✧ Hydra

  Hydra is an asterism in Sextans.

                                              ⣠···
                                           ·⠤·⠁
                                           ⠘⡆
                                          ⢀⣠•
                                       ⣠··⠋
                                   ⢀·⠤·⠁
                                  ⢀⡞
                                 ⢀⡞
                 ⢀⣠·⠤⠤⣄⣀⣀⡀      ⣠·
              ⢀⣠⠖⠋       ⠉⠉⠉⠓⠒⠒·⠁
           ⢀⣠⠖⠋
        ⣀⡤·⠋
      ·⠋⠁

  Type            Asterism
  Constellation   Sextans
  Stars           18

  More information about Hydra

  Hydra stretches a quarter of the way around the sky, from a small head
  south of the constellation Cancer to a tail that reaches beyond Spica,
  and it takes more than six hours to rise completely. The only star in it
  that stands out is Alphard, and its name explains why: it is the Arabic
  الفرد, "the solitary one", and it sits in an empty stretch of sky with
  nothing near it to compete. Everything else in the figure is faint.

  Etymology
  From        Greek
  Reading     hydra  ·  ὕδρα
  Literally   water snake

  The evolution of Hydra over time

  -50,000 years
                                                                                   Hydrobius
                                                                                ⣀⣀·⣄⣀
                                                                             ⢀⡔⠋··⠉ ·⡙·
                                                                           ⣀⠖⠁       ·· Minchir
                                                                          ·⠁
                                                                          ⢳
                                                                          ⠘⡄
                                                                           ⢧
                                                                ⢠⣀       ⢀⡤• Alphard
                                                               ⡠⠃·⠉⠒⠦⣄⡀⣀⠔⠁
                                                              ·⠁      ⠈·
                                                            ⢠⠎
                                                          ⢀⠔·
                                                        ⢀⠔⠁
                                                      ⢀⠔⠁
                           ⢀⣠⠴⠒·⠤⢄⡀                 ⢀⠔⠁
                       ⢀⣠⠴⠚⠉      ⠈⠉⠒⠦⢄⣀          ⢀⠔⠁
                   ⢀⣠⠴⠚⠉                ⠉⠓⠢⠤⣀⡀   ⡴·
                ⢀⡠⠒⠉ ·                       ⠉⠑⠲·
              ⠤⠚⠁
              ·
  
  now
                                                                                   Hydrobius
                                                                                ⣠⠤·⠤⣄
                                                                             ⣀⠔⠋ ··⣆·
                                                                         ⢀⡠⠔⠊·     ·· Minchir
                                                                       ·⠊⠁
                                                                       ⠈⢆
                                                                        ⠘⡄
                                                                        ⢀⡹• Alphard
                                                                 ⡀    ⢀⡰⠊
                                                               ⢠⠎·⠑⠢⢄⠴⠉
                                                         ·⠲⠤⠤⠤⠞⠁     ·
                                                       ⢀⡞     ·
                                                      ⢀⡞
                                                     ⢀⠎
                                                    ⢀⠎
                          ⢀⠴·⠤⢤⣀⡀                  ⢠⠊
                       ⢀⠴⠚⠁     ⠈⠉⠒⠢⠤⣄⣀           ⢠⠃
                    ⢀⡤⠖⠁               ⠉⠑⠒⠦⠤⣀⡀ ⢀⡠⠖·
                  ⡠·⠁                        ⠈⠉·
               ⢀⠔⠋
                ·
  
  +50,000 years
                                                                                  Hydrobius
                                                                              ⢀⡴·⠒⠤·
                                                                            ⢀⡔⠃ ··⠼⠁
                                                                          ⢀⠔⠁     · Minchir
                                                                    ⠠·⠤⠤⠤⠔⠁
                                                                     ⠘⢄  ·
                                                                      ⠈⢦
                                                                      ⡠⠎• Alphard
                                                                    ⣠⠎⠁
                                                      ·⠒⢤⣀     ⣀⠔·⢄⠞
                                                     ⢸    ⠉⠒⠤⣠⠔⠁  ·
                                                     ⡇       ·
                                                    ⢰⠁
                                                    ⡞
                                                   ⢠⠃
                        ⢀⡠⢤⣀⣀                      ⡜
                      ⢀⠴⠉·  ⠈⠉⠉⠒⠒⠦⠤⣄⣀⡀            ⢀⠇
                    ⢀⠔⠉              ⠈⠉⠑⠒⠒⠤⠤⣄⣀⡠⠤⠒⠊⠉·
                  ⣠⠜⠁                        ·
                 ·
                 ·

  Over 50,000 years either way the longest side of this figure changes by 5%, and the furthest
  any of its stars travels is 4.7 degrees. Hydrobius, HR 3665, Alphard, HR 3845, HR 3903, HR
  4232, HR 5020 and HR 5287 drift the opposite way to the other 10, which travel together.
  Proper motion only: this is the shape changing, not the sky turning or the pole moving.

  curl 'skymap.sh/Hydra/evolution.gif'

  where it is tonight:  skymap.sh/Hydra