When you look up at the night sky, you’re seeing the long-ago light from distant stars. But how can you know how far away they really are? You can’t exactly roll out a measuring tape. Luckily, there’s ...

If you want to find the size of a basketball, you can use a normal meter stick to measure the diameter. You should get a value of around 0.24 meters. Please don't use inches—they are just harder to ...