What's New?

Bad Astronomy

BA Blog
Q & BA
Bulletin Board

Bitesize Astronomy
Bad Astro Store
Mad Science
Fun Stuff
Site Info

Search the site
Powered by Google

- Universe Today
- The Nine Planets
- Mystery Investigators
- Slacker Astronomy
- Skepticality

Buy My Stuff
Bad Astronomy at
Keep Bad Astronomy close to your heart, and help make me filthy rich. Hey, it's either this or one of those really irritating PayPal donation buttons here.

The Making of "Under Alien Skies"

The January 2003 issue of Astronomy magazine has a feature I wrote called "Under Alien Skies". It's a big article; in fact, it's the cover feature. When I write an article, the process normally goes from idea to final product pretty quickly, usually in a few weeks or so. "Skies" took two years, and there were some weird twists and turns along the way. The story of how the article came to be might be of interest to some of you. It involves some astronomy, some personal aspects and a few surprises, especially for me.

I don't really remember how I came up with the idea for the article. The premise is to describe, as accurately as possible given current astronomical knowledge, what the night sky would look like from different locations in the Universe. We are used to seeing things from our warm planet a hundred and fifty million kilometers from our G type Sun, which in turn is halfway to the edge of the Milky Way Galaxy. But things would look mighty different from, say, the core of a globular cluster, or a planet huddling close to its red dwarf sun. Who hasn't wondered what it would be like to watch the Orion Nebula rise in the night sky from a planet orbiting a star a light year from the heart of the gas cloud?

The idea wasn't really a new one, but I thought it would be fun to combine the real science with descriptive prose, and see how well I could convey the imagery. So I called the editors at Astronomy magazine.

At this point, I was a bit wary. I had published an article in Astronomy before; in fact, it was my first paid article ever ("A Full Moon in Every Plot", April 1998, about how astronomy is abused by Hollywood). I'll be honest: the editing was not exactly subtle. I was fairly proud of what I wrote, and the editor at the time pretty much destroyed it. A lot of my voice was taken out of the article, the flow was ruined, and in the end the article was shortened too much. It takes time to build up a story, and the final editing took away a lot of my point. I was especially unhappy because I asked specifically to keep one particular passage in, but in the end the editor removed it so that he could fit in a bigger picture of Luke Skywalker. Yes, you read that correctly. On top of all that, I was severely underpaid for the article. I was too naive to know better, and accepted a fee that was much les sthen what the article was worth.

So it was with trepidation that I called the magazine back. I found out, to my delight, that my original editor was no longer with the magazine. Woohoo! One big hurdle jumped. I talked to them about my idea, and mentioned how they could get fantastic artwork to illustrate it. We didn't discuss money so early on, but we did talk about possible topics. I was told to go ahead and write up an outline and send it in.

I had taken a lot of notes on different possible scenarios for the article. I studied the ring around Supernova 1987A for my PhD, and was pretty familiar with it. I had dreams of what it would be like to see it up close, and I knew that the real scene would surprise most people. The problem was, I knew I could never write a description of the sky near the supernova in under 3000 words, which was longer than the whole article could be! Sadly, I had to abandon that idea (though I may yet write it up some day; there are some astonishing images involved...).

I settled on the view from the core of a globular cluster, the view from nearby a red dwarf, and the view a light year out from the Orion Nebula. The editors at Astronomy agreed, and I sat down with a pencil, paper, and a calculator and began to work out the math.

I started with Orion. What would the Great Nebula look like from a light year away? I looked up some numbers, like the separation of the four bright stars called the Trapezium, located in the heart of the nebula. Then I worked out how far apart they would be in the sky. They wound up being close enough together so that you could see them all at once, which was a good sign; as bright as they are they would be a fantastic sight. Then I started working on the nebula.

I immediately ran into a problem. Although the nebula is bright enough to be seen by the unaided eye even from 1500 light years away, I quickly realized that from up close it would be invisible! This shocked me, but I knew I was right. The problem is that the gas is almost transparent, what astronomers call "optically thin". It glows because it is energized by the flood of ultraviolet light from the Trapezium stars.But since the nebula is transparent, we see light from every atom of it all at the same time; the light from atoms on the far side of the nebula comes right through the gas. That means that the light we see is all the light there is from the nebula.

