Today is the Winter Solstice - the day the darkness wins.

A couple of weeks ago, I was watching the new Star Wars series "The Skeleton Crew." There's a scene where they land on a moon and walk to a settlement. The gravity is the same as Earth's, and the mostly humanoid characters don't wear spacesuits of any kind. This is all very Star Wars - I've always maintained that it's more fantasy set in space than science fiction, so they don’t really need to be super scientifically accurate. They represent some things as realistic, though mostly for artistic reasons. For instance, as they walk across the surface, the planet that the moon encircles is rising in the background. A hauntingly blue gas giant.

It's very evocative imagery, and I may have been slightly inebriated while watching it because I then had a stoner thought, or more like a simple sophomoric question: why is the planet lit up but the moon is dark?

This immediately reminded me of a viral TikTok I saw a while back where a guy pointed his camera at the waxing moon and said something like "wow, it's crazy that the Earth is casting that shadow on the moon, and yet the Sun is over there. Give me a break, Mr. Scientists." (I tried to find it so I could link it here, but sifting through TikTok is roughly the same thing as wading through sewage).

Obviously, this guy is an idiot. When the Moon is waxing, or waning for that matter, it's dark not because the Earth is casting a shadow on it. In fact, that only happens during an Eclipse - it's literally what a lunar eclipse is. I feel like this is pretty common knowledge, but I'm also at a point where my faith in humanity is at an all time low so who knows what the proletariat think is going on in the sky...

I'm an idiot too, have no fear.

My stoner shower thought started an internal inquiry. Obviously, the reason why the planet is lit up in the show is the same reason our actual Moon is lit up when it waxes, which - by definition - happens every month. The Sun is so far away that it appears at a perspective point of infinity, which means that the light rays cast in straight parallel lines to both the Moon and the Earth. This, along with the dome-like lens distortion of the Earth's atmosphere creates the illusion that the light is hitting the Moon and the Earth differently.

But more simply than that, there's only one Sun. It's casting light and hitting only one side of the Moon. It's not the Earth's shadow, it's just night time on the other side of the moon, the same way it's night time on the other side of the Earth - or any planet or any moon in our solar system. The light is only coming from one direction.

Unfortunately for me, and now for you, dear reader, this was not the end of it…

The planet is lit up because it's catching the light from the local Star, but the moon that the characters were on had revolved past sunset and was now in night. This made sense about ten seconds after I had the initial thought, but then another question - an ancient question - came bursting into my brain.

Why don't the other stars light up the moon?

At the time, I had no idea how profound this question was. If there are a sky full of stars and they're all emitting epic amounts of light, and light travels faster than anything and it never stops, and there are literally countless stars - why isn't everything lit up all the time? Why is there night at all?

Well, turns out that this was quite the quandary for physicists for hundreds of years too. According to known laws of physics, this is exactly what should happen: the light from distant stars should illuminate the night sky, like second suns.

We're pretty far away from the Sun and yet it's blinding during the day. Sure the other stars are far further, but if light travels in straight lines and never stops, then shouldn't it be blinding to look at them too?

There is a known mathematical law called the Inverse Square Law of Light. This shows that light in a vacuum will fade at 1 over the distance squared. So it makes sense that the light from stars would be faded, sure, but aren't there trillions of them out there? Are they not still just as bright as the Sun if not more so?

The first person in recorded history to ever think deeply about this was an English mathematician in the 1500’s named Thomas Digges. He called it the "dark night sky paradox." It's a paradox because, especially at the time, it was thought that the Universe was infinite and static, and that the Earth was at it's center - all the more reason why the night sky should be ablaze with light.

For three hundred more years the paradox stood. In the meantime, other great scientists took note of the issue. Johannes Kepler who later got a NASA planet hunting satellite named after him, and Edmond Halley who got a comet. None of them could solve the mystery though.

Then in 1823, a German amateur astronomer named Heinrich Olbers suggested that the reason why the light fades from distant stars was that there was a cosmic veil of dust obscuring everything in the night sky. This turned out to be false for the most part. There is a veil of sorts in the form of nebulae, but they're just as patchy as stars themselves and, we now know, that they actually illuminate rather than obscure.

Olbers' main conjecture was that if the Universe is infinite and full of stars then every point in space - every sightline from Earth should land on a star; and since there's no known mechanism that would cause the light to lose any brightness despite being so far away, every star should be as bright as the Sun.

The dark night sky paradox was not truly solved until the 1920s when an American astronomer named Edwin Hubble - maybe you've heard of him - took a gander at it. Hubble was interested in the small blobs astronomers often saw when gazing into space. They weren't stars, and they were too far away to be local nebulae. Hubble had a hunch...

They were other galaxies.

Some were just as big as our own, some were even larger, and what was wild was that they appeared to be moving away from us at alarming speeds. This proved once and for all that the Universe was not static, nor was it finite. Everything appeared to be moving away from a central point. So in addition to the light being faded due to the inverse square law, the light was also being stretched and pulled away from us as well.

The fabric of space itself was diluting the light.

Around this same time there was this guy named Albert Einstein - maybe you've heard of him too - who showed that light does not travel infinitely fast. It has a speed limit: the famous E equals MC squared. C, the constant, is the speed of light, about 300,000 kilometers per second. It's not so much that light cannot travel faster - it's that the laws of space and time, the literal fabric of the Universe, doesn't allow anything to move more quickly than that. It's a cosmic speed limit and photons just happen to be the smallest, lightest possible particle and therefore the fastest.

However, space itself is not bound by this law. Space is not a particle, it isn't a substance, it's nothingness, and nothingness can expand and grow far faster than light. Despite our best efforts, the darkness outpaces the light…

I doubt the creators of the Skeleton Crew were thinking about this at all. They were just trying to come up with a cool set piece for their show. Still, inherent to the theme of Star Wars generally, the light is a precious thing. There's far more darkness and it's more powerful than the light could ever dream.

Some good news: on Christmas Day, 2021, NASA launched the James Webb telescope into the void, almost exactly three years ago. The key difference between the Hubble and the Webb, other than decades of technological development, is that the Webb uses infrared sensors rather than visible and ultraviolet. Infrared is more commonly known as heat to we humans, but it’s actually another form of light in terms of physics.

In these spectra, the Universe really is as wildly ablaze just as Olbers and Digges thought it should be.

Page 64 of FLOLAS is almost done. Ironically, I’m busy adding more darkness to it.

Stay in the light my friends 🙏