Touching the Sun

The Parker Solar Probe is zipping through the sun’s outermost layers today at 213,000 miles per hour, enduring sizzling temperatures that would fry most other spacecraft. The probe will come within 15 million miles of the sun, reaching perihelion, its closest point, at 6:40pm EDT. But it’s so close even now that it hasn’t been able to send back data to Earth since March 30. The probe must keep its protective gear pointed straight toward the sun, leaving no wiggle room to point an antenna back toward Earth.The probe has flown this close once before, so it’s tying its own record on this approach. The previous record holder was the Helios 2 mission at 27 million miles, or nearly twice the distance. But by the end of its mission in 2025, the Parker Solar Probe will end up grazing the sun itself, only 3.83 million miles from its surface, within the sun’s outer corona layer.

Despite the sun being the closest star, and one that is under nearly constant observation, there are still many open questions about how the sun works. Scientists don’t understand how the solar wind accelerates particles the way it does, or why the sun’s corona is so much hotter than its surface despite being further away. By flying through the corona at temperatures nearing 2500 degrees F, researchers hope the Parker Solar Probe can offer answers to some of these questions.