Enlarge / A perspective view across Maat Mons on Venus, based on Magellan radar data. (credit: NASA/JPL)

Venus is almost the same size, mass and density as Earth. So it should be generating heat in its interior (by the decay of radioactive elements) at much the same rate as the Earth does. On Earth, one of the main ways in which this heat leaks out is via volcanic eruptions. During an average year, at least 50 volcanoes erupt.

But despite decades of looking, we’ve not seen clear signs of volcanic eruptions on Venus – until now. A new study by geophysicist Robert Herrick of the University of Alaska, Fairbanks, which he reported this week at the Lunar & Planetary Science Conference in Houston and published in the journal Science, has at last caught one of the planet’s volcanoes in the act.

It’s not straightforward to study Venus’s surface because it has a dense atmosphere including an unbroken cloud layer at a height of 45-65 km that is opaque to most wavelengths of radiation, including visible light. The only way to get a detailed view of the ground from above the clouds is by radar directed downward from an orbiting spacecraft.