Despite all the information we’ve discovered from our telescopes and outer space missions, there are still many puzzles to solve in our own solar system. Sometimes, it seems the more we learn, the more mysteries we uncover.
We’ve also observed radio emissions from the planet’s hot surface. When NASA’s Magellan spacecraft last visited Venus 20 years ago, we discovered two mysteries that have yet to be solved. First, the higher the elevation on Venus, the better (or “brighter”) the radio waves reflect off the surface. Something similar happens on Earth but with visible light.
That means we see cooler temperatures at higher altitudes. Think of how the warm surface of the Earth can transition to ice and snow on a mountaintop. That’s our brightening pattern in visible light.
The second mystery is that we get radio dark spots at the highest altitudes on the planet’s surface. For example, scientists saw lower radar reflections at 2,400-meter (8,000 ft) altitudes then a rapid brightening (or increase in radio reflections) as the elevations rose to 4,500 meters (14,750 ft). But by 4,700-meter (15,500 ft) elevations, they got many more black spots, sometimes numbering in the hundreds. Those places go radio black.