The Economist explains

The significance of liquid water on Mars

There could be an ocean’s worth deep underground

Photograph: NASA

THE APPLICATION of Bayesian inversion to a range of lithologic parameters in an assessment of seismic data hardly seems the stuff of headlines. But when the seismic data you are assessing come from Mars, and when your reasoning suggests that the best explanation for them is liquid water in the pores between rocks, you have a story. There is little people thirst for more, when it comes to planetary science, than water on Mars. Why does the prospect provoke such excitement—and what does this new research add to the story?

More from The Economist explains

Who will lead Britain’s Conservative Party?

Here are the four candidates vying for the daunting job

When can parents be held responsible for their children’s crimes?

Mass shootings by young assailants are raising the question


Will the debate between Kamala Harris and Donald Trump matter?

Normally presidential match-ups hardly move the needle—but this is no ordinary year


What are the Murdochs fighting about in a secret Nevada court?

The outcome could shape the political orientation of the family’s media empire

The battle between drones and helicopters in Ukraine

Small cheap drones could pose a new threat to expensive Russian craft

A short history of political meddling with the Federal Reserve

Donald Trump’s attacks on the Fed are a throwback to the era before central-bank independence