Although similar in size to Earth, the planet-next-door Venus is typically perceived as a hellish inferno of caustic clouds, crushing pressures and kiln-like temperatures. And while those are indeed all very much the case, Venus has recently been found to have a cooler side too… although it’s 125 km (77 miles) up in its atmosphere.

In a new analysis based on five years of observations using ESA’s Venus Express, scientists have uncovered a very chilly layer at temperatures of around –175ºC in the atmosphere 125 km above the planet’s surface.

The curious cold layer is far frostier than any part of Earth’s atmosphere, for example, despite Venus being much closer to the Sun.

The discovery was made by watching as light from the Sun filtered through the atmosphere to reveal the concentration of carbon dioxide gas molecules at various altitudes along the terminator – the dividing line between the day and night sides of the planet.

“It is special, as we do not see a similar temperature profile along the terminator in the atmospheres of Earth or Mars, which have different chemical compositions and temperature conditions.”
– Håkan Svedhem, Venus Express project scientist

Armed with information about the concentration of carbon dioxide and combined with data on atmospheric pressure at each height, scientists could then calculate the corresponding temperatures.

“Since the temperature at some heights dips below the freezing temperature of carbon dioxide, we suspect that carbon dioxide ice might form there,” says Arnaud Mahieux of the Belgian Institute for Space Aeronomy and lead author of the paper reporting the results in the Journal of Geophysical Research.

Imagine… snow on Venus! Heat Miser definitely isn’t going to like that.

Read more on the ESA site here.