Hydra

The Water Snake

The largest constellation in the sky, a long chain of faint stars that stretches from below Cancer to near Libra, with orange Alphard in the middle.

Chart drawn as the sky looks when you face the constellation: north is up and east is to the left. Dot size shows brightness, and color hints at temperature. The connecting lines are one common stick figure; other traditions draw them differently.

Best season: Spring
Best months: February through May, low in the south on late winter and spring evenings
Visibility: Visible from the United States, though much of its length stays low in the south
Abbreviation: Hya

How to find it

Look south of Cancer for the Hydra's head, a small ring of faint stars.
From there, follow a long, winding line of faint stars that stretches south of Leo and Virgo. Alphard is the one bright star standing alone in that stretch.

Brightest stars

Alphard (an orange giant, the heart of the Water Snake)

What to look for

Alphard, whose name means 'the solitary one,' for how isolated it looks in an empty region of sky.

Binocular and telescope targets

M48: an open cluster visible in binoculars
M83: a bright spiral galaxy, best from southern states

Using it to find other things

Hydra stretches below Cancer, Leo, and Virgo.

About this constellation

Hydra is the largest of the 88 constellations. Its length is its main feature, and it takes patience to follow the whole thing.

The easiest part to recognize is Alphard, which stands alone in a patch of sky with few other bright stars.

Related guides

Visibility depends on your latitude, the date, and the time of night. The months above assume a typical evening from the contiguous United States, so use a planetarium app to confirm what is up tonight. Never look at the Sun through binoculars or a telescope without a proper solar filter.

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