How close can we get to the sun?

The closest point we can get to the Sun is at the surface of the solar system's inner planets, with Mercury being the nearest at about 36 million miles (58 million kilometers) away. Spacecraft can get much closer; for instance, NASA's Parker Solar Probe is designed to approach within about 4 million miles (6.4 million kilometers) of the Sun's surface. However, extreme temperatures and radiation levels present significant challenges for any mission approaching the Sun.