How Astronomers Weigh the Universe (And Everything in It)
You’d be hard pressed to find a big enough scale, but it’s basically the same idea
By Charlie Wood
With a long enough lever and a place to stand, Archimedes knew he could move the Earth. Similarly, weighing massive objects like planets and stars on a balance scale as one might with a pound of salmon is conceivable only in theory, but a quick search of Wikipedia reveals a wealth of such unfathomable information: The eight planets in our solar system each weigh between 10²⁴ and 10²⁷ kilograms (that means a number from one to nine, dealer’s choice, with between 24 and 27 zeros after it). The sun hits 10³⁰. Our galaxy weighs in at around 10⁴² kilograms and the entire visible universe reaches something like 10⁵³.
You can try to convert those figures to something a little more familiar, such as the weight of a blue whale, by subtracting 5 from any of those exponents. But the numbers are unwaveringly huge no matter how you try to wrap your brain around them. Changing from kilograms to pounds doesn’t make much of an appreciable distance at these scales, either. When it comes to imagining such colossal masses, the human mind is completely out of its depth.
