Horse Bubbles

Credit: NASA, ESA, and the Hub­ble Her­itage Team (STScI/AURA)

Whether you see horses, dol­phins or a jel­ly­fish, the green and blue bub­ble of NGC 2371 catches the eye in this NASA Hub­ble Space Tele­scope image.

NGC 2371 is the glow­ing remains of a star much like the Sun. Known as a plan­e­tary neb­ula, space bub­bles like this are cre­ated when a star reaches the end of its life. Astronomers in the 16th and 17th cen­turies found many of these objects as they were search­ing the heav­ens for plan­ets. These looked so much like plan­ets in their tele­scopes they began to refer to them as plan­e­tary nebula.

The cen­tral star, seen in the cen­ter of the neb­ula, has burned up all of its nuclear fuel. The star prob­a­bly bal­looned into a huge, red giant star but then ejected its outer lay­ers. As the bub­ble of gas and dust expands into space, it cools and even­tu­ally will fade. The core star will also cool into a white dwarf. But today, the core star shines as a super-hot star with a tem­per­a­ture of more than 240,000 degrees Fahren­heit. Ultra­vi­o­let light from the core star causes the gas in neb­ula to glow

Explore the image and find the numer­ous pink dots. The pink areas jet out from the star in oppo­site direc­tions and mark dense, cooler knots of gas and dust.

NGC 2371 lies about 4,300 light-years away from Earth toward the con­stel­la­tion of Gem­ini, the Twins. The dis­tance from one pink jet to the other is about one-light year. It would take light a whole year to travel from one side of NGC 2371 to the other.