Scientists have finally confirmed something they had doubted, that Mars does occasionally emit puffs of methane into its atmosphere. That doesn’t necessarily mean what you presume it means, that the Red Planet is or once was home to alien cows or other forms of life. But it could.

Most of the methane on Earth is pumped out by microbes and other living creatures — most notoriously cows, which emit vast clouds of the greenhouse gas (though largely by burps, contrary to popular lore). So while sniffing methane may not be so thrilling on Earth, discovering that Mars is burping up the stuff — following confirmation that there is water below its rusty surface — fits a critical piece in a most intriguing puzzle.

Searching for life on Mars, or getting there, has obsessed earthlings ever since telescopes enabled them to spy on the neighboring globe. The passion persists. The methane report last week , from scientists working for the European Space Agency’s Mars Express orbiter, was followed by a statement from the NASA administrator, Jim Bridenstine, that the agency hopes to send astronauts to Mars by 2033. One way or another, the rusty dot of twilight is getting awfully lively.

The notion of Martian life gained popularity and respectability when Percival Lowell, a well-regarded scientist who founded the Lowell Observatory in Arizona, spent 15 years gazing at Mars at the close of the 19th century and came up with detailed maps of canals and oases, positing that they had been built by a civilization desperately tapping its last source of water as the planet dried up. That helped spur a rich Martian sci-fi literature, including such classics as C.S. Lewis’s “Out of the Silent Planet,” in which a dying Mars is populated by intelligent species that choose to become extinct rather than invade Earth.