Venus’ atmosphere is rightfully famous for a combination of being stunningly hot and containing sulfuric acid. Those conditions, not surprisingly, have ensured that every bit of hardware we’ve sent through said atmosphere has had an extremely short lifespan.

But at least one of those pieces of hardware—the Soviet Union’s VeGa-2 probe—sent back some data that’s hard to explain, a hint of an unstable atmosphere. Now, a pair of scientists is suggesting that the oddity can be explained by an equally odd feature of the atmosphere: it’s a supercritical fluid where different chemicals partially separate at different altitudes.

The sulfuric acid and a surface temperature of 464 degrees Celsius, which is hot enough to melt lead, would seem to be more than sufficiently unusual for a planet. Yet Venus’ oddities don’t stop there. Its atmosphere is so dense and reflective that its surface gets less sunlight than the Earth does, even though Venus is closer to the Sun.