He is more focused on what the probe will learn on its seven-year mission as it loops repeatedly around Venus to propel it through the sun’s atmosphere. Among the key questions being explored: How is the sun, contrary to any phenomenon on Earth, so many magnitudes hotter in its corona, the surrounding area visible in an eclipse (1.7 million degrees Fahrenheit and up), than at its surface (about 10,000 degrees), and how does it expel matter at supersonic speeds?