Venus is shrouded in a veil of mystery. The yellowish “lower haze” at the bottom of its atmosphere was discovered by the Venera and Pioneer Venus probes in the 1970s. These spacecraft were some of the first to successfully send images of the planet back to Earth, but the haze they saw went unexplained for decades. Now the mystery Venus was keeping has been unveiled.

What nobody knew then was that the haze is an accumulation of particles from meteorites. “Shooting stars” that burn up in the atmosphere leave behind cosmic dust particles, and after sulfuric acid interacts with these particles, it leaves behind a haze. Planetary scientist Hiroki Karyu and his research team at Tohoku University in Sendai City, Japan, finally figured out how the haze formed using a microphysical model. This type of model involves microphysics—the micro-scale processes that create clouds and precipitation on Earth and other bodies.

“The continuous influx of cosmic dust is sufficient to sustain this lower haze layer with the particle size distribution observed by the entry probes,” Karyu said in a study published in Nature Astronomy. “These haze particles of cosmic origin act as efficient condensation nuclei, promoting cloud formation in the main cloud deck even far from their initial source.”

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A four-person crew rocketed into orbit Thursday from Cape Canaveral Space Force Station, Florida, heading for a six-month expedition on the International Space Station.

Riding a Falcon 9 rocket and Dragon spacecraft, the four crew members departed from Space Launch Complex-40 at Cape Canaveral at 11:10 am EDT (15:10 UTC) Thursday. Nine minutes later, they were in orbit to begin closing in on the space station for docking Thursday evening.

The launch was delayed from mid-September to replace a balky valve in the Dragon spacecraft's propulsion system, a task that involved cutting into a propellant line inside the ship to swap out a faulty component.

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Deep Blue took down Garry Kasparov at chess in 1997, AlphaGo beat Lee Sedol at Go in 2016, and poker bots have been beating professionals for years. But one classic game called Stratego held out. Even DeepMind, with its exceptional budget, couldn't build a machine that reliably beat the best human players.

Now, a team of researchers from Carnegie Mellon, MIT, New York University, and Stanford University has done it. Their AI, called Ataraxos, beat Pim Niemeijer, arguably the best Stratego player of all time, 15 games to one, with four draws. And it took just 16 GPUs and a few thousand dollars to train it.

Hidden armies

In Stratego, each player gets 40 pieces representing military ranks, from a marshal down to a spy, plus bombs and a flag. You win by capturing the opponent's flag. Your opponent knows where your pieces are, but not what they are. Identities are revealed only when two pieces collide in battle—the weaker one is removed, and the identity of the winner is revealed. That makes Stratego an imperfect-information game, just like poker, which computers cracked years ago. “There's something super distinctive about Stratego, which is that it is a massive amount of hidden information that unfolds over a very long time scale,” said Eugene Vinitsky, a researcher at NYU and co-author of the study.

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