Resembling a nightmarish beast rearing its head from a crimson sea, this monstrous object is actually an irnocuous pillar of gas and dust. Called the Cone Nebula (NGC 2264), this giant pillar resides in a turbulent star-forming region. This picture, taken by the newly installed Advanced Camera for Surveys (ACS) aboard Hubble Space Telescope (HST) during Space Shuttle STS-109 mission in March 2002, shows the upper 2.5 light-years of the nebula, a height that equals 23 million roundtrips to the Moon. The entire nebula is 7 light-years long. The Cone Nebula resides 2,500 light-years away in the constellation Monoceros. Radiation from hot, young stars (located beyond the top of the image) has slowly eroded the nebula over millions of years. Ultraviolet light heats the edges of the dark cloud, releasing gas into the relatively empty region of surrounding space. There, additional ultraviolet radiation causes the hydrogen gas to glow, which produces the red halo of light seen around the pillar. A similar process occurs on a much smaller scale to gas surrounding a single star, forming the bow-shaped arc seen near the upper left side of the Cone. This arc, seen previously with the HST, is 65 times larger than the diameter of our solar system. The blue-white light from surrounding stars is reflected by dust. Background stars can be seen peeking through the evaporating tendrils of gas, while the turbulent base is pockmarked with stars reddened by dust. Credit: NASA, H. Ford (JHU), G. Illingworth (USCS/LO), M. Clampin (STScI), G. Hartig (STScI), the ACS Science Team, and ESA.

The Blue Ring Nebula is thought to be the product of two stars merging into one. The collision of the bodies ejected a cloud of hot debris into space. A disk of gas orbiting the larger star cut the cloud in half, creating two cones that are moving away from the star in opposite directions. The base of one cone is moving almost directly toward Earth, while the other is moving almost directly away. Magenta represents optical light from the shockwave at the front of the expanding debris cones, outlining the two cone bases at their widest points. Blue represents far-ultraviolet light (not visible to the human eye) and comes from gas behind the shockwave. As the gas expands and cools, it forms hydrogen molecules that interact with the interstellar medium and emit only far-ultraviolet light. These emissions are visible only where the cones overlap (as seen from Earth), forming the blue ring around the central star. Movie available at https://photojournal.jpl.nasa.gov/catalog/PIA23868

The Blue Ring Nebula was discovered in 2004 by NASA's Galaxy Evolution Explorer (GALEX) mission. Astronomers think the nebula was created by the merger of two stars, and that we are seeing the system a few thousand years after the merger, when evidence of the collision is still apparent. The blue light in the image shows the debris cloud created by the merger. As the hot cloud of material expanded into space and cooled down, it formed hydrogen molecules that collided with the interstellar medium (the particles occupying the space between stars). These collisions caused the hydrogen molecules to radiate far-ultraviolet light, which was detected by GALEX. Yellow indicates near-ultraviolet light, also detected by GALEX, which is emitted by the star at the center of the nebula and many surrounding stars. Infrared light observed by NASA's Wide-field Infrared Survey Explorer (WISE) is also shown in red, and is primarily emitted by the central star. Detailed analysis of the WISE data revealed a ring of debris around the star – further evidence of a merger. Magenta indicates optical light — light visible to the human eye — collected using the Hale Telescope. This light comes from the shockwave at the front of the expanding debris cones. The optical light helped astronomers discover that the nebula actually consists of two cones moving away from the central star. The base of one cone is moving almost directly toward Earth, while the other is moving almost directly away, and the magenta light outlines the two bases. The blue region in the image shows where the cones overlap; the non-overlapping regions are too faint for GALEX to see. Figure A shows the orientation of the cones to Earth and the way they appear to overlap. https://photojournal.jpl.nasa.gov/catalog/PIA23867

This image was compiled using data from NASA's Spitzer Space Telescope using the Infrared Array Camera (IRAC) and the Multiband Imaging Photometer (MIPS) during Spitzer's "cold" mission, before the spacecraft's liquid helium coolant ran out in 2009. The colors correspond with IRAC wavelengths of 3.6 microns (blue), 4.5 microns (cyan) and 8 microns (green), and 24 microns (red) from the MIPS instrument. The green-and-orange delta filling most of this image is a nebula, or a cloud of gas and dust. This region formed from a much larger cloud of gas and dust that has been carved away by radiation from stars. The bright region at the tip of the nebula is dust that has been heated by the stars' radiation, which creates the surrounding red glow. The white color is the combination of four colors (blue, green, orange and red), each representing a different wavelength of infrared light, which is invisible to human eyes. The massive stars illuminating this region belong to a star cluster that extends above the white spot. On the left side of this image, a dark filament runs horizontally through the green cloud. A smattering of baby stars (the red and yellow dots) appear inside it. Known as Cepheus C, the area is a particularly dense concentration of gas and dust where infant stars form. This region is called Cepheus C because it lies in the constellation Cepheus, which can be found near the constellation Cassiopeia. Cepheus-C is about 6 light-years long, and lies about 40 light-years from the bright spot at the tip of the nebula. The small, red hourglass shape just below Cepheus C is V374 Ceph. Astronomers studying this massive star have speculated that it might be surrounded by a nearly edge-on disk of dark, dusty material. The dark cones extending to the right and left of the star are a shadow of that disk. The smaller nebula on the right side of the image includes a blue star crowned by a small, red arc of light. This "runaway star" is plowing through the gas and dust at a rapid clip, creating a shock wave or "bow shock" in front of itself. https://photojournal.jpl.nasa.gov/catalog/PIA23126