NASA's Parker Solar Probe has made the closest-ever approach by a spacecraft to the sun. The probe passed within 15 million miles of our star Monday evening.
That might not seem super close until you consider that the sun's outer atmosphere — known as its corona — can reach temperatures in the millions of degrees Fahrenheit. NASA says the area the probe is currently passing through contains material at 3.6 million degrees Fahrenheit.
Luckily for the probe, there's too little of that material to convect or conduct the sun's heat, so the biggest problem it's facing is radiation. That alone is enough to warm its heat shield up to 820 degrees Fahrenheit.
The temperature of the corona, and the question of why it's hundreds of times hotter than the sun's surface below, are two of the things the probe is intended to investigate.
NASA expects the probe to make 24 more similar solar approaches over the span of its mission.
