Visible around the darkened Sun during a total solar eclipse, the corona is the luminous envelope surrounding the Sun outside the chromosphere—the upper, rarefied solar atmosphere. The basic structure of the corona is formed by coronal loops, which result from the twisted solar magnetic flux within the Sun and exhibit a wide range of temperatures. How are these massive coronal loops related to the coronal heating problem—the mystery of why the Sun's corona is far hotter than its surface?
George Bernard Shaw
Back in the day
The Holland Tunnel, which connects Manhattan to Jersey City, was designed specifically for automobile traffic and included ventilator systems to reduce carbon monoxide exposure. One of first examples of ventilated design, the tunnel was an engineering marvel of the time. Construction required workers to spend large amounts of time under high pressure. Upon exiting the tunnel, they underwent a depressurization process that prevented them from developing what painful physiological condition?
Born on a day like today
Tegnér was the most popular of the Swedish romantic poets. An optimistic nationalist in his youth, he wrote the militant anti-Russian Svea and Axel, followed by Frithjof's Saga, which is based on collections of Scandinavian sagas and is considered the masterpiece of the Swedish Gothic tradition. The son of a pastor and a bishop himself, his sermons and speeches are classics of the Swedish language. Subject to periods of madness, he composed what epic poem in an asylum?