Using the Hubble Space Telescope, astronomers uncovered startling new images of two planetary nebulae at different stages of life. The images, similar to snapshots in a family photo album, promise to reveal critical new information about the process of planetary nebula formation.

The nebulae in Hubbles most recent images are particularly interesting because they differ significantly in age and developmental stage. Whereas the first and older nebula, the circular IC 418, is a few thousand years old, IC 418s baby sister, CRL 618, is only between several hundred and 1,000 years old.

The older IC 418 which is also known as the Spirograph Nebula because of its resemblance to the circular geometrical patterns of the same name is more well-formed because it has had longer to develop. In contrast, the younger CRL 618 is actually known as a protoplanetary nebula, or precursor of a planetary nebula.

Though CRL 618 and IC 418 dont share much in the way of looks, astronomers say the two are thought to form in a similar manner. Planetary nebula result when sun-like stars reach the end of their lives. After these stars become bloated red giants, they begin to slough off excess mass in the form of a "shell" of gases and dust. It is this dust that eventually forms a planetary nebula.

But according to astronomer Raghvendra Sahai, a researcher at NASAs Jet Propulsion Laboratory in Pasadena, California, thats where the similarities end and the mysteries begin.

"Its amazing you start with something as simple as a sun, and then the stars do all this strange stuff and we havent a clue why," said Sahai.

One of the aspects of planetary nebula formation that Sahai and his colleagues are actively trying to figure out, is why and how the nebulae form different shapes, sizes, structures and symmetries.

Planetary nebulae are expanding shells of gas that surround aged stars. Though they are so named, there is no relation between planetary nebula and planets. They were dubbed by the 18th-century astronomer William Herschel, who thought their generally circular shape looked similar to planets as seen through a telescope.

But although these objects are some of the most beautiful in the universe, scientists still do not know how exactly planetary nebula form. As such, astronomers are extremely interested in Hubbles new pictures, as they are aiding in the discovery of these objects shape and inner workings.

The Spirograph Nebula, in particular, provides astronomers with an interesting case study. Not only does it have an irregular symmetry pattern; it also contains a smaller shell inside the main nebular shell, which puzzles astronomers.

"Inner geometric structures are common in planetary nebula we often see shells, rings, and little hourglasses," said Sahai. "But we really dont have a good way of explaining them yet. People have a lot of ideas, but nobody really knows whats correct. Weve been really sort of scratching our heads."

The young protoplanetary nebula CRL 618 is also a bit of an enigma to astronomers because it represents the mysterious transition between a stars red giant phase and its planetary nebula phase.

Hubbles latest CRL 618 image shows that it is a complex of gaseous jet-like protrusions emanating from a central core. Speeding along at over 430,000 miles (700,000 kilometers) per hour, these jets are moving so fast, astronomers say that they may actually be able to detect measurable changes in the jets structure.

Astronomers predict CRL 618 will become a fully developed planetary nebula within the next several thousand years. Currently, however, the eventual shape and symmetry of this nebula is unknown. Still, researchers say that Hubble and future space telescopes may give astronomers major insights as to CRL 618s mature state.