
(News from NASA)
As it sped away from Venus, NASA’s Mariner 10 spacecraft captured this seemingly peaceful view of a planet the size of Earth, wrapped in a dense, global cloud layer. But, contrary to its serene appearance, the clouded globe of Venus is a world of intense heat, crushing atmospheric pressure and clouds of corrosive acid.
This newly processed image revisits the original data with modern image processing software. A contrast-enhanced version of this view, also provided here [and seen above] makes features in the planet’s thick cloud cover visible in greater detail.

This view is a false color composite created by combining images taken using orange and ultraviolet spectral filters on the spacecraft’s imaging camera. These were used for the red and blue channels of the color image, respectively, with the green channel synthesized by combining the other two images.
Flying past Venus en route to the first-ever flyby of Mercury, Mariner 10 became the first spacecraft to use a gravity assist to change its flight path in order to reach another planet. The images used to create this view were acquired by Mariner 10 on Feb. 7 and 8, 1974, a couple of days after the spacecraft’s closest approach to Venus on Feb. 5.

[Editor’s note: for comparison, the originally-published version of Mariner 10’s view of Venus looked like this—visible light (L) and ultraviolet light (R):]
Source / see the remastered image on NASA’s online Photojournal here.