The first known interstellar visitor to the Solar System

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Cosmic Driftwood

What a floating rock can tell us about life in the rest of the universe

Panel from “Cosmic Driftwood”. [Credit: Maki Naro (art) and moi (words)]

Last October, we had the first known interstellar visitor to the Solar System: an asteroid named ʻOumuamua. In our latest comic for The Nib, Maki Naro and I explain how we know the building-sized rock isn’t from around here, what we know about it, and what it might tell us about life elsewhere in the galaxy.

If we could only build one huge observatory….

[ This blog is dedicated to tracking my most recent publications. Subscribe to the feed to keep up with all the science stories I write! ]

Q: Suppose we can only build one big telescope. Should we look for life among the stars or the origins of the universe?

I participated in an experts’ roundtable for Aeon Magazine, in which we were asked (more or less facetiously) what single project we would support to settle either questions about the very early universe or the existence of life elsewhere in the cosmos. Of course my real answer is that we should support all the science, because discovery isn’t about looking for one thing, but seeing what new things we can find. Throwing all our money at one big project might accomplish something, but it’s a bad way to do science. But anyway, taking the question for what it is — a fun exercise in wishing — here’s my answer, along with thoughts from Ross Andersen and Caleb Scharf.

When our Sun runs out of nuclear fuel, it will shed its outer layers, while what’s left of the core will remain as a white dwarf: an object the size of Earth, but far more massive. During the final stages of the Sun’s life, Earth is likely to perish as a habitable world, but that’s not necessarily the case for every planet orbiting a Sunlike star. That’s the basis of a new paper, which posited that white dwarfs may even provide the best hope for detecting extraterrestrial life.

The advantages of these systems would be manifold: a white dwarf is much smaller than a star, so if a planet passes between it and us, far more light is blocked. And Avi Loeb and Dan Maoz proposed that at least some signs of life might have survived the deaths of these stars. The light emitted by the white dwarf could highlight any oxygen in the exoplanet’s atmosphere, which would be seen as a strong hint of life. [Read more…]

Living planets in a stellar graveyard