An unusual variable star, massive and unstable, which may explode as a supernova in the future. In 1677, Edmund Halley observed that this star brightened to 4th magnitude. By 1730, it reached 2nd magnitude, in 1827 it brightened to 1st magnitude, and in April 1843, it temporarily became the second brightest star in the sky with a brightness of -0.8 magnitude! In the following years, its brightness decreased, and since 1868 it has sometimes been invisible without a telescope, as its brightness ranged around 6th stellar magnitude. However, in the infrared region, it remains the brightest source in the sky.