The universe is so unfathomably huge that our tiny human brains can barely imagine just how big it really is out there. Case in point, a paper recently published in the Astrophysics Journal estimates that the mass of the Milky Way galaxy is 9.5 x 10^41 kilograms — 4.8 x 10^11 times the mass of the sun. That sounds wild, but can those impossibly gigantic numbers mean anything to us?
Let’s try to scale it up and make sense of this. I, a relatively average-sized guy, weigh about 160 pounds. A 12,000 pound (5.4 metric tons) elephant, the first object I came up with when I thought about heavy things, weighs 75 times as much as I do. The Revolving Service Structure (RSS) of launch pad 39B at NASA’s Kennedy Space Center is the heaviest thing people have ever directly weighed (says Guinness World Records), and at 2,423 metric tons, it weighs about 449 times as much as that elephant does.Now get ready, because here comes a number you’ve never heard of before (aside from in the headline of this post): The Milky Way weighs 392 decillion times as much as the heaviest thing we’ve measured on our planet. 392 decillion, or 3.92 × 10^35, looks like this: 392,000,000,000,000,000,000,000,000,000,000,000.
How did these astronomers arrive at this number? There’s some complex math involved, for sure, but in basic terms that definitely oversimplifies the process, they estimated its mass by observing its gravitational pull on globular clusters, which are cosmically large spheres of hundreds of thousands or millions of stars attracted to each other’s gravity and orbit galactic centers. We’ve previously used similar methods to estimate the mass of the sun, by observing its pull on Earth.
There, NOW do you get how big the Milky Way is?
Featured image: Luis Calçada
