- Since any three points make up the corners of a triangle it is unsurprising, if somewhat unimaginative, to find a triangle among the constellations. Aratus and Eratosthenes knew this constellation as Δελτωτόν (Deltoton), because its shape resembled a capital delta (Δ), while Ptolemy in the Almagest listed it as Τρίγωνον (Trigonon), triangle.
- Eta Aquilae (stars.astro.illinois.edu)
ETA AQL (Eta Aquilae). Lying almost exactly one degree north of the celestial equator, this quite- wonderful mid-fourth magnitude (nominally 3.90) star in Aquila (the Eagle) glides across the sky just 8 degrees to the south of much brighter first magnitude Altair.