If I look at Sirius in the night sky, how many photons from that star are hitting my eyeballs per second?

Question

If I look at Sirius in the night sky, how many photons from that star are hitting my eyeballs per second?

In: Physics

Answer 1

Alright! Let’s imagine you’re looking up at the twinkling stars in the sky, and one of those stars is Sirius. Now, Sirius is really far away, much farther than you can imagine. When you look at Sirius, you can’t see it just like you see things up close because it’s so, so far away.

But, let’s talk about these tiny things called photons. They’re like little packets of light that travel super fast. Now, imagine these tiny photons coming all the way from Sirius to your eyes. They’re moving really quickly!

So, to answer your question: even though Sirius is very far away, there are lots and lots of these little photons zipping through space from Sirius towards your eyes every second. It’s like a big stream of these tiny bits of light traveling all that distance just so you can see the star shining in the sky.

Now, exactly how many of these photons are hitting your eyeballs every second? Scientists have figured out that it’s about 4 × 10^14 (that’s a really big number!) photons per second from Sirius hitting your eyes. That’s a whole bunch of little light packets making their way to you from way out there in the night sky!