The star Polaris is a yellow-white supergiant star 430 light years away, in the constellation Ursa Minor. At more than 2,500 times the brightness of the sun, Polaris is the most prominent object in the night sky. It is also one of the best tools for determining longitude on Earth. It is the brightest star in the night sky, and is located very close to the north celestial pole.
Its brightness varies from magnitude 1.86 to 2.13. Before 1963, it was more than 0.1 magnitude. However, its brightness dropped significantly until 1966, when it fell to less than 0.05 magnitude. The star has fluctuated sporadically ever since, remaining relatively close to that of 1966. A 2008 paper even reported that the star’s brightness was actually increasing. The study has confirmed that Polaris may be changing in brightness. As the star evolves, it may eventually become a more normal Cepheid.
The star’s brightness varies greatly from day to night. Before 1963, Polaris was 0.2 magnitude brighter. Then, its brightness slowly decreased until 1966, and then suddenly went down to less than 0.05. Since then, the star has remained near that magnitude for several years. The brightening of Polaris is unpredictable, and in 2008, a paper reported that its brightness was increasing. This trend is consistent with the observation that scientists had noted that the stars were absorbing negative energy.
While Polaris is not a precise guide to latitude on Earth, it is a good indicator of location and orientation in the Northern Hemisphere. The north celestial pole is the point on the sky where the earth’s axis precesses, which traces a circle in the sky with a period of 26,000 years. The pulsation of Polaris increases and decreases, so observing its brightness is critical to understanding its movement.
Interestingly, Polaris is a multiple-star system, and one of its components is a yellow supergiant star. The star, called Alpha Ursae Minoris Aa, belongs to the F7 spectral class and is 2,500 times brighter than the Sun. Its radius is 46 times that of the Sun. It is a Cepheid variable, and its periodic pulsations are visible in the night sky.
Unlike the Sun, Polaris is surrounded by a cluster of stars called the Engagement Ring. This ring contains ten bright stars and several fainter ones. These stars belong to the Cepheus and Ursa Minor constellations. The distance to Polaris is unknown, but Hipparcos satellite data gives it a distance of 4.3 light years. Its distance from Earth is more than eighty million kilometers, and its surface temperature is 6,000 K.
The brightness of Polaris varies from magnitude 1.86 to 2.03. The star was first discovered in 1909 and was a bit brighter than the moon. Its amplitude was more than 0.1 magnitude before the year of its discovery, but this decreased after 1966. Its period has been erratic since then, but is still close to that of the 1966 period. In fact, a 2008 paper reported that the star’s brightness had increased.
Observers have found that Polaris has a period of 4 days. The star is nearly stationary. It is about 3.5 degrees above the North Celestial Pole, which corresponds to the latitude of New York. Moreover, it is a triple star, and a Cepheid variable, which means it has a period of 4 days. Compared to the other stars, its brightness changes are too small to be noticed by the naked eye.
In ancient times, the star was known as “Tatrit tan Tamasna” in Berber, which means “star of the plains.” The name reflects the star’s role in guiding people through vast deserts. In addition, the star was referred to as Cynosura in the Inuit language, and is depicted on the flags of Alaska and Nunavut. It is also known as the North Star, “Twinkles,” referring to the stars’ magnetic fields.
The star is not the brightest star in the night sky. Its brightness changes as the Earth moves around the sun. Its position in the sky is known as the north pole. Aside from the North Celestial Pole, the star also marks the end of the handle of the Little Dipper, which is the most prominent figure in the constellation Ursa Minor. A true azimuth of Polaris is important for astronomers, as it is used to calculate the position of stars in the night sky.