Planetary Nebulae are usually very small objects in the night sky. Imaging them is a job for a scope with a narrow field of view, such as the 14 inch scope here at CSO. Last night, I was hoping to image an HII region called the Dolphin Nebula, but it was below the horizon. However, I did find another Dolphin Nebula that was visible, but instead of a larger, HII region, I found it was a small, planetary nebula and is sometimes called the Shrimp Nebula. It was a tiny object in the telescope field, so this is a very heavily cropped image. The object was first imaged in 1965 and was thought to be a supernova remnant. We now know it is a Planetary Nebula--a cloud of dust and gas expelled by a star as it dies of old age. Planetaries are usually symmetrical. The crescent shape of the Dolphin comes from its high speed. It is traveling at over 300,000 miles per hour through layers of interstellar medium, which distorts its shape. This image is composed of 200 x 30 second images stacked and processed.
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