Polar regions on Venus are colder than anywhere on Earth, study shows

Despite being only the second closest planet to the sun, Venus is far and away the hottest world in the solar system, with mean surface temperatures topping 850 degrees Fahrenheit (450 Celsius / 725 Kelvin) in most areas – but new data has revealed that this is not always the case.

In fact, as part of its swan song before it descended through the planet’s atmosphere, the ESA’s Venus Express probe revealed that the polar regions have a surface temperature of -250 degrees Fahrenheit (-250 Celsius / 116 Kelvin), making them far colder than any point here on Earth.

These previously unexplored polar regions are also covered with atmospheric waves, the agency explained in a statement earlier this week. A study detailing the final data from Venus Express, collected before the probe lost contact with Earth and officially came to a close in late 2014, was published in the April 11 edition of the journal Nature Physics, the ESA added.

Atmosphere less dense than expected, dominated by strong Earth-like waves

Venus Express, which was Europe’s first mission to Earth’s so-called sister planet, was launched in November 2005 and was designed to spend 500 days analyzing the world using a vast array of different scientific instruments. It ultimately ended up completing eight years worth of work, and during the final months of its mission, completed a series of low-altitude orbits.

These low-altitude orbits enabled Venus Express to experience measurable atmospheric drag and use its onboard accelerometers to measure how much deceleration it experienced while travelling through the planet’s upper atmosphere and revealing its density, lead author Ingo Müller-Wodarg from Imperial College London explained.

Amazingly, none of the instruments on board Venus Express were originally designed to collect in-situ data from the atmosphere, Müller-Wodarg said, but the team realized after the orbiter had actually launched that they would be able to conduct such observations. The measurements used in their study were collected in June and July 2014 at altitudes of 130-140 km above the planet’s polar regions, in a part of the atmosphere that had not been previously studied.

The collected data revealed that the polar temperature was up to 70 degrees colder that had been predicted, with average temperatures of just -157 degrees Celsius (-250 Fahrenheit / 114 Kelvin) in these regions. They also found that the polar atmosphere is less dense than previous expected (22 percent less at 130 km; 40 percent less at 140 km), and that the area was dominated by strong atmospheric waves similar to those that helped shape Earth’s atmosphere.

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Image credit: ESA

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