The visible-light Hubble Space Telescope images of the Ring Nebula are iconic enough, but layering on infrared data brings out even more detailed structure.
This is a composite of the visual-light observations from NASA's Hubble Space Telescope, paired with infrared data from the ground-based Large Binocular Telescope in Arizona. The nebula is about 2,000 light-years away in the constellation Lyra. The ring measures roughly one light-year across.
The tiny white dot in the center of the ring is a white dwarf, irradiating surrounding gas. The dwarf is the remnant of the star that exhausted its hydrogen fuel, shedding off layers of helium about 4,000 years ago. The helium glows blue where it is hottest, fading through the rainbow to a cool red glow at the edges of the ring.
The nebula is expanding at about 43,000 miles an hour. The outer ring formed as faster moving gas slammed into slower-moving material; the center is still expanding faster than the main ring. Expansion will continue for another 10,000 years until it is so diffuse and faint that it merges with the interstellar medium.
The detailed view reveals dark, irregular knots along the inner ring. These tentacles are dense strands of gas that are more resistant to erosion by the waves of ultraviolet light unleashed by the star. Astronomers lined up the knots with a shadow effect of spikes of bright light around the main ring.
We talked about this image last year when it was first released, but it's too pretty to not share with the Space subsite's new readers. Read more about this composite image of the Ring Nebula on the NASA website. Image credit: NASA & ESA