Venus is one of the most extreme and enigmatic planets in our solar system. Surface temperatures can soar to 480°C (896°F), with sulfuric acid rain falling from its thick atmosphere. The planet’s crushing atmospheric pressure is equivalent to what one would experience deep in Earth’s oceans. However, Venus stands out for an entirely different reason—its unique rotation cycle.
A day on Venus lasts longer than a year. While it takes 225 Earth days to complete an orbit around the Sun, the planet takes 243 days to rotate once on its axis. Adding to its peculiarity, Venus is the only planet in the solar system that rotates in the opposite direction compared to most other planets.
The Consequences of Venus’ Anomalous Rotation
This unusual rotation has profound effects. Due to its slow spin, one side of the planet endures prolonged exposure to intense solar radiation, while the other remains in darkness for extended periods. Data from the Venus Express spacecraft, launched by the European Space Agency (ESA), revealed significant differences between the planet’s day and night sides. For the first time, scientists observed unique cloud formations and unexpected atmospheric shifts, visible only in Venus’ perpetual night.
Was Venus Once Habitable?
Research suggests that Venus may have once been similar to Earth. A 2019 study by NASA’s Goddard Institute for Space Studies proposed that Venus might have harbored shallow oceans for two to three billion years. The planet could have maintained temperatures between 68°F and 122°F (20°C–50°C), making it potentially habitable. However, about 700 million years ago, a catastrophic resurfacing event released massive amounts of carbon dioxide, triggering a runaway greenhouse effect. This transformed Venus into an inhospitable inferno, with atmospheric temperatures reaching 1000°F (537°C).
The Mystery of Venus’ Ashen Light
One of Venus’ longest-standing mysteries is the Ashen Light—a faint glow observed on the planet’s dark side during its crescent phase. This phenomenon, first documented in 1643 by Italian astronomer Giovanni Battista Riccioli, has been reported by numerous astronomers over the centuries. However, some renowned scientists, including William Herschel, never observed it, leading some experts to dismiss it as an optical illusion or an instrumental error.
Despite ongoing skepticism, the mystery persists. A telescope in Hawaii once detected a faint green glow in Venus’ atmosphere, which scientists suggest could be caused by ultraviolet light breaking down carbon dioxide molecules. Another hypothesis proposes that frequent lightning strikes illuminate the planet’s sky, while some believe the Ashen Light might be an equivalent of Earth’s auroras. However, given Venus’ weak magnetic field, this explanation remains unlikely.
A rather bizarre 19th-century theory by Bavarian astronomer Franz von Gruithuisen speculated that the Ashen Light was caused by fires set by intelligent beings on Venus—perhaps for agricultural purposes or celebratory events. While modern science has largely debunked this idea, the true cause of this phenomenon remains unknown.
China’s Upcoming Mission to Venus
Interest in Venus has surged in recent years, with several upcoming missions aiming to explore the planet further. China is planning a mission called Venus Volcano Imaging and Climate Explorer (VOICE), which is set to launch in 2026 and enter Venus’ orbit in 2027. This spacecraft will study geological activity, atmospheric composition, and potential past habitability.
The mission will use advanced polarimetric synthetic aperture radar to map Venus’ surface and a multi-spectral imager to observe the planet in various wavelengths, from ultraviolet to near-infrared. This mission is one of 13 candidate projects under the Chinese Academy of Sciences’ third Strategic Priority Program on space science. It is currently being evaluated for feasibility, budget, and technological readiness.
A Global Effort to Explore Venus
China’s interest in Venus aligns with a broader global push to explore the planet. NASA has announced two upcoming Venus missions:
- VERITAS (Venus Emissivity, Radio Science, InSAR, Topography, and Spectroscopy)
- DAVINCI+ (Deep Atmosphere Venus Investigation of Noble gases, Chemistry, and Imaging)
Additionally, the European Space Agency (ESA) is developing the EnVision spacecraft, and India is planning to launch the Shukrayaan-1 orbiter in the coming years. Even private space companies, such as Rocket Lab, have expressed interest in sending probes to Venus.
Russia, historically a leader in Venus exploration, had planned a Venera-D mission for 2029. However, due to geopolitical tensions following the Russia-Ukraine conflict, potential NASA involvement in the mission has been canceled.
The Future of Venus Exploration
With multiple countries and agencies rekindling their interest in Venus, we are on the verge of a new era of planetary exploration. Scientists hope that future missions will finally provide answers to lingering questions, such as the planet’s past habitability, volcanic activity, and atmospheric mysteries. As technology advances, the secrets of Earth’s “evil twin” may soon be uncovered.
