Years ago I had an opportunity to visit the historic Grucci fireworks factory on Long Island. Artisan chemists there were hard at work crafting reactions that would detonate with just the right color and just the right shape; the whole place was surrounded by a high berm to contain any accidental explosions. Yet I couldn't help thinking--the universe creates even more spectacular colors, on a far grander scale, with no guidance and no effort. All we have to do is look in the right location. So yes, I'm planning to gather with my family tonight and watch traditional 4th of July fireworks, but I'm also holding on to that bigger thought. There are images of the cosmos that are far more stunning than anything Macy's can launch into the sky. These marvels celebrate the greatest kind of freedom, the one that allows the human mind to break free of this world and reach into the far depths of space and time. Here, then, a few of my favorite celestial pyrotechnics, many of them not yet widely seen. (If you enjoy this collection you can follow me on Twitter, where I pass along new science images all the time as they come in: @coreyspowell) It seems natural to start things off with a bang, and few things make a bigger bang than a supernova explosion. This is Cassiopeia A, the remains of a massive star that blew itself to bits 340 years ago (from our perspective). Strangely, nobody on Earth saw the event, perhaps because the star was thickly shrouded in dust. This image is taken in X-rays by the Chandra Observatory; there's a cool 3D visualization here.
As the remains of a supernova expand and diffuse, they produce different shapes and colors--just like fireworks here on Earth. The Pencil Nebula is one small part of a huge cloud created by another supernova, one that detonated 11,000 years ago. The image is taken in visible light at the European Southern Observatory, though the color are too subtle to be seen directly by the human eye.
Not all of the explosive activity takes place in the distant regions of space. This hot display of magnetic eruptions took place on our own sun, as seen by the Solar Dynamics Observatory. Notice that mysterious black round thing at lower right? That's the moon, moving in for an eclipse.
When the sun dies, about 7 billion years from now, it will put on an even more spectacular show. First it will swell up into a red giant; then it will cast off its outer layers, producing a beautiful gas cloud known as a planetary nebula. (Oh yeah, any life here will be destroyed in the process. Sorry.) The result could be a dramatic tantrum like the Helix Nebula, seen here in a composite infrared and ultraviolet image.
Or the sun might fade away in a delicate bubble. I especially love this image of Abell 33 because it reminds me of the concussion flash at the end of each firework display.
The gas clouds where stars are born have their own spectacular, firework quality. I recently discovered this incredible, fiery infrared image of the Rosette Nebula, created by zeroing in on a specific color of light emitted by hydrogen atoms.
Meanwhile, more fireworks in the aptly named Flame Nebula. Here, bright, hot stars are now forming 1,500 light years away in the constellation Orion. Intense radiation from the young stars lights up the surrounding gas. In the darker area at upper right there is a quiet bonus: look carefully and you will see a dim view of the famous Horsehead Nebula.
Bright, massive stars like the ones in Orion grow old fast. When they do, they go supernova, and what remains behind is a dense remnant of a star: a neutron star or an even more extreme black hole. This new X-ray image of the Whirlpool Galaxy sparkles with hundreds of bright purple dots, each marking the location where a black hole is sucking up gas from a nearby companion star and pouring out intense radiation.
No discussion of celestial fireworks would be complete without looking at comets. The recent Comet ISON was a fizzle from the perspective of average viewers, but sky photographer extraordinaire Damian Peach created a time series of the comet that looks kind of like...bombs bursting in air.
As with any good firework display, I figured this tour should end with a bang, too. This image blew my mind when I saw it. It shows a brand new crater on Mars, created when an asteroid slammed into the planet--while NASA's Mars Reconnaissance Orbiter was circling overhead! The 100-foot-wide gouge is a prominent reminder that cosmic fireworks don't only go up. They also can come down, catastrophically.