The Big Idea: Philip Plait

Posted on April 18, 2023    Posted by John Scalzi      7 Comments

Here on Earth, we have a pretty decent view of the universe (when it’s not cloudy, or when there’s light pollution, or the sun is out, or…). But the universe looks different depending on where in you stand. Or so Dr. Philip Plait suggests, in his new book, Under Alien Skies.

PHILIP PLAIT:

As someone who quite often speaks to the public about astronomy, I get a lot of cosmic questions from people — honestly, mostly about black holes and aliens. But if I’m talking about specific astronomical objects, showing dazzling and mind-vaporizing Hubble or JWST images of nebulae or star clusters in a talk, for example, the question I hear the most generally falls under the category of, “Is this what it would look like if you were actually there?”

Good question, right? And while simple to ask, it’s deceptively hard to answer. The truth is, “No. Well, maybe. Sometimes. But not really. Kinda.” Worse, the more detail you try to give the harder this gets.

Telescopes use filters and digital cameras that sense light in very different ways than our eyes do, so right away the photos perforce aren’t how we’d see something if we were floating in space above it or in it or on it. Sometimes just the fact that we’re viewing them from far away changes what we see.

And, most importantly I think, while telescopes show us amazing views of these distant vistas, seeing a photo on a screen is isolated, an almost completely removed experience from being there, seeing and feeling and sometimes even hearing it for ourselves.

What would it be like, to stand under alien skies?

After answering this question over and again, it dawned on me that it would be a good topic for an article, so I wrote one for Astronomy magazine, published in 2003. In it I described what you would see if you were standing on a planet inside the Orion nebula, or orbiting a red dwarf, or inside a magnificent globular cluster — hundreds of thousands of stars all packed into a ball about a hundred light-years wide.

I let my imagination soar, and described this all in a first-person narrative, more of a series of short stories than an expositional science piece. The article was received well, and for me the experience was transcendent. I got to imagine myself standing on these alien worlds, using science to inform the descriptions, and letting my own wonder and joy flow through the words.

And that was only for three astronomical locales. What would you see near a black hole? Or standing on a planet orbiting binary stars? Or sailing just above the rings of Saturn, the sparkling chunks of ice flying past, forming bizarre and literally other-worldly patterns?

I knew there was a book in there. And it only took me twenty more years to get aroud to writing it.

Under Alien Skies explores these strange, new worlds. Each chapter starts with a short vignette, a scifi (but strictly sci-based) scene giving you the experience of visiting some cosmic destination — the moon, Mars, a rubble pile asteroid, a planet orbiting a nearby red dwarf that has seven Earth-sized worlds… and then digging into the science of why they are what they are.

Some of it was easy to write — as a degreed astronomer with a zillion hours of experience behind an eyepiece I have some familiarity with astronomical objects, so talking about the conditions in and around and on them, what you’d actually see from them, wasn’t too hard. But as I looked into details things got weird. Does the Earth really hang motionless in the sky from the Moon? (no) Would a dust storm really blow you down on Mars, lightning flashes and tornadoes destroying everything in their path? (no, but maybe a little) Was the twin suns-set Luke Skywalker watched on Tatooine accurate? (yes!) What would you see as you fell into a black hole? (your death, pretty much, but lots of cool stuff on the way down)

And the math. Oh god, the math. So much math. You won’t see any of it in the book, but you’ll see the results: A sky full of swollen planets hanging down over you, streamers of excited gas filigreeing your view inside a nebula, multiple shadows cast by eye-squintingly bright stars inside a cluster. At one point I had to do about four pages of algebra just to describe what would happen if your planet orbits binary stars, and one eclipses the other. How much would the temperature drop? Hint: Keep a sweater handy. Maybe. The physics is a little complicated.

The whole point of writing this book wasn’t to simply describe these wonders, but to get you to experience them. Standing on another planet you’d weigh a different amount; walking would take practice. Landing on an asteroid is tricky; you’re more likely to sink into it than stand on it. The best way to tour Saturn? A pressurized (and heated!) gondola under an immense hydrogen dirigible.

The Big Idea here (if I may) was not to blast you with a firehose of science and descriptions, but to take you by the hand and show you what these places are like.

And they are places. They actually exist; they’re not just dots in a telescope or a wiggle in a graph or a fuzzy blob in the eyepiece. These are alien worlds, as real and diverse and extraordinary as our own, and we can know them through science. While we can’t yet visit them, we can certainly imagine ourselves there.

In Under Alien Skies I’ll take you there as best I can.

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