13 lines
1.8 KiB
Markdown
13 lines
1.8 KiB
Markdown
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name: Hydra
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created_by: skybber
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created_date: 2021-06-29 07:04:57.175158
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updated_by: skybber
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updated_date: 2021-06-29 07:04:57.175389
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---
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After the star pattern of the Argo was split, Hydra became the largest constellation in the sky. It is an extraordinarily long constellation, stretching more than six hours in rectangular time, across 1/4 of the celestial sphere, roughly below the ecliptic. The head of Hydra borders the Little Dog on its western edge, so it can be observed even on winter evenings. The tail winds under the Sextant, Cup, Raven, Virgo, and ends up under the constellation Libra, which is a transitional constellation between spring and summer. One could almost say that when the head of Hydra sets, the tail is just rising. This is especially so in northern Europe. The head of Hydra is an attractive and striking stellar cluster of the constants δ, ε, ζ, η, ρ and σ Hydra (which have nothing in common with each other apart from this) lying north of the celestial equator, which fits within the field of view of most 7×50 triads. Its heart is formed by the red-orange star Alfard. The winding tail, best seen on clear dark nights because it contains mostly only 4-5mag stars, ends at the star 58 Hydra, southwest of σ Librae of Libra.
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Although the constellation extends outside the Milky Way, its size means that it contains a variety of remarkable objects. Most of these are galaxies, of course, but many are brighter than 10mag. Hydra also contains some nice planetary nebulae, a couple of globular clusters and one nice open cluster. Three objects are also in Messier's catalogue: M48, M68 and M83. The constellation also contains the galaxy cluster Hydra, one of the densest galaxy clusters. Its brightest member is the galaxy NGC 3311 (10.9mag).
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