Our Expert Voices conversation about the 2017 solar eclipse.

One big question scientists still have about the Sun is why its corona, the outer atmosphere, is so hot — millions of degrees — while the surface below is only thousands! Eclipses provide unique opportunities to get higher quality and speed images than are normally available, either from space or from the ground. During the total eclipse, we're using telescopes mounted on the noses of NASA's WB-57 research jets to observe the solar corona. By observing waves in it and measuring their direction, size, and speed, we hope to better understand how energy is transported up into the corona. With two jets flying at 50,000 feet, we'll get 7-and-a-half minutes of totality compared to only 2-and-a-half on the ground.

What it means: Studying how the corona is formed and how it evolves will lead to better understanding "space weather" hazards like flares and coronal mass ejections that can impact Earth and damage satellites, interrupt GPS and radio, and knock out power grids.

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Amy Harder, author of Generate
5 hours ago - Energy & Environment

Climate change goes mainstream in presidential debate

Photo illustration: Aïda Amer/Axios. Photo: Olivier Douliery-Pool/Getty

The most notable part of Thursday’s presidential debate on climate change was the fact it was included as a topic and assumed as a fact.

The big picture: This is the first time in U.S. presidential history that climate change was a featured issue at a debate. It signals how the problem has become part of the fabric of our society. More extreme weather, like the wildfires ravaging Colorado, is pushing the topic to the front-burner.

Finally, a real debate

Photo: Morry Gash/AP

A more disciplined President Trump held back from the rowdy interruptions at tonight's debate in Nashville, while making some assertions so outlandish that Joe Biden chuckled and even closed his eyes. A Trump campaign adviser told Axios: "He finally listened." 

The result: A real debate.

Biden to Trump: "I have not taken a penny from any foreign source ever in my life"

Former VP Joe Biden pushed back Thursday against allegations from President Trump, saying he had never profited from foreign sources. "Nothing was unethical," Biden told debate moderator Kristen Welker about his son Hunter's work in Ukraine while he was vice president.

Why it matters: Earlier on Thursday, Hunter Biden's former business partner, Tony Bobulinski, released a statement saying Joe Biden's claims that he never discussed overseas business dealings with his son were "false."