Parker Solar Probe
What is Parker Solar Probe?
Probes & telescopes· Launched 2018-08-12 – 8th year ongoing (closest pass 6.1M km). The NASA probe that first flew into the Sun's outer atmosphere. At closest approach it passes 6.1 million km above the surface at 692,000 km/h, the fastest speed of any human-made object.
Mission timeline
Spacecraft specs
| Launch | 2018-08-12 |
|---|---|
| Closest | 6.1M km above the surface |
| Top speed | 692,000 km/h — fastest ever |
Figures are representative approximations. Source: compiled from NASA and IAU public data.
What it means that Parker touched the Sun
On 28 April 2021 Parker crossed a boundary called the Alfvén surface for the first time, at 18.8 times the Sun's radius. Outside this boundary the solar wind breaks free and flows away. Inside it, the gas is still held by the Sun's magnetic field and moves with the Sun. The region inside is therefore counted as part of the Sun's atmosphere, which is why the crossing was described as touching the Sun.
During each closest approach Parker does not talk to Earth. Its shield must point exactly at the Sun, so the probe steers itself, runs its instruments and stores its data on its own. After the pass on 24 December 2024 the team waited several days, and late on 26 December (US Eastern time) it received a beacon signal meaning all was well.
The probe is named for physicist Eugene Parker, who predicted the solar wind in 1958. It was the first time NASA had named a spacecraft after a living person. Parker watched the launch in 2018 and died in 2022.
The mission in depth
Parker Solar Probe was launched on 12 August 2018 on a Delta IV Heavy rocket. Getting close to the Sun is harder than it sounds. Earth moves quickly around the Sun, and a spacecraft leaving Earth keeps that speed. To fall inward, Parker had to shed speed, which it did by flying past Venus seven times and tightening its orbit step by step.
On 24 December 2024 Parker came within 6.1 million km of the Sun's surface, about one twenty-fifth of the Earth–Sun distance. It was moving at 692,000 km/h, fast enough to cross the width of the United States in about 25 seconds. Its orbit now takes 88 days, so it returns to the same distance again and again.
The probe is protected by a carbon-composite shield about 11 cm thick. Its front face heats to nearly 1,400 °C, while the body in its shadow stays close to room temperature. The Sun's outer atmosphere, the corona, is over a million degrees, but its gas is so thin that the heat actually delivered can be blocked by the shield.
Parker is trying to answer two questions: why the corona is hundreds of times hotter than the surface below, and where the solar wind gets its speed. Its biggest surprise so far has been switchbacks, sudden zigzag kinks in the magnetic field of the solar wind, which scientists are studying for clues to how the wind is born.
Frequently asked
- When did Parker Solar Probe launch?
- Parker Solar Probe was launched on 2018-08-12.
- How close does Parker Solar Probe get to the Sun?
- The closest of Parker Solar Probe is 6.1M km above the surface.
- How fast is Parker Solar Probe travelling?
- The top speed of Parker Solar Probe is 692,000 km/h — fastest ever.
Related
Figures are representative approximations. Simulated positions use J2000 mean elements.