An international team of researchers says they have detected phosphine gas in the clouds of Venus, a possible sign of life on the planet.
Scientists from Britain's Cardiff University, Japan's Kyoto Sangyo University and others published their findings in the British science journal Nature Astronomy on Monday.
The team detected minute amounts of the gas, made of hydrogen and phosphorus atoms, about 60 kilometers above Venus' surface using radio telescopes in Hawaii and Chile.
Phosphine is generated by a chemical reaction on some planets, but on Earth, it's produced by microbes.
The team said the phosphine in the Venusian atmosphere could have come from an unknown chemical reaction or life activity.
They explained that the chemical would be dissolved as soon as it's created in the planet's environment, and that volcanic activity or lightning would not produce the amount detected.
Venus, which is Earth's closest planetary neighbor, is believed to be inhospitable to life. This is because its proximity to the sun and its thick layer of carbon dioxide keep its surface temperature very high, at almost 500 degrees Celsius.
But some scientists are hoping to find signs of life dozens of kilometers above the planet's surface, where the temperatures and pressure are lower.
The research team said the finding is not proof that life exists on Venus.
But the discovery is already generating excitement.
US space agency NASA's Administrator Jim Bridenstine posted on Twitter that the finding is "the most significant development yet in building the case for life off Earth."