Venus as You've Never Seen It Before: The Night Side in Infrared (2 photos)
In visible light, Venus appears as a pale yellow, almost white, sphere devoid of any detail. This is due to the planet's extremely dense atmosphere and a continuous layer of clouds containing droplets of sulfuric acid, obscuring both its surface and deep atmospheric structures. But switch to infrared light, and Venus appears as a completely different world. 
What's Hidden Beneath the Clouds
This little-known image shows the night side of Venus, captured by the Japan Aerospace Exploration Agency's (JAXA) Akatsuki probe. The probe's infrared cameras allowed scientists to peer beneath the upper cloud layer and reveal the structure of the lower atmospheric formations, located at altitudes of approximately 35-50 kilometers—where some of the most powerful atmospheric processes on the planet occur.
The dark areas in the image are denser, cooler cloud masses. Bright areas appear where heat from Venus's hot surface passes through the lower atmosphere, illuminating the clouds from below. As a reminder, the average surface temperature of Venus is 462 degrees Celsius, and its thermal radiation is partially visible in the infrared range.
Atmospheric Superrotation
Akatsuki observations helped study one of Venus's strangest phenomena—atmospheric superrotation. The planet itself rotates extremely slowly: one Venusian day lasts 243 Earth days. But the atmosphere behaves quite differently—it orbits the planet in just 4-5 days, moving at speeds of up to 300 kilometers per hour.
Why does the atmosphere rotate dozens of times faster than the planet itself? Scientists don't yet have a definitive answer, but there are two hypotheses. One is related to uneven heating: the dayside of Venus receives an abundance of solar energy, while the nightside rapidly loses heat. This creates powerful currents that transfer energy from the illuminated side to the dark side. Gradually, these currents swirl into a global circulation, accelerating the entire atmosphere. 
Color image of Venus in visible light, obtained on July 5, 2007, by NASA's MESSENGER spacecraft
Another hypothesis suggests that atmospheric waves—disturbances arising from the interaction of winds with surface topography and cloud structures—play a key role. These waves can transfer momentum to the upper layers of the atmosphere, accelerating their rotation. Akatsuki's observations did indeed reveal complex wave structures in Venus's atmosphere, which may be involved in maintaining superrotation.
Akatsuki Mission
The Japanese probe Akatsuki was launched on May 20, 2010. However, on its first attempt, in December 2010, the spacecraft failed to enter orbit around Venus. Its second attempt with the planet was successful: on December 7, 2015, Akatsuki entered orbit and, in the following years, studied Venus's atmosphere in the ultraviolet, visible, and infrared wavelengths, as well as attempted to detect possible signs of modern volcanic activity.
At the end of April 2024, contact with the spacecraft was lost. On September 18, 2025, after unsuccessful attempts to restore contact, JAXA announced the end of the mission.
Data collected by Akatsuki continues to help scientists uncover the mysteries of one of the most extreme worlds in the Solar System and is also being used in planning future Venus missions, including the privately funded Rocket Lab Venus Life Finder mission, scheduled to launch in the summer of 2026. Its goal is to study the atmosphere and search for possible biomarkers—measurable substances (gases, molecules) that indicate the possible presence of life, including phosphine, which was reported in 2020.
