Buzz
For centuries, experienced travelers above the equator have relied on the night sky, not modern tools like GPS or compasses, to determine the northern direction.
To the naked eye, stars seem to trace large circular paths around a stationary point of light nearly aligned with the North Pole. This guiding light aligns almost perfectly with Earth's rotational axis, though it deviates by approximately .7 degrees. Known as the North Star or Polaris, it also goes by numerous other names.
Interestingly, Polaris isn't a single star but a system of three stars.
Polaris, found in the Ursa Minor constellation, is a three-star system. The initial clue that the North Star was more complex than it seemed emerged in 1780 when William Herschel observed it through his telescope. Rather than seeing one star, Herschel (who would later identify Uranus) detected two nearby stars.
These stars are an unusual pair. Polaris A, a supergiant, is about six times the mass and 2000 times brighter than the Sun, overshadowing its companion, Polaris B. Located 323 light-years away, as determined in 2012 (earlier estimates suggested 434 light-years), their distance makes them appear as a single point of light to the unaided eye.
In 2006, astronomers using the Hubble telescope discovered that this pair was actually a trio when they identified a smaller third star, Polaris Ab, nearby. The gravitational pull between these three stars is immense, causing them to orbit a shared center of mass due to their close proximity.
Some researchers speculate that two additional stars, Polaris C and Polaris D, might be gravitationally linked to this trio, though they are situated farther away.
Despite its brilliance, Polaris ranks as the 50th brightest star in the night sky. Its brightness varies over time, and it is currently experiencing a particularly luminous phase, appearing up to 4.6 times brighter than in previous years.
Polaris will not remain the North Star indefinitely (in cosmic terms). Due to the gradual wobble of Earth's axis, Polaris will relinquish its position as the North Star in approximately 12,000 years, when the brighter Vega—once the North Star millennia ago—takes over once again.
