Colors: Ring Nebula versus Stars

APOD: 2021 July 21 - Colors: Ring Nebula versus Stars

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2021 July 21
The picture shows the several images of the Ring Nebula separated by 
their colors. 
Please see the explanation for more detailed information.

Colors: Ring Nebula versus Stars
Image Credit: Robert Vanderbei (Princeton U.)

Explanation: What if you could see, separately, all the colors of the Ring? And of the surrounding stars? There's technology for that. The featured image shows the Ring Nebula (M57) and nearby stars through such technology: in this case, a prism-like diffraction grating. The Ring Nebula is seen only a few times because it emits light, primarily, in only a few colors. The two brightest emitted colors are hydrogen (red) and oxygen (blue), appearing as nearly overlapping images to the left of the image center. The image just to the right of center is the color-combined icon normally seen. Stars, on the other hand, emit most of their light in colors all across the visible spectrum. These colors, combined, make a nearly continuous streak -- which is why stars appear accompanied by multicolored bars. Breaking object light up into colors is scientifically useful because it can reveal the elements that compose that object, how fast that object is moving, and how distant that object is.

NGC 7814: Little Sombrero with Supernova
Thors Helmet
 

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