Sunday, August 21, 2022


Using the stars of the Summer Triangle can help to navigate the summer skies and recognize the brightest constellations. This is not a constellation, but an asterism, that is a group of particularly bright stars that due to their configuration (in this case that of a triangle) stand out compared to the less bright background stars.

The Summer Triangle, which can be admired after sunset from early June until late autumn, is composed of Vega, Altair and Deneb. These are respectively the brightest stars of the constellations of Lira, Aquila and Cigno.

The triangular form of this asterism is easily recognizable to the southeast above the luminous path of the Milky Way. In particular, it is on the same line of sight as a region rich in dark nebulae known as the Swan Slit.

Since the stars that compose it are very bright, the Triangle can also be seen in a sky with light pollution.

At the top of the triangle is located Vega, which consequently is the first of the three stars to arise and the first to be detected. As shown by the image from Vega you can reconstruct the shape of the Lira, while once recognized Altair and Deneb are the Eagle and the Swan. 

As shown in the diagram of the image, in skies without light pollution the Summer Triangle can be used both to identify less luminous constellations such as Sagitta and the Dolphin and to find some objects of the deep sky. The two crosses in the figure, for example, indicate the Ring Nebula (M57) and the Handlebar Nebula (M27), two of the most beautiful planetary nebulae in the sky.

(Image credits: via Wikipedia)

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