In skylore, the star Alphard (Alpha Hydrae) represents the orange Heart of the Water Snake in the constellation Hydra. For this reason, it is sometimes called Cor Hydrae or Hydra’s Heart. Alphard is the only star of any noteworthy brightness in Hydra, but Hydra itself is distinctive for being the longest of all 88 constellations. On March, April and May evenings, this great star pattern stretches across the entire sky.
Like so many skywatchers before you, you’ll grow to love seeing Alphard ascending in the early evening in late February and March. Alphard is located in the front part of the Water Snake, and it’s up when darkness falls by the time of the March equinox.
The rest of the Water Snake is a long thin constellation made up of dim stars, which can be seen rising throughout the evening at this time of year. The entire Snake isn’t up completely until after midnight in March. So Alphard is like a herald to the rest of the Snake, which ascends in the sky like a snake charmer’s cobra from a basket. There is something about Alphard – some combination of its orange color and not-too-showy brightness – that looks friendly.
And, after all, Alphard is the Heart of Hydra, the Water Snake.
Do you know the constellation Leo the Lion – and its famous backwards question mark asterism? If so – on an evening in March, April or May – look along the sun’s path for Leo. Then, from Northern Hemisphere locations, look southward for Alphard to Leo’s lower right. You’ll find Alphard not far from Regulus, Leo’s brightest star. Alphard is not as bright as Regulus, but it’s a distinctive orange color.
Much like Fomalhaut six months from now, Alphard is said to be a lonely star. It beams as the sole bright light in a sea of dim stars in its part of the sky. The Arabic name Alphard translates as the Solitary One.
Look at Alphard with binoculars to discern its orange color. Alphard’s color shows that it is entering into the autumn of its years, like the color of the orange stars Pollux and Arcturus, and the ruddy star Aldebaran. Old stars’ colors are reminiscent of the orange color of autumn leaves. Like Pollux, Arcturus and Aldebaran, Alphard will shed its outer layers someday soon (by astronomical standards) and shrink into a dead white dwarf star.
Pollux, Arcturus and Aldebaran appear brighter in our sky than Alphard, but that’s because they are so much closer to us. Alphard is actually intrinsically brighter than any of these stars. Yet it appears fainter, because it lies some 180 light-years away, while Pollux, Arcturus and Aldebaran reside at 34, 37, and 65 light-years, respectively.
Bottom line: In Northern Hemisphere spring (southern autumn), come to know the star Alphard, starry Heart of the Snake in the constellation Hydra.
Bruce McClure has served as lead writer for EarthSky's popular Tonight pages since 2004. He's a sundial aficionado, whose love for the heavens has taken him to Lake Titicaca in Bolivia and sailing in the North Atlantic, where he earned his celestial navigation certificate through the School of Ocean Sailing and Navigation. He also writes and hosts public astronomy programs and planetarium programs in and around his home in upstate New York.