To us, far away, the nebula is bright because it's small. But if we get closer, it appears bigger, of course. But the total light doesn't change! As it gets bigger, the light from every square degree of it drops. It's like having a bucket full of water. When the water's in the bucket, it's deep. But if I dump the water into the floor, the depth drops to a tiny fraction of what it was. The same goes for the nebula. As it spreads out in the sky, the light from it thins. From Earth, the nebula covers about 3/4 of a square degree. From a light year away, the nebula would fill the sky, 20,000 square degrees. That reduces the light by a factor of about 30,000! From a light year away, the nebula is practically invisible!

Poof! Gone were the visions of filaments and streamers, diffuse red and green gas filling the night sky. I was shocked, then depressed. There went a third of my article! Well, I still had the globular cluster though.

Or so I thought. I started reading papers on stellar populations of globulars, and got even more depressed. I figured that the small core of a globular filled with giant stars would make the night sky a vast treasure chest of glittering jewels. But according to the paper I read, the stars weren't all that bright. There would be a very few bright ones, but most were too faint to be anything special. Yegads! My article was falling apart!

Reluctantly, I called the magazine back. I told them that according to my calculations, alien skies were... boring. The article wouldn't be anything like what I was hoping. I withdrew the proposal. They were unhappy too, but understood. What could anyone do?

Flash forward about a year. I was attending a meeting at the Astronomical Society of the Pacific in St. Paul, Minnesota (quite a ways from the Pacific, come to think of it). I was there to do a teacher workshop to demonstrate some educational activities developed by my group at Sonoma State University. As it happens, Dave Eicher, the editor from Astronomy was there. We chatted for a while, and then he invited me out to dinner at a local Japanese restaurant. I accepted, and then he mentioned that Jeff Hester would be coming along.

Dr. Hester is an observational astronomer, and his biggest claim to fame is that he was the team leader of the people who took the Eagle Nebula Hubble image. It is not too much to say that this picture revolutionized the way the general public saw astronomy. So duh, I was eager to sit with him and chat.

He turned out to be nothing at all like I expected. A huge man, he hails from Oklahoma and has a booming voice, and an even bigger laugh. We had a great time together. Every time he laughed, people in the restaurant would turn to look to see what was going on. Needless to say, I tried to make him laugh a lot.

Conversation turned to writing, and I mentioned to Dave that it was too bad about my Alien Skies article. Jeff asked about it, and I told him my tale of woe with the Orion Nebula, and how the light would get spread out so much. " That ain't right", he said to me. "The light from the thin gas would get spread out, but there are narrow shocked filaments all through the nebula. Those are small, and they'd still be bright.".

"So, " I replied, "the sky would be filled with a web of ghostly green tendrils?" He nodded. "Yep."

I turned to Dave Eicher. He looked at me, and we both nodded. "You're back on, " he said.

And so the article was reborn.

Still the globular had me stumped. I called my friend Wayne Landsman, who is an expert on globulars. To my delight, he told me I was stupid. Well, not really, but in essence he did: I had misread the article on globular clusters. The authors had lumped stars together in big bins, which averaged out their brightnesses. The brightest stars were thus averaged down, and in fact the sky would still be filled with luminous stars. Woohoo again!

When Dave and I talked money, the last woohoo! was shouted: they would pay me a far more reasonable fee for this article. I was happy, because I knew I'd earn it: this still wasn't going to be easy.

Little did I know. The word limit was set to 2500, which means each scene got 800 words; barely enough to make the point. I'd have to be frugal with my writing. As you can see from reading this, that isn't so easy for me. I'm chatty. Also, Dave told me they got Lynette Cook to do the artwork. Lynette is one of the world's foremost space artists; her work is hanging in the California Academy of Sciences, to name one place. Yikes! The pressure was on. My writing had to match her art.

