Nebulae. They generate some of the most exquisite space photos around. They come with some funny names, like the Horsehead Nebula, the Cat’s Paw Nebula, even the Fried Egg Nebula. They hang out around stars, hot and cold, young and old.
Lucky for us, some of the best instruments in the world for doing this kind of thing, like the European Southern Observatory’s VLT — it stands for Very Large Telescope — have been capturing these celestial inspirations for a while now. And we get to reap the benefit of that astronomical work. The slideshow above highlights 100 images (plus a few bonus shots) of nebulae, all from the ESO’s collection.
So what exactly are we looking at?
Nebulae are complicated, ESO’s Jeremy Walsh told Weather.com. At their most basic, they are clouds of gas. But, “you can get nebulae around young and around old stars,” he said. “Then you have to distinguish nebulae depending on how hot the star is.”
Let’s look first at the difference between nebulae around young and old stars. The former produce large, extensive gas clouds, whereas the latter generate those that are much smaller and more confined.
The Helix Nebula sits around an old star. “You can see the star in the middle. It looks rather faint and puny. That’s a star like our sun will be in 5 to 6 million years,” Walsh said. (View it in image #3 above. Blue and orange colors are visible, the blue being the hottest gas, is oxygen; the orange the cooler gas, from nitrogen.)
The heat of the star changes what colors the nebulae appear to us. “If the star is very hot — more than about 30,000 degrees — then it ionizes the gas. It knocks the electrons out of the atoms and the atoms get into an excited state, and they emit radiation,” noted Walsh. It’s not a whole spectrum of light but rather some specific colors, like green and red, he added.
Just one more thing: Space is filled with dust, tiny little particles produced by stars. When the dust builds up, it can sometimes obscure our view of nebulae, like with the Horsehead Nebula (#21 in the slideshow). Dust sits in the foreground so we see the horsehead in silhouette.
You should know, the colors in the images aren’t true to life. Some are taken with different filters. Others are composites of several photos placed together. Either way, they’re still apt to take your breath away. So go ahead, enjoy some mid-day star- (and gas-cloud-) gazing.
The ESO 3.6-meter telescope at La Silla observatory in Chile, during observations. (ESO/S. Brunier)