For the first time, a NASA spacecraft has photographed the surface of Venus in visible light—that is, as the human eye would see. The Parker mission has revealed never-before-seen images of our neighbor’s landform that may help explain how it became so inhospitable to life.
Until then, space photos of the planet’s surface were taken at ultraviolet or infrared frequencies. That’s because there is a dense layer of clouds around it, which prevents us from seeing directly what is underneath it.
In 2010 and 2011, Parker Solar Probe — on its journey to the Sun — made two flybys of Venus. She pointed the cameras of the modern instrument WISPR (Wide-Field Imager) to the dark side of the planet (which is opposite the Sun), and managed to obtain the never-before-seen images, in visible light spectrum lengths.
NASA combined the records into a video:
Not exactly the kind of photography we envisioned. Through the clouds, you can only see a glow emanating from the planet’s surface – brighter areas are lower; darker are higher – showing the relief of the planet, such as plains, plateaus and continental areas.
Only longer visible waves — bordering on the infrared, at the edge of the human eye — can make it through. They are, in fact, thermal emissions, which reveal temperature variations. Venus is so hot it glows; even its night side is around 460°C.
Image taken on July 11, 2020, by Parker Solar Probe’s WISPR instrument
Image: NASA/APL/NRL
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“It’s so hot that the rocky surface of Venus is visibly shiny, like a piece of iron pulled from a forge,” said Brian Wood, a physicist at the Naval Research Laboratory in Washington, D.C., and lead author of a study published this week. na revista Geophysical Research Letters.
On the bright side of the planet, it would not be possible to register these variations in brightness — as the thick clouds reflect 90% of the sunlight and obfuscate what comes from the surface. In the images, we also see a bright ring around the planet, called an “airglow”—a halo of oxygen in the atmosphere.
inhospitable twin
Venus, Earth and Mars, rocky planets, formed at the same time, but today they are very different. Venus was a twin planet of Earth—but it has become a hostile place for any life form, with extreme temperatures, crushing pressure, and corrosive acidity; while here it became an oasis.
The new images, combined with previous radar records, are helping scientists to understand this process of evolution and also to study the geology and composition of our neighbor — when heated, minerals glow at unique wavelengths. Past volcanic activity is suspected to have been responsible for such a thick atmosphere.
—Images from WISPR (left) and the Magellan spacecraft’s radar (right) show details of the planet’s relief and temperature
Image: NASA / APL /NRL; Magellan Team / JPL / USGS
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WISPR showed the Aphrodite Terra continental region, the Tellus Regio plateau, and the Aino Planitia plains. As the higher altitude areas are about 30°C cooler than the lower ones, they appear as dark patches amid the brighter plains.
“Venus is the third brightest object in our sky, but until recently we didn’t have much information about what the surface was like because our view of it is blocked by a thick atmosphere,” Wood said. “Now, we’re finally seeing the surface at wavelengths visible for the first time from space.”
The instrument, in fact, was developed to capture details of the solar winds that flow from the Sun. And the scientists wanted to take advantage of it to measure the speed of the clouds of Venus, since Parker would pass by the planet, on its way to our star. But WISPR was able to see beyond the clouds.
The only visible light images of Venus from the ground (black and white) date back to 1975, when the Soviet probe Venera 9 landed there — it was operational for 53 minutes on the surface, until it lost contact due to the extremely high temperatures.
By the end of this decade, new missions will try to unravel the mysteries of our neighbor, such as DAVINCI and VERITAS — both from NASA — and EnVision, from the European Space Agency (ESA).
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