Still, I like a writing challenge. I hunkered down and got to work. The Orion Nebula section came out quickly. I had to edit it down several times, but I got the gist of it. The sky would be dark, even a light year from the brightest nebula in the Earth's sky. But the filaments of gas, compressed by the stellar winds of the Trapezium stars, would glow green, criss-crossing the sky with eerie tentacles.

The globular cluster section was a bit rocky. No two globulars are exactly alike. Depending on, for example, the abundance of elements in the stars, some clusters have most red giants, some have blue, and some have multiple colors. There was no way I could describe this in 800 words, so I decided to just go with red stars, punctuated with a few blue giants. While this doesn't describe every globular, it had to do.

The red dwarf part, surprisingly, took the most math. I had to calculate the star's luminosity, and how far away a planet would be to have Earthlike conditions. I also had to find out how long its "year" was, and several other factors. Once I had those, that sections was easy.

I also had several phone conversations with Lynette, who it turns out lives not too far from me. We talked over what I would write, and what the skies would be like from these alien venues. During the next few weeks she sent me rough drafts, which we talked over: tweak this, de-emphasize that. Eventually the artwork took shape and the end products were lovely. I especially like the red dwarf star; she put in a double row of starspots and several flares; we had discussed how red dwarfs are commonly magnetically active and can have huge flares. The two rows of spots was her idea; she based this on our own Sun, which has more sunspots at higher latitudes due to the interaction of the Sun's magnetic field with the hot plasma making up its atmosphere.

Finally, I had a finished product. But I was worried; as the Bad Astronomer, I have to make sure as best I can that what I wrote was accurate. If I made an error, readers would flood me with email, and would never let me live it down! So I called Jeff Hester and Wayne Landsman, and asked if they would proof the articles. They both agreed.

Wayne felt that the globular section was accurate enough, given the limited conditions of the article. I also let him look at Lynette's artwork, and he was surprised! So many red stars... he said that he knew intellectually that this was accurate (if the cluster in question had only red stars with a few blue) but it was something else to actually see it. I was pleased; surprise is what I was aiming for in the article.

Then, disaster. Jeff Hester called back... and said everything I wrote about the Orion Nebula was wrong. Gulp! He said it would be accurate for a nebula that is just rarified gas, but the Orion Nebula is far more than that. It's actually part of a much larger thick molecular cloud. This cold cloud of gas and dust is completely opaque to visible light. The Trapezium stars formed in it, and they are so hot that soon after they switched on, their heat and UV light started carving a cavity in the cloud. They were near the edge of the cloud, and eventually ate their way out to the edge. The cloud blows out from there, allowing us to see in.

But those stars also illuminate the thick gas in the molecular cloud. Since this gas is thick, from up close it would still be bright! Aiiiie! My entire article was wrong! And it was only a couple of weeks before the deadline!

Thinking fast, I asked him: what if we were inside the cavity, looking back toward the Earth? The thick gas would be behind us, out of sight. We would still be looking through thin gas, ribbed with the filaments.

Jeff thought about it for a moment, and said "Yeah, that sounds right".


The article wasn't a total loss. I simply rewrote the intro, putting my mythical planet on the other side of the Trapezium, and switched the viewpoint to looking back toward Earth. From there, the bulk of what I wrote was accurate.

With that, I submitted the article. I thanked Jeff and Wayne in the author's bio at the end of the article, making sure that they got credit for their help, but disowning them from any other dumb mistakes I might have made.

And that's that. Dave and the staff at Astronomy put Lynette's globular cluster image on the cover of the magazine, and I finally got my feature.

It may not end here; I have lots more ideas for other Alien Skies. Supernova 1987A is one, the view near the core of the Milky Way is another. How about floating 100,000 light years straight up out of the Galaxy? Or near a black hole consuming its blue giant companion? Or two neutron stars, orbiting each other madly, velocities near the speed of light, when suddenly, bang, they coalesce? If the article gets some attention, they may want more.

There are a still lot of alien vistas out there. I just need to write about them.

©2008 Phil Plait. All Rights Reserved.

This page last modified