The Red Square Nebula is a celestial object located in the area of the sky occupied by star MWC 922 in the

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the earliest constellation ...

Serpens. The first images of this bipolar nebula, taken using the

Mt. Palomar Palomar Mountain ( ; es, Monte Palomar ) is a mountain ridge in the Peninsular Ranges in northern San Diego County. It is famous as the location of the Palomar Observatory and Hale Telescope, and known for the Palomar Mountain State Park. Histo ...

Hale telescope in

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, were released in April 2007. It is notable for its square shape, which according to

Sydney University The University of Sydney (USYD), also known as Sydney University, or informally Sydney Uni, is a public research university located in Sydney, Australia. Founded in 1850, it is the oldest university in Australia and is one of the country's six ...

astrophysicist Peter Tuthill, makes it one of the most nearly discrete-symmetrical celestial objects ever imaged. The explanation proposed by Tuthill and his collaborator James Lloyd of

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is that the square shape arises from two cone shapes placed tip-to-tip, as seen from the side. This also explains the "double-ring" structure seen in

SN 1987A SN 1987A was a type II supernova in the Large Magellanic Cloud, a dwarf satellite galaxy of the Milky Way. It occurred approximately from Earth and was the closest observed supernova since Kepler's Supernova. 1987A's light reached Earth on ...

. A series of faint spokes radiate from the center of the structure. One possible explanation is that these spokes are shadows cast by periodic ripples or waves on the surface of an inner disk close to the central star. There is no clear explanation of how the central star could produce the nebula's shape:

Towards the end of their lives, many low-mass stars, like the Sun, slough off their outer layers to produce striking 'planetary' nebulae. But the hot star at the heart of the Red Square nebula, called MWC 922, appears to be relatively massive, suggesting another process formed its signature shape. "How did all this beautiful, crisp structure form?" asks Peter Tuthill of the University of Sydney in Australia. "This is the million dollar question."

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* * * * * {{DEFAULTSORT:Red Square Nebula Protoplanetary nebulae Serpens (constellation) B(e) stars