NASA's Solar Probe Plus Mission

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NASA is sending a probe within 4 million miles of the sun in 2018.

NASA To Send Solar Probe To The Sun In 2018

Scientists hope that the mission will reveal why the solar surface known as the photosphere is not as hot as the sun's atmosphere known as corona. The surface of the sun is about 10,000 degrees Fahrenheit, but the atmosphere above it is far hotter at 3.5 million Fahrenheit.