In this article, we’ll be sharing with you everything you need to know about the constellation of Equuleus, including how to find it, deep space objects contained within it and how to use it to find other night sky objects more easily.

The Constellation of Equuleus 

Greek astronomer Hipparchus (c. 190 BC – c. 120 BC.) named this constellation Equuleus, which is pronounced ee-KWOO-lee-us. It was known to several ancient cultures including Ancient China, where it was known as the ‘Black Tortoise of The North’. In Ancient Arabia it was known as ‘Al Fara al Awwal’ which means the ‘First Horse’.

Equuleus is one of the constellations that Greek astronomer Ptolemy cataloged over 2,000 years ago and its name means ‘little horse’ or ‘foal’ in Latin.

In one Greek myth, Equuleus is associated with Hippe, the daughter of Chiron (the centaur). Hippe became pregnant and then ran away from home to hide her pregnancy from her father. Chiron searched for his daughter. Hippe prayed to the Gods that her father wouldn’t find her and the Gods turned her into a mare and placed her in the night sky. Chiron is represented by the constellation Centaurus and Hippe continues to hide from him with only her head visible behind Pegasus.

In another Greek myth, Equuleus represents Cyllarus, the horse that Hera gave to Pollux. In a third myth, Equuleus represents Celeris, the foal given to Castor by Mercury. Celeris was either the brother or child of Pegasus.

To help you spot Equuleus, here’s what SkySafari 6 shows.

Equuleus as shown by SkySafari
Equuleus as shown by SkySafari. Click for full-screen.

Equuleus has an area of 72 square degrees making it the second smallest of the 88 recognized constellations; only Crux, the Southern Cross is smaller.

Alpha, Delta, and Gamma Equulei (Equuleus’s brightest stars) form an elongated triangle. Equuleus always rises before Pegasus so it’s sometimes known as the ‘First Horse’. 

The boundaries and neighboring constellations for Equuleus
The boundaries and neighboring constellations for Equuleus. Click for full-screen.

In the next section discover how to find Equuleus.

How To Find Equuleus In The Night Sky

Equuleus is part of the Heavenly Waters family of constellations and lies almost halfway between the northern and southern celestial poles. As such, it’s visible to observers at latitudes between +90° and -80°.

Northern Hemisphere observers can see this dim constellation in the evening between July and January. It is highest in the sky during September and October, as shown in the chart below. Southern Hemisphere observers can see it most easily in September and October.

The constellation of Equuleus is bordered by the constellations Aquarius, Delphinus and Pegasus

Equuleus at 10:00 p.m. on the 27th of September
Equuleus at 10:00 p.m. in late September. Click for full-screen.

To find Equuleus, do a naked-eye search for the Summer Triangle, consisting of the bright stars Vega, in Lyra, Deneb (Cygnus) and Altair (Aquila), and the Great Square of Pegasus.

Identify Altair (Alpha Aquilae) in Aquila. With that in sight, follow the trail of stars from Markab (Alpha Pegasi) at one corner of the Great Square to Enif (Epsilon Pegasi).

Draw an imaginary line ~28° long from Altair to Enif. This passes close by Delta Equulei and Gamma Equulei. Alpha and Beta Equulei are ~4° south of Delta Equulei and Gamma Equulei. You can estimate these distances with your hand at arm’s length.

To find the exact position of Equuleus for your location on any night, use software such as Stellarium (free) or SkySafari.

Equuleus’s Brightest Stars 

Equuleus, as we’ve already noted, is a very small constellation and, as such, has only a handful of stars visible to the naked eye. You can see them in the star chart below, and they’re described in more detail underneath that.

The brightest stars of Equuleus
The brightest stars of Equuleus. Click for full-screen.

Alpha Equulei (Kitalpha) – This variable double star is the brightest in Equuleus. The magnitude 3.94 yellow giant primary star is too close to its white main-sequence secondary component to be split in a backyard telescope, i.e. it is a spectroscopic binary. Its name means ‘Part of the Horse’ in Arabic and it is 186 light-years away from us.

Beta Equulei – This variable double star is 331 light-years away. The magnitude 5.15 white main-sequence primary and its magnitude 14.00 secondary component are 41 arcseconds apart.

Gamma Equulei – This variable double star is the third brightest star in Equuleus. The magnitude 4.71, yellow-white giant primary and magnitude 8.58 secondary components are 0.6 arcseconds apart.

This rotating variable ranges in magnitude from 4.58 to 4.77 every 12.5 minutes. Gamma Equulei is 118 light-years away and may be a multiple-star system. 

Delta Equulei – This double star is the second brightest star in Equuleus and is 60 light-years away. The magnitude 4.50 yellow main-sequence primary and its magnitude 5.52 main-sequence secondary components are 0.1 arcseconds apart. 

Star Hopping From Equuleus 

Equuleus is too small and too dim to be a good starting point for star hopping.

Objects To See Within Equuleus 

Equuleus does not contain any Messier objects or other deep sky objects suitable for small telescope users. 

Summary

Equuleus is the 2nd smallest constellation. This dim constellation contains only a handful of naked-eye stars and there are no deep sky objects for small telescope users.

Look for it as a small curiosity near its much larger horsey sibling, Pegasus. 

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