Pssst! You! Yeah, you... are a passenger on a planet... on a blue-green planet that's orbiting a golden star. And right now we are traveling through the part of our yearly orbit where many of the birds in our northern hemisphere are migrating to warmer homes. Long distance migrants travel 200 to 400 miles a day, and 90 per cent of migrating birds fly at airspeeds between 15 and 45 miles per hour. But how do they find their way? Many kinds of birds - and we don't yet know how many - navigate by the stars.

Imagine our Earth looking like an olive with a toothpick in it. Just as the olive can spin around its toothpick, our Earth spins around its axis. Now imagine this Earth-olive surrounded by billions of stars. Some stars are shining on Earth's northern hemisphere, and some are shining on its southern hemisphere. But one star - and one only - is shining directly onto the top of the toothpick, directly onto our planet's north pole. This is the North Star - also known as the Pole Star and as Polaris. If you're looking for it, you'll want to know that it's not the brightest star in our sky. It's the 57th brightest.

If you're standing at the North Pole, Earth's axis comes straight up through your feet, legs, spine and out the top of your head. So the North Star - since it's an extension of this axis - is located smack over the top of your head. If you leave the North Pole and travel south, you see the North Star getting lower in your sky. It keeps getting lower and lower as you continue southward - until you reach the equator. Here you see it on your northern horizon. As soon as you go even an inch south of the equator, you stop seeing Polaris because your view of it is blocked by the bulge of Earth's northern hemisphere. So, nobody south of the equator sees this star.

If you're one degree north of the equator, you see Polaris one degree above your horizon. (You might want to remember that there are 360 degrees in the circle you could draw around our Earth.) If you're two degrees north of the equator, you see Polaris two degrees above your horizon, and so on up. Here on Maui we're 21 degrees north of the equator. New York, Chicago and Seattle are twice as far from the equator as we are - at 42 degrees north. So if you're in one of these cities looking for Polaris, you'll find it twice as high in your sky as we see it here.

What migrating birds know about the sky is far, far beyond what we can explore here in a few minutes, so we've only begun to honor their intelligence and skill. Birds understand what our navigating Polynesians understood: if you want to find your way on this planet, you need the stars. Fortunately, you have more time to look at them now during this upcoming season of the long nights. And I hope you're enjoying the opportunity!

This is Harriet Witt, your guide for this little ride on our passenger planet. You can find what you've just heard here -- along with other maps of our cosmic journey -- at passengerplanet.com