Venus glows like ‘iron pulled from a forge’ in new image

Beneath a thick cover of clouds, Venus is aglow.

The Parker Solar Probe mission, intended to study the sun, has revealed more about what lies beneath the thick atmosphere of Venus. The spacecraft captured its first visible light images of the planet’s surface during a 2021 flyby.

As Parker approached Venus in February 2021, it was able to capture the red thermal glow exuded by Venus created by heat coming from the planet’s surface.

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“The surface of Venus, even on the nightside, is about 860 degrees,” said lead study author Brian Wood, a physicist at the Naval Research Laboratory, in a statement. “It’s so hot that the rocky surface of Venus is visibly glowing, like a piece of iron pulled from a forge.”

The surface of Venus remains very much a mystery to scientists because it’s hidden beneath thick clouds that prevent it from being seen.

The Parker Solar Probe has an imager, called WISPR, that was able to peer beneath this hazy cover while imaging the entire nightside of Venus in visible light that humans can see, as well as near-infrared light, which is otherwise invisible to us. The name WISPR is short for Wide-field Imager for Parker Solar PRobe.

The spacecraft has used gravity assists from Venus, where the probe essentially swings itself around the planet, to get increasingly closer to the sun. During those flybys in July 2020 and February 2021, Parker kept its imager on and aimed it at the dark side of Venus.

Dark regions on Venus seen in this WISPR image correspond with dramatic geologic features on the surface.

The imager was designed to detect faint features in the solar wind that streams out from the sun. The newly releasedimages are part of a study that published Wednesday in the journal Geophysical Research Letters.

The images show that the Venusian surface exudes a faint glow, and features like plains, plateaus and continental regions can be distinguished. There is also a glowing halo of oxygen in the planet’s atmosphere called airglow, a type of light that also exists in Earth’s atmosphere.

“We’re thrilled with the science insights Parker Solar Probe has provided thus far,” said Nicola Fox, division director for the Heliophysics Division at NASA Headquarters, in a statement. “Parker continues to outperform our expectations, and we are excited that these novel observations taken during our gravity assist maneuver can help advance Venus research in unexpected ways.”

When flying past Venus in July 2020, Parker Solar Probe's WISPR instrument, short for Wide-field Imager for Parker Solar Probe, detected a bright rim around the edge of the planet that may be nightglow — light emitted by oxygen atoms high in the atmosphere that recombine into molecules in the nightside. The prominent dark feature in the center of the image is Aphrodite Terra, the largest highland region on the Venusian surface. Bright streaks in WISPR, such as the ones seen here, are typically caused by a combination of charged particles — called cosmic rays — sunlight reflected by grains of space dust, and particles of material expelled from the spacecraft's structures after impact with those dust grains. The number of streaks varies along the orbit or when the spacecraft is traveling at different speeds, and scientists are still in discussion about the specific origins of the streaks here. The dark spot appearing on the lower portion of Venus is an artifact from the WISPR instrument.

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Venus is often called Earth’s twin due to a similarity in size and structure between the two planets. Images like the ones captured by Parker can help scientists determine why one planet has temperatures hot enough to melt lead, and the other became a haven for life.

“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,” Wood said. “Now, we finally are seeing the surface in visible wavelengths for the first time from space.”

Previous missions to Venus have shared insights about the planet using radar and infrared-detecting instruments that could penetrate the thick clouds, like NASA’s Magellan mission in the early 1990s.

The Magellan mission created this radar map of Venus in the 1990s.

The new images can help scientists learn more about the geology and minerals present on Venus because they glow in unique wavelengths of light when heated.

Parker will continue to use gravity assists from Venus as it spirals closer to the sun, but the trajectory of the next flyby won’t allow for imaging. The next opportunity to image Venus will be during the seventh and final flyby in November 2024.

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The spacecraft’s success with observing Venus while also revealing new insights about our sun has inspired the teams supporting other missions to gather images and data as they fly by Venus, like the BepiColombo mission to study Mercury and Solar Orbiter spacecraft.

Venus is the target of several upcoming missions later this decade like VERITAS and DAVINCI that will image and sample the Venusian atmosphere and create a new higher-resolution map of the surface in infrared light.

“By studying the surface and atmosphere of Venus, we hope the upcoming missions will help scientists understand the evolution of Venus and what was responsible for making Venus inhospitable today,” said Lori Glaze, director of the Planetary Science Division at NASA Headquarters, in a statement.

“While both DAVINCI and VERITAS will use primarily near-infrared imaging, Parker’s results have shown the value of imaging a wide range of wavelengths.”