On August 12 at 3:31 a.m., NASA’s Parker Solar Probe left Earth on a mission to touch the sun. The probe is named for Caltech Distinguished Alumnus Eugene Parker (PhD ’51), whose research revolutionized our understanding of the sun and interplanetary space. In the 1950s, Parker predicted the existence of supersonic solar wind, a flow of charged particles that stream off the sun, accelerating at supersonic speeds. “I’m proud of the fact that I thought of the solar wind,” Parker said. “It was an exercise in pursuing curiosity, which is the main motivation for studying physics, from a personal standpoint.”

The Parker Solar Probe will travel through the sun’s atmosphere, closer to the surface than any spacecraft before it, providing humanity with the closest-ever observations of a star. It will touch the sun to study the source of solar wind, the sun’s blistering corona—which, at several million degrees Celsius, is hotter than the surface of the sun itself. At the closest approach to the sun, the Parker Solar Probe will be the fastest spacecraft of all time, hurtling around the sun at speeds over 430,000 mph.

This is the first time NASA named a mission after a living person, and Parker was in Florida to watch the launch of his namesake spacecraft. Aboard the spacecraft is a memory card containing photos of Parker and his groundbreaking 1958 paper on solar wind. The card is inscribed with the following message from Parker: “Let’s see what lies ahead.”