ABOUT THIS IMAGE:

The colorful, intricate shape of this NASA Hubble Space Telescope image reveals how the glowing gas ejected by dying Sun-like stars evolves dramatically over time.

This gaseous cloud, called a planetary nebula, is created when stars in the last stages of life cast off their outer layers of material into space. Ultraviolet light from the remnant star makes the material glow. Planetary nebulae last for only 10,000 years, a fleeting episode in the 10-billion-year lifespan of Sun-like stars.

The name planetary nebula has nothing to do with planets. They got their name because their round shapes resembled planets when seen through the small telescopes of the eighteenth century.

A young planetary nebula usually is small and is dominated by relatively cool, glowing nitrogen gas. Over thousands of years, the clouds of gas expand and the nebulae become larger. Energetic ultraviolet light from the star penetrates more deeply into the gas, causing the hydrogen and oxygen to glow more prominently. In the older nebulae, such as NGC 5307, hydrogen and oxygen appear more extended in these regions, and red knots of nitrogen are still visible.

NGC 5307 is a planetary nebula in our Milky Way Galaxy. It's distance from Earth is about 7,900 light-years. The image was taken with Hubble's Wide Field Planetary Camera 2 in February 2007. Like snowflakes, planetary nebulae show a wide variety of shapes, indicative of the complex processes that occur at the end of stellar life.

NGC 5307 shows a symmetrical structure with a suggestion of a spiral pattern, which may have been caused by the central dying star wobbling as it expelled jets of gas in different directions. Astronomers classify planetary nebulae like NGC 5307 as "point-symmetric," meaning that for each blob of gas around the star there is another blob on the opposite side. The bluish-green color shows the overall high level of excitation of the gas in this nebula, which is probably the oldest of the four. NGC 5307 resides in the southern constellation Centaurus.

This image is a composite of many separate exposures made by the WFPC2 instrument on the Hubble Space Telescope. Three filters were used to sample narrow wavelength ranges. The color results from assigning different hues (colors) to each monochromatic image. The red, green, and blue colors represent light emitted by nitrogen, hydrogen, and oxygen, respectively. In this case, the assigned colors are:

F502N ([O III])           blue           Oxygen
F656N (Halpha)        green          Hydrogen
F658N ([N II])            red             Nitrogen