How Does GPS Know Where You Are? ️ Owlo & Koko Explore Satellites | Kids Science Story

[00:00:00][music] How does GPS know where you are?

[00:00:05]>> Good afternoon, Koko. You look like you have a story bursting to get out today.

[00:00:11]>> Alo, guess what happened at the park yesterday? I used a treasure hunt app called Geocaching with my cousin.

[00:00:17]>> That sounds like a wonderful adventure.

[00:00:20]Did you manage to find the hidden treasure box in the end?

[00:00:24]>> We did. The app showed a little arrow pointing exactly where to walk and it never got confused even near the trees.

[00:00:32]>> That little arrow uses something called GPS which stands for global positioning system. It is one of the cleverest tools people have ever built.

[00:00:43]>> But how does GPS actually know exactly where I am standing even when I keep moving around a huge park?

[00:00:52]>> Great question. High above us, there are more than 20 satellites circling the Earth. And each one sends out a special signal.

[00:01:01]>> Wait, satellites? You mean those things that look like tiny stars, but are actually machines floating way up in space?

[00:01:08]>> Exactly. Right. Your phone listens for signals from at least four of those satellites all at the same time.

[00:01:16]>> Four signals sound like a lot to keep track of. What do they even tell your phone?

[00:01:21]Each signal carries the exact moment it was sent and your phone calculates how long that signal took to arrive.

[00:01:30]>> So the phone is basically doing math with time to figure out how far away things are. That is kind of amazing.

[00:01:38]>> It really is. Signals travel at the speed of light. So even a tiny fraction of a second tells your phone the distance to each satellite.

[00:01:49]>> Okay. But knowing the distance from just one satellite still doesn't tell you exactly where you are, right?

[00:01:56]>> You are thinking like a true scientist, Koko. That is exactly why we need more than one satellite. Let's go try this out in the gym.

[00:02:07]>> This looks fun already. What are we doing with these three long ropes on the floor?

[00:02:12]>> Each rope stands for the distance from a different satellite. I will hold one end and you find the spot where all three ropes reach their full length at once.

[00:02:23]>> Okay, let me try. If I stand here, this rope is too short and that one over there is too long.

[00:02:29]>> Keep adjusting your spot. Once every rope reaches its limit at exactly the same time, you have found your one true location.

[00:02:39]>> I found it. This is the only place where all three ropes fit perfectly. It's like they are agreeing on one exact spot.

[00:02:47]>> That is exactly how GPS works, except with radio signals instead of ropes and satellites instead of us holding the ends.

[00:02:58]>> So, what was that fourth satellite you mentioned earlier? What job does that one do?

[00:03:03]>> Great memory. The fourth signal helps fix tiny timing mistakes since your phone's clock is not nearly as precise as the atomic clocks riding on the satellites.

[00:03:15]>> Atomic clocks? That sounds like something straight out of a science fiction movie.

[00:03:20]>> They are very real and incredibly precise. Some can lose less than 1 second every 100 million years.

[00:03:30]>> Whoa, wait. Does GPS ever stop working?

[00:03:33]Like when I was under all those thick trees at the park.

[00:03:37]>> Good observation. GPS signals are actually quite weak. So thick trees, tall buildings, or being indoors can block them before they reach your phone.

[00:03:48]>> That explains why the arrow on the app got a little wobbly near that big oak tree yesterday.

[00:03:54]>> Exactly. The satellites need a clear path through the sky to send their signal all the way down to you.

[00:04:03]This is so much cooler than I thought. I just figured GPS was some kind of magic hiding inside my cousin's phone.

[00:04:11]>> It certainly feels like magic, but it is really clever science using space, time, and a bit of math working together. Now, why don't you tell me what you learned today?

[00:04:23]Okay, so GPS uses satellites way up in space that send out signals telling my phone exactly what time it is, and my phone does math to figure out how far away each one is. Kind of like our rope trick in the gym.

[00:04:37]>> That is a perfect summary, Koko. You explained it even better than some of the science books I have read.

[00:04:43]>> And I learned that trees and buildings can block the signal, which is why my map went wobbly under that giant oak tree. Maybe next time we can find out how satellites stay up in space without ever falling down.

[00:04:57]>> I would love that, Koko. That sounds like a wonderful question for our very next adventure together. If you had fun today, ask a grownup to get the free Ask Alo app for more stories. And don't forget to subscribe so we can make even