Key Takeaways:
- Equuleus, also known as the Foal, is a small and faint constellation located southwest of Pegasus.
- Unlike many constellations, Equuleus lacks bright stars, nearby stars, prominent meteor showers, or Messier objects.
- Despite its inconspicuous nature, Equuleus is historically significant, included among Ptolemy's 48 original constellations in the Almagest.
- Locating Equuleus requires identifying Epsilon Pegasi and then searching approximately 7 degrees due west; its brightest star, Alpha, has a magnitude of 3.9.
We’ve all identified Pegasus in the sky, right? It’s easy to see the Great Square, notwithstanding that one of the stars belongs to Andromeda. The constellation Pegasus represents the mythological winged horse. But did you know that the sky holds a second horse? On Pegasus’ southwest border sits Equuleus — and, by the way, the official pronunciation is ek woo oo’ le us — the Foal.
By any reasonable standard, this is a weak constellation. It contains none of the 200 brightest stars, has no named star, none of the nearest stars, no meteor shower or Messier object, and it ranks 87th in size out of the 88 constellations that cover the sky. It was, however, one of the original 48 constellations of the Greeks. Ptolemy, who lived from 73 to 151 A.D., mentioned Equuleus in his great work, Almagest. And your ability to identify it will set you apart from your observing buddies.
This constellation covers a meager 71.64 square degrees of the sky. That’s only 0.174 percent. Put another way, more than 18 constellations the size of Equuleus could fit into the area of the sky’s largest constellation, Hydra the Water Snake.
To see the Foal, or at least the faint stars that form its figure, first find the magnitude 2.4 star Epsilon Pegasi. Then look 7° due west of Epsilon. (Note: 7° is the width of the field of view of 7×50 binoculars.) But don’t expect to see much. Equuleus’ brightest star — Alpha — glows at a disappointing magnitude 3.9. The fainter stars just north and just east of Alpha form the rest of the constellation.
Once you’ve found Equuleus, pat yourself on the back, check it off your list, and move on. You did it.
