As Tom Glazer taught us in 1961 (though I prefer the version by They Might Be Giants), the Sun is a mass of ionized gas, and the reason it looks so small is that it’s about 93 million miles away from the Earth. A human-staffed voyage to the Sun is impossible because that distance would ensure any human crew would run out of supplies before even getting close, and even if they did get close, they’d almost immediately burst into flames. This is why NASA has been trying for the next best thing: shooting a probe into the sun.
Originally launched in August of 2018, NASA’s Parker Solar Probe has spent that entire time slowly bumming around the Solar System, inching ever closer to the Sun proper. This week, the probe made history by crossing a threshold no other spacefaring device ever has. The Sun possesses a dense magnetic field that holds its superheated plasma in its vaguely spherical shape. The threshold of that field is known as the Alfvén point, and the moment something crosses that point, it can experience temperatures of up to 3 million degrees Fahrenheit.
☀️ Our #ParkerSolarProbe has touched the Sun!
For the first time in history, a spacecraft has flown through the Sun’s atmosphere, the corona. Here’s what it means: https://t.co/JOPdn7GTcv
— NASA (@NASA) December 14, 2021
To clarify, the Alfvén point is still about 5 million miles away from the Sun proper, but that just shows you how immeasurably intense its heat truly is, so to even get that close is an incredible scientific achievement, not to mention a testament to the construction of the Parker Probe. Despite entering that point of intense heat, the probe’s instruments were still able to successfully relay its status to NASA mission control.
The probe is still bumming around out there, ready to swing by the Sun again in a couple of years. Based on estimates, when the probe comes around again in 2023, it’ll get even closer than last time.