expression, noun
Summer Triangle
An asterism formed by the bright stars Vega, Altair, and Deneb, visible in the summer night sky in the Northern Hemisphere.
夏の大三角は、ベガ、アルタイル、デネブの三つの星でできている。
The Summer Triangle is made up of the three stars Vega, Altair, and Deneb.
From 夏 (summer) + の (possessive particle) + 大三角 (large triangle). A direct calque of the English astronomical term 'Summer Triangle'.