As I processed these two images the melody and lyrics of Jim Croce's "Time in a Bottle" drifted through my mind.

These are truly time pieces of the universe. They are different perspectives of what our sun may look like when it reaches the end of its life. They are called "planetary nebulae" because when the first of their kind was discovered, the astronomer viewing it thought it looked like Saturn with its beautiful rings.

As scientists studied more of these nebulae using better telescopes, they found that these are not planets at all. Rather they are the remnants of stars which no longer sustain nuclear fusion in their cores. However, the name stuck, so planetary nebulae are still what they're called.

The broad hourglass or apple core-shaped image is M27, the Dumbbell Nebula, in the summer constellation Vulpecula the Fox. The circular image is M57, the Ring Nebula in the constellation Lyra the Lyre, also prominent in the summer night sky. You can visualize the general 3D shape of a planetary nebula by pretending these two images are different perspectives of the same object.

When stars die, they collapse in on themselves. As they collapse, angular momentum makes them spin ever faster like an ice skater who draws her arms into herself as she twirls on the ice. Stars several times more massive than our sun die gloriously exploding as supernovae that are so powerful that they temporarily outshine the combined brilliance of all the stars in the galaxy they lived in.

Others, like our sun, die in a whimper as they waft away their outer atmospheres in a series of convulsions that can last thousands of years. If you look closely, you can count these convulsions that are lit up by the still intense radiation coming from the collapsed star in the center of the nebula.

The Dumbbell Nebula is an equatorial view of the spinning dying star known as a white dwarf about the size of our Earth. The Ring Nebula is a polar view. So the overall 3D hourglass shape of a planetary nebula is a time capsule of the death throes the star went through as it passed on to eventually reseed the interstellar medium with more "star stuff."

This stuff eventually collapses to form new star systems containing planets that may eventually spawn new life. You and I are made from the remains (periodic table of elements) of stars like these.

Gary Zientara is an astronomer and owner of Mount Sangre Observatory in Angel Fire, New Mexico.

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