This picture of Betelgeuse is rather blurry. But that can be forgiven, since it’s 600 light years away. Or can it? How hard is it to see something that distant?

Consider measuring the moon by holding your hand out and squeezing your thumb and first finger like a caliper. It’s cloudy today, but I’d guess it would be slightly less than an inch from thumb to finger.

Betelgeuse is one of two stars marking the hunter’s shoulders in the constellation Orion, but it’s not practical to conduct this experiment. Which is why we have math. It’s about 600 light years away, and as wide as the orbit of Jupiter (light takes 80 minutes to cross from one side to the other.) Assuming the distance from your eye to your hand is one meter, you would need to hold your thumb and finger about a nanometer apart.

That distance is the length of ultraviolet light wave. But that picture was taken using infrared– with a thousand times the wavelength. That’s like painting fine art with a really wide paint roller.

[Sylvia was watching Jordan and me do these calculations last night. With luck she learned that math is fun and useful for grown-ups.]