Hello, SFIA audio listeners. In this month's Nebula exclusive, Big Alien Theory,

we're asked at the reason alien civilizations might be rare is because most aliens are huge.

To hear it and every episode early and add free, plus hours of bonus content,

check out go.nebula.t.

And use my code, Isaac Arthur.

T'was the night before Christmas and all through the stars, not a creepier slash Isaac Arthur, and use my code, Isaac Arthur.

T'was the night before Christmas, and all through the stars, not a creature was stirring, at least not on Mars,

but deep in the void where dark matter flows, the next great discovery quietly grows.

Winter is one of the best periods for stargazing. The longer, clearer nights offer some the best celestial sights. As we look up the sky this type of year, we remind the universe

itself a grand and ancient gift, one still wrapped in mystery. Maybe Discovery, like Christmas,

doesn't come from a store. Maybe Discovery, perhaps, means a little bit more.

Every time we unwrap one of the cosmos's secrets, it feels like opening a present,

one that deepens our wonder but also our responsibility, because knowledge, like a true

gift, comes with care, for the worlds we explore, the minds we expand, and the civilizations

that might one day share that same awe.

And we have still got a lot of presence left to open.

There are entire galaxies of mysteries still hidden in the night sky, vast cosmic void

stretching hundreds of millions of light years across, where

matter seems to vanish without explanation. The great attractor, quietly tugging whole

galaxies across intergalactic space, is source still unseen. The three-eye atlas object,

an interstellar visitor whose origins defy easy explanation, and which exhibits strange behaviors.

Tabby's star, whose flickering light once made us wonder if alien megastructures might be casting shadows on its face.

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