April 27, 1998
The stars above are ancient, but your chance to be here is exquisitely temporary.
IC 4406: A Seemingly Square Nebula
Birthday · April 27, 1998
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APOD published April 27, 1998. Full image credits are on the original APOD entry below. A publication-date match, not a photo taken on your date. Independent of NASA.
How can a round star make a square nebula? This conundrum came to light with the discovery of planetary nebulae like IC 4406. IC 4406 is most probably cylindrical, with its square appearance the result of our vantage point in viewing the cylinder. Hot gas is known to be flowing out the ends of the cylinder, while filaments of dark dust and molecular gas lace the bounding walls. The star primarily responsible for this interstellar sculpture can be found in the nebula's center. In a few million years, the only thing left visible in IC 4406 will be a fading white dwarf star.