NASA’s Parker Solar Probe has taken unprecedented visible-light images of Venus’s nightside, revealing surface features that would otherwise be obscured by clouds.
The new views were captured when the spacecraft made its fourth pass of Venus in 2021. Parker is using the planet’s gravity to get closer to its primary target, the Sun, but mission specialists have found a surprising use for the probe as a tool for studying Venus.
The onboard Wide-field Imager for Parker Solar Probe, or WISPR, imaged the entire nightside of Venus in wavelengths of the visible spectrum and near-infrared, according to a NASA release. The fun thing about all of this is that WISPR is designed to capture images of the solar corona — the area of plasma around the Sun — but the Parker team has learned, much to their surprise, that it’s also capable of gazing through Venus’s thick atmosphere.
“Venus is the third brightest thing in the sky, but until recently we have not had much information on what the surface looked like because our view of it is blocked by a thick atmosphere,” Brian Wood, a research physicist with the U.S. Naval Research Laboratory, said in the statement. “Now, we finally are seeing the surface in visible wavelengths for the first time from space.”
The images are allowing scientists to discern surface features such as continental expanses, plains, and plateaus. The new data will provide valuable information about the planet’s geology and history, NASA said.
The longest wavelengths of visible light can penetrate Venus’s clouds, which WISPR detects as a faint glow on the planet’s nightside (when the wavelengths aren’t crowded out by the Sun). Light areas in the images are warmer, while dark areas are cooler. The “surface of Venus, even on the nightside, is about 860 degrees,” said Wood. “It’s so hot that the rocky surface of Venus is visibly glowing, like a piece of iron pulled from a forge.”
That WISPR was capable of this feat became apparent during Parker’s third flyby of Venus in July 2020. The partial view of Venus took the team by surprise, so they ramped things up for the next encounter. Parker’s fourth trip around Venus lined up perfectly such that the probe was able to capture the planet’s entire nightside as it zipped past.
The team identified surface features by comparing the new images to pre-existing topographical maps created with radar, including radar views captured during NASA’s Magellan mission of the 1990s. Features visible in the new images include the continental region Aphrodite Terra, the Tellus Regio plateau, and the Aino Planitia plains. The team even spotted a halo around Venus, the result of oxygen atoms hitting the atmosphere.
The new data will be of interest to other scientists, as it could be used to detect minerals on the surface, since different minerals glow at specific wavelengths. It could also shed new light on the history of the planet and how volcanic activity may have contributed to its evolution and thick atmosphere.