universe must be the size it is, must be as dense as it is, must have as many stars and galaxies and voids as it does - no more, no less - for us to have life on this tiny little planet of ours. Why? Sorry, that is a discussion for another day.

Want to read a great book on the fascinating history of astronomy from Aristotle to modern day? Pick up Timothy Ferris' Coming of Age in the Milky Way.

Until next time, clear skies!