Shaun Johnston

Whenever I travel to the central business district of Brisbane, I am struck by the scale of the concrete and glass skyscrapers dominating the skyline. I know these are by no means impressive buildings on a world scale, but still, they look pretty intimidating when you’re standing at the foot of one.

Given the relative awe that hits me when seeing a structure of this scale, I decided to compare it to, say, celestial scales. With a little research, I found some figures and away I went.

Let’s say we take a 180 metre skyscraper. That is about 100 times the height of the average male human. Pretty impressive. Now think about the diameter of earth - 12,750 kilometres, or 70,833 of those skyscrapers stacked on top of each other. That is almost impossible to imagine. Unfortunately for the human brain, that’s just the beginning.

Jupiter, the largest planet in our solar system, is 142,800 kilometers in diameter. This is equivalent to about 11 Earths laid end to end. 779,163 skyscrapers.

Sol, our sun, is 1,390,000 kilometers in diameter. Equivalent to just under 10 Jupiters, 110 Earths or 7,791,630 skyscrapers. Consider that the distance to our Moon is 382,500 kilometers. This means Sol, by itself, has a diameter of over three times the distance from Earth to the Moon.

But Sol is just a runt in the grand scheme of things when it comes to stars.

Sol is a yellow dwarf, one of the most common star types in our galaxy. They’re small, long-lived and quite stable as a rule, which is likely why life has arisen here. The larger stars get, the lower their lifespan. Sol will likely last another 5 billion years or so, while some of the largest giant stars may live for a few tens of millions of years. These stars are unimaginable in scale, so much so that if our Sol were laid next to one, it would barely be visible.

The largest known Red Giant star in our galaxy, Antares, has a diameter approximately 700 times that of Sol, or around 973,000,000 kilometers. Consider this. What if, somehow, Antares replaced our Sol in our solar system? Well, that would mean that Mercury, Venus, Earth and Mars would instantly be swallowed whole, because the radius of Antares is larger than the orbiting distance of these planets around our sun. Jupiter, orbiting at a distance of approximately 780,000,000 kilometers, would most likely survive, as would the other gas giants, at least long enough for Antares’ massive gravity well to suck them in and swallow them as if they never existed.

But there’s more. VY Canis Majoris is the largest known star in our galaxy - a Red Hypergiant with a diameter of approximately 1800 to 2100 that of our sun - or between 2,502,000,000 and 2,919,000,000 kilometers. This is close to the orbiting distance of our second largest gas giant, Saturn. Also, at this point we’re looking at 16,216,667,000 skyscrapers (yes, sixteen billion). I literally cannot imagine something of this magnitude, and I expect that if I did see it from a relatively safe distance, my mind would be overwhelmed anyway.

These are just the Suns. We haven’t hit the size of our galaxy, the Milky Way, our Galaxy Cluster or the possible size of the Observable Universe itself, and there is really no point because it is unimaginable anyway. No wonder people look to gods when faced with the unbelievable size and majesty of our Universe.

Further Reading:

I have always had an interest in the cosmos and its magnitude but I just can’t imagine the scale. So, in a quest for enlightenment I happened across some images kindly drawn up by folks who want to help people make that correlation. Comparative planetary and stellar sizes