Piercing Eye

Credit: NASA and ESA

A dra­matic, pierc­ing eye gazes back at us from the sky in this image of NGC 3918 from NASA’s Hub­ble Space Tele­scope.

Explore the col­or­ful lay­ers of gas and dust of this plan­e­tary neb­ula. These bub­bles sur­round a pin­point of light at the cen­ter; the dying rem­nants of a star that once was much like our Sun. For most of its life, the star con­verted hydro­gen into helium in its core in a process called fusion. Once that hydro­gen runs out after bil­lions of years, the star puffs up to become a red giant, engulf­ing it inner plan­ets. A red giant is nearly the last phase of life for a star like our Sun. The core can start to fuse helium into car­bon but this process doesn’t last very long. When that process ends, huge clouds of gas, the outer lay­ers of the star, are puffed out into space as the star con­vulses. Even­tu­ally, all that remains is the white-hot, dead core of the star. Astronomers call this a white dwarf. They are small; about the size of the Earth, and they weigh about as much as half a Sun. In about four bil­lion years, our Sun will enter this stage in its life. The white dwarf is a dead star that will even­tu­ally fade into a piece of warm, black ash.

Intense radi­a­tion from the tiny rem­nant causes the neb­ula to glow. The glow lights up the lay­ers of the neb­ula show­ing us strange and irreg­u­lar shapes. In the case of NGC 3918, it looks like the shells of gas were thrown off in two huge waves. But astronomers study­ing the neb­ula believe the bub­bles were formed at the same time. The mate­r­ial was thrown away from the star at dif­fer­ent speeds. Jets shoot out from the ends of the nebula.

NGC 3918 is found only about 4,900 light-years from Earth toward the con­stel­la­tion Cen­tau­rus. The light from this plan­e­tary neb­ula has trav­eled nearly 5,000 years ago to fall on our eyes here on Earth. Leave a com­ment below and tell us what you see in this image.