Astronomy Picture of the Day—20181214

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2018 December 14

Arp188 and the Tadpole's Tail

ImageCredit: Hubble Legacy Archive, ESA, NASA; Processing: Faus Márquez (AAE)

Explanation:Why does this galaxy have such a long tail? In this stunning vista, based onimage data from the Hubble Legacy Archive, distant galaxies form a dramaticbackdrop for disrupted spiral galaxy Arp 188, the Tadpole Galaxy. The cosmictadpole is a mere 420 million light-years distant toward the northernconstellation of the Dragon (Draco). Its eye-catching tail is about 280thousand light-years long and features massive, bright blue star clusters. Onestory goes that a more compact intruder galaxy crossed in front of Arp 188 -from right to left in this view - and was slung around behind the Tadpole bytheir gravitational attraction. During the close encounter, tidal forces drewout the spiral galaxy's stars, gas, and dust forming the spectacular tail. Theintruder galaxy itself, estimated to lie about 300 thousand light-years behindthe Tadpole, can be seen through foreground spiral arms at the upper right.Following its terrestrial namesake, the Tadpole Galaxy will likely lose itstail as it grows older, the tail's star clusters forming smaller satellites ofthe large spiral galaxy.