How many Polaris are there in the sky?

For thousands of years, Polaris has been like a road sign, guiding people. In our knowledge base, Polaris is a bright star near the north celestial pole, but in fact, Polaris has more than 1 stars. 1780, the British astronomer Sir William Herschel (the father of stellar astronomy) discovered that two seemingly close stars could be observed at the position of the North Pole star. This star named Polaris A is six times bigger and 2000 times brighter than the sun, while its companion Polaris B is smaller than it. In other words, the Polaris that we see on the earth is actually two stars. However, due to the distance from the earth and the high brightness of Polaris A, we can't distinguish the boundaries between them with the naked eye. In 2006, through the Hubble telescope, scientists found that there were not two Polaris, but three, and the third star was named Polaris Ab. Observations show that although Polaris Ab is closer to Polaris A, it is difficult to be found because of its small size and low brightness. Scientists have found that there is great gravity between these three stars, rotating around the same center. So the familiar Polaris should be composed of three stars. That's not all. Some experts even think that Polaris C and Polaris D should still exist, but these two stars are farther apart, so they have not been observed. Anyway, now we know that the northern lights seen on the earth at least include the contribution source of Polaris A and Polaris B: the mystery of science.