Offhand, I can’t recall many stories where the characters pause to admire the night sky. Usually it only happens if there’s a specific purpose. If not, a writer may say the character is gazing at the stars, and leave it at that.

That’s perfectly fine. It also gives those of us who write an easy out: we don’t have to describe the night sky at a certain place and time.

If, however, it’s historical fiction, we must to tread carefully. If a story takes place in the fall of 1604, it would be impossible to miss a brilliant star in Ophiuchus. Today it’s known as Kepler’s Nova, and in October of that year it shone at its peak. Or, if a story set in May, 1066, doesn’t mention a comet, that’s likely to be noticed by more than astronomers. Halley’s Comet was observed that year, and seen as an ill omen in England. By the end of October, England’s King Harold would be dead, and William of Normandy well on his way to conquering the country. Noting the comet in a historical novel set in England of that year would be accurate, and excellent foreshadowing. We also have to be mindful of events like eclipses, both solar and lunar.

While not necessary in non-historical fiction, it can be a nice touch if done accurately. That’s not as difficult as it sounds. Today, we have access to astronomy programs, some free, that can give us an idea of what the night sky looked like at a certain place and time.

Place is as just as important as time. In a scene I’ll have to rewrite, a character looks up at the night sky and sees Leo almost overhead. I’d taken a star chart and made an “Eh, close enough,” adjustment for the Precession of Equinoxes, and let it rip. Bad idea. A quick check with an open source astronomy program showed I was wrong. What happened? The character was at a different latitude than for the chart, and it changed things a small, but significant, bit. And that’s why characters tend to “gaze up at the stars” and not “He traced the path of Orion in his endless battle with Taurus, the giant hunter’s faithful hounds trailing behind.” That might be fine if it’s the winter evening sky, but not if it’s a couple of hours past sunset in August. If the character is at a high enough latitude, or there are mountains in the way, he may not see canis major and minor at all.

That “he gazed up at the stars” sounds better and better.

Of course, mentioning something specific in the night sky can add a pinch of spice to a story, if we’re careful not to overdo it. There’s a tendency among writers to say “I’ve suffered for my art and now the reader must as well.” We could describe the sky in excruciating detail, but what does that mean for the story? Too much can be the equivalent of adding too much spice to the stew; a little makes it delicious but a lot makes it inedible.

Something we should be aware of is the aforementioned Precession of Equinoxes. The earth sort of wobbles on its axis, and this has two effects. One is that the constellations we see in the sky slowly move in respect to the seasons. It’s not even a degree and a half very century, but it adds up over time. In the last 2,000 years, the constellations have shifted nearly 28 degrees. This means the constellations we see in the sky now during the spring equinox isn’t what Julius Caesar would have seen. It’s slid backward almost a full month since his time.

If we’re going to do a gloss of “He looked at the stars,” we don’t have to worry about it that much. But the earth’s wobble has another effect: It changes our north star. Right now it’s Polaris, but it wasn’t always so. If we’re in Medieval times, it pointed close enough to Polaris that the star was often used for navigation. But if our character is trying to find the north star in 3,000 BC, it’s going to be Thuban, a dim star in the constellation Draco. Polaris may have been a close enough to the earth’s northern axis to be called the north star in William Shakespeare’s day, when he has Julius Caesar referring to himself by that title, stating he is true fixed (unmoving). However, when the real Julius Caesar looked north, the stars would seem to revolve around a point between the tail of Draco and the Little Dipper.

We also have to remember that different peoples made different constellations, or called familiar constellations different names. Our Big Dipper has been called the Plow in England; the Great Wagon; in Germany; and the Bear by the ancient Greeks. The name of the stars themselves change according to place and time. Even the name Polaris, short for stella polaris, is only a few hundred years old.

Putting this all together, especially for historical fiction, can be daunting, but thanks to the internet, most of it is available with just a little searching. It’s possible to find everything from phases of the moon to eclipses to, well you name it. Then there’s astronomy programs, which, while they might not tell us everything about the night sky at a certain time in the past, can give us some idea. I happen to like Stellarium, one of many open source astronomy programs.

Maybe, though, we can save ourselves a lot of pain, particularly in pure fiction, by just having our characters look at the stars. But if we want to add a little more detail, we have to remember to do our homework.

Now, if you’ll excuse me, I have scene to rewrite.