This newly released image from the Gemini South telescope captures a well-known planetary nebula—a massive star fizzling out at the end of its life. These celestial displays often take on a circular or globular shape, but NGC 6302, as it’s formally known, bears a distinct resemblance to a butterfly. And what a beautiful butterfly it is.
I dabble in some amateur astronomy, and planetary nebulas are among my favorite targets. These objects have nothing to do with planets; early astronomers named them that because, viewed through small telescopes, they resembled distant gas giants like Saturn and Jupiter. M57, also known as the Ring Nebula, is a case in point, as you can see from my own image of the object below. The term “planetary nebula”—frustratingly—stuck, even though they are, in reality, glowing shells of gas ejected by dying stars.
The M57 Ring Nebula is a classic planet-shaped nebula, though in reality it shows an expanding shell of glowing gas cast off by a dying star. © George Dvorsky
Planetary nebulas sometimes take on an hourglass shape, or even a dumbbell, as the outer layers of a dying star get ejected into space. The vibrant colors we see in these nebulae often come from different gases glowing under intense ultraviolet radiation, with oxygen shining blue-green, hydrogen glowing red, and nitrogen appearing in shades of deep red or violet.
And in the case of NGC 6302—the Butterfly Nebula—the object takes on a butterfly-like form. Astronomers working with the Hubble Space Telescope imaged the object back in 2020 (shown below), but the new image, captured by the Gemini South telescope in Chile, offers a distinctly different perspective.
Hubble’s view of the Butterfly Nebula in 2020. ©NASA, ESA, Joel Kastner (RIT)
As the NOIRLab release points out, the Butterfly Nebula, located between 2,500 and 3,800 light-years away, formed from the death throes of a Sun-like star. Before collapsing into a white dwarf, the star expanded into a red giant roughly 1,000 times the size of our own Sun. As its outer layers bled into space some 2,000 years ago, slower-moving gas spread outward along the equator, forming a thick, dark ring of material. At the same time, gas spewing perpendicular to this band was funneled into what we now see as the object’s wing-like lobes.
Faster stellar winds then tore through these earlier gas outflows, smashing into them at speeds reaching 1.86 million miles per hour (3 million kilometers per hour). It’s this process that creates the dazzling ridges and pillars seen in the Butterfly Nebula. The intense radiation emanating from the central white dwarf is now heating the surrounding hydrogen, nitrogen, and oxygen to over 20,000 degrees Celsius, resulting in those vivid colors.
The International Gemini Observatory is marking the 25th anniversary of the telescope. Students in Chile chose this particular image through the Gemini First Light Anniversary Image Contest, part of the NOIRLab Legacy Imaging Program. This project is dedicated to producing science-grade color imagery from the observatory’s 8.1-meter telescope on Cerro Pachón.