In Reality, Nebulae Offer No Place for Spaceships to Hide

In the Battlestar: Galactica universe, nebulas are a nifty spot to hide from the Cylons that are plotting to kill humanity. There’s just one problem with the hypothesis, though — these diffuse areas of gas in our universe are actually very faint, even if you get close up. Probably too faint for a hiding spot.

Prequel Battlestar Galactica: Blood and Chrome (released on DVD this week) shows the young William Adama flying around the universe with pretty nebulas in the background. That’s not anywhere near the truth, Harvard astronomer Peter Williams told Universe Today.

In an e-mail, Williams explained that bright nebulas are a common misperception seen in Star Wars, Star Trek and a host of other sci-fi series.

The big issue is that nebulae are just too faint for the human eye to see. And while it’s tempting to think that they’d look brighter from up close, in fact this isn’t actually true — they actually look just as bright from any distance! This is a law of optics, known in the jargon as the “conservation of surface brightness”. The key is that there are two competing effects in play. Imagine that you can see a nebula that’s, say, the size of the full moon.

Yes, if you get closer, your eye will receive more total power from the nebula. But the nebula will also look bigger, so that energy will be spread out over a larger visual area (technically: “solid angle”). The physics tells you that the power per solid angle in fact stays exactly the same, and this quantity is precisely the “brightness” of an object. So if nebula are too faint for to see from Earth with the naked eye — and they are — getting up close and personal doesn’t help any.

Those bright colors surrounding Battlestar's ships are not actually what you would see if nestled in a nebula, according to  Harvard astronomer. Credit: Battlestar Galactica/SciFi (screencap)
The opening sequence in Battlestar: Galactica shows the ships hiding in a bright nebula. Credit: Battlestar Galactica/SciFi (screencap)

Further, Williams, explains, the bright colors we’re used to seeing in Hubble Space Telescope images are just an approximation of what a nebula actually looks like.

Reproduced images of nebulae don’t portray their colors accurately. As you may know, some astronomical images use “false color” to represent wavelengths of light that humans can’t even see. This does happen with images of nebulae, but nebulae really are colorful, and many nebula images try to reproduce those colors faithfully. No current reproduction, however, can be truly accurate.

The Crab Nebula. Image credit: Hubble
The Crab Nebula. Image credit: NASA/Hubble Space Telescope.

The problem is that the colorful nebular emission comes from reactions that produce light at a few, specific wavelengths; meanwhile, our inks and pixels emit over much broader wavelength ranges. We can mix these broad ranges in ways that approximate the narrow ones, but the results aren’t quite the same.

For an entertaining look at the science of nebulas, Williams recommends this entertaining video by astronomer Phil Plait, a long-time friend of Universe Today who is best known for his Bad Astronomy blog (now at Slate). “If you were inside [the nebula and looked down], you wouldn’t see it,” Plait says in this 2008 clip.

Guess it’s time to find another spot to hide.

Captains, Cylons and Wizard World Chicago

After years watching from the sidelines, I’m fast becoming a comic convention convert. It seems there is something at cons for every geek, whether you enjoy meeting celebrities, hearing illustrators talk about tricks of the trade, or browsing the show floor in search of posters, T-shirts and comic books.

This past weekend I briefly attended Chicago Comic Con Wizard World Convention, which typically draws tens of thousands of fans — including friends of the space genre, judging by the T-shirts surrounding me. I was there to line up for a brief photo op with three Star Trek captains (Kirk, Archer and Sisko), and I have to say my whole time there was a pleasant experience.

I’ve been to two other comic cons that were an organizational mess, with fans lining up for autographs and photo opportunities, waiting hours for late celebs. One con was so crowded that the fire marshall had to prevent people from coming in.

While I admittedly was at Wizard World at a slower time (Friday afternoon), the relaxed pace was a welcome change from other cons. Lineups were very short, allowing me time to have a quick chat with Dean Stockwell of Battlestar: Galactica fame. I also got a quick picture of him on my cell phone.

My favourite part of each con is looking at funny T-shirts and posters. Some of the jokes are rather obscure, but I usually can figure out what the space-related ones mean.

As for the Captains, they were there at the appointed hour. I had about 15 seconds for the photo op — just enough time to shake hands with Scott Bakula, agree with him that Chicago is a beautiful city, smile beside him and William Shatner and Avery Brooks, then scoot out of there to make way for the next person.

My goal is to meet all of the starring Star Trek captains. As of this con I’ve seen all but two. Janeway (Kate Mulgrew) actually was supposed to be at Wizard World, but had to back out due to another commitment. The other I’m looking for is the new Captain Kirk (Chris Pine). Guess I’ll be saving my money for next year.

All pictures by Elizabeth Howell.

Elizabeth Howell (M.Sc. Space Studies ’12) is a contributing editor for SpaceRef and award-winning space freelance journalist living in Ottawa, Canada. Her work has appeared in publications such as SPACE.com, Air & Space Smithsonian, Physics Today, the Globe and Mail, the Canadian Broadcasting Corp.,  CTV and the Ottawa Business Journal.