Ethan Siegel

The Universe is: Expanding, cooling, and dark. It starts with a bang! #Cosmology Science writer, astrophysicist, science communicator & NASA columnist.

The Physics of the Death Star

How to destroy an Alderaan-sized planet.

“What’s that star?
It’s the Death Star.
What does it do?
It does Death. It does Death

Ask Ethan #77: Humans in the vacuum of space

Will you explode, freeze, or boil? Advice on how to maximize your life.

“A vacuum is a hell of a lot better than some

Throwback Thursday: Earth’s second moon?

Another world orbits the Sun once a year at the same distance as our planet.

“The moon was like this awesome, romantic…

Death is not the end

Lessons from the Universe whenever a light goes out.

“End? No, the journey doesn’t end here. Death is just another path, one that we all

Publications edited by Ethan Siegel

The Universe is out there, waiting for you to discover it.

Mostly Mute Monday: Crater chains of the Moon

Do craters only come in isolation? These images will make you think again!

“These spots have never been observed by…

Weekend Diversion: Bubbles on Ice

Amazing, fun and beautiful. So long as the cold doesn’t bother you, anyway.

“The only frozen heart around here is yours.” -Anna…

Ask Ethan #76: The very early Universe

What happened when things were hot enough to spontaneously create matter and antimatter?

“It followed from the special theory

Throwback Thursday: The science of bottomless pits

What would happen if you dove into a hole straight through the Earth?

“Where you used to be, there is a hole in…

Don’t trust your theoretical “proof”

Theorems are gold in math. But in physics? The Universe will surprise you.

“What we need is more people who specialize in the

Observing Night

All you need are clear skies, a telescope, and a plan. Make it a great one.

“For my confirmation, I didn’t get a watch and my first pair of long

Mostly Mute Monday: A Comet Comes Alive!

As comets approach near the Sun, they develop tails. Watch it happen.

“In the year 1456 … a Comet was seen passing