Parker Solar Probe is designed to study the Sun and its hot outer atmosphere, known as the corona, from closer range than any other spacecraft to date. Launched August 12, 2018, its primary mission will consist of 24 orbits around the Sun, shaped by seven close encounters with Venus. At its closest, in 2025, it will pass less than four million miles (6.3 million km) from the Sun's surface. It will move faster than any other spacecraft in history, reaching a maximum of 430,000 miles per hour (690,000 kph) at its closest approach. Heavy shielding will protect the spacecraft from the Sun's intense heat and radiation. The craft is named for Eugene Parker, a solar physicist. He hypothesized the existence of the solar wind in the 1950s.