For the past few years, astrophotography enthusiasts like Mattias Malmer have been digging through the archives of old NASA missions, looking for data and color photos that they can combine and adjust into true-color images.
Collage of NASA photos of different planets, including some false-color, color-enhanced, and artificial color radar topography. Although short-lived, it had enough time to take and send to Earth color photographs of Venus. Either they will depict the infrared and ultraviolet in bright colors (bottom right), or they will convert the image to show colors visible to human eyes (bottom left).
What is the true color of Venus?
Venus is completely covered by a thick atmosphere of carbon dioxide and sulfuric acid clouds that give it a slightly yellowish appearance.
In the case of the radar images, which are essentially elevation maps, the color is simulated, based on photos of the surface taken by the Soviet landers. To overcome this problem, the researchers adjust the photos from the Mars missions using a color calibration patch attached to the spacecraft.
Is Venus red or yellow?
For more information about Venus, see Hubblesite’s press releases about Venus, and here’s a link to NASA’s Solar System Exploration Guide to Venus. With the hottest surface in the solar system, aside from the Sun itself, Venus is hotter than even the innermost planet, carbonized Mercury. This is one of the main reasons you’ll see Venus in different colors, as astronomers and scientists often edit the images to make landforms like canyons and volcanoes easier to see. To survive the short-lived Venera probes, their stay on Venus would presumably include unimaginably heavy insulation, as temperatures approach 900 degrees Fahrenheit (482 Celsius).
But most of the time the two planets are farther apart; Mercury, the innermost planet, actually spends more time in close proximity to Earth than Venus. Astrobiologists point out that the ring-like bonds of sulfur atoms, known to exist in Venus’ atmosphere, could provide microbes with a kind of coating that would protect them from sulfuric acid. The temperature, atmospheric pressure, and chemistry are much more pleasant higher up in those thick yellow clouds.
Why is Venus blue?
It would have been the same on Venus if it had had these habitable conditions for these billions of years. The atmosphere is mostly carbon dioxide – the same gas that causes the greenhouse effect on Venus and Earth – with clouds composed of sulphuric acid. Forty years ago, NASA’s Pioneer Venus mission found evidence that the planet may have had an ocean of water up to 300 metres deep. Its exact composition remains uncertain; some scientists suggest that there may even be life, although much would have to be ruled out before such a conclusion could be accepted.
Quite a few missions have been flown to Venus to try to discover and see what lies beneath these clouds of toxic carbon dioxide. The ultraviolet wavelengths gave them a chance to really see the cloud cover and its movement across the planet. But the questions they raise, along with Venus’ vanishing ocean, violently volcanic surface and hellish history, make a compelling case for returning to our temperamental sister planet.