Starwatch: northern autumn brings the loneliest star

Stuart Clark
Starwatch Chart 23 September 2019 Fomalhaut

If there is one star that signposts autumn in the northern hemisphere, it’s Fomalhaut. Now is a good time to start your search for this bluish-white star. The chart shows the view at midnight (BST) as 23 September becomes the 24th, looking south. With a clear horizon, Fomalhaut will appear low and isolated as there are no other stars of comparable brightness around it. This has led astronomers to nickname it “the loneliest star”. The star itself is about twice the size and mass of the sun, yet pumps out about 16 times more light than our star. At a distance of 25 light years, it is a relatively nearby star. It is the brightest star in the faint southern constellation of Piscis Austrinus. While it is relatively easy to see, the other stars in this constellation are difficult to pick out from northern latitudes because they are so faint and appear so low in the sky. The star’s name is Arabic and translates literally as “mouth of the whale”.