The constellation used to determine north is Ursa Minor, also known as the Little Dipper.

Here's why:

* Polaris, the North Star: The end star of the Little Dipper's handle, Polaris, is very close to the celestial north pole. This means it appears almost stationary in the sky, while other stars rotate around it.

* Finding Polaris: You can find Polaris by following the two stars at the end of the Big Dipper's bowl (Dubhe and Merak) upwards. They form a line that points to Polaris.

Important Note: Polaris is not perfectly aligned with the north celestial pole, but it's close enough to be a reliable guide for finding north.