Parker Solar Probe at closest approach
On Christmas Eve a human-made object passed closer to a star than ever before — 6.1 million km above the surface at 690,000 km/h, flying through the corona itself.
The moment of Parker Solar Probe at closest approach: https://nowsky.org/e/parker-perihelion — opens at the right place and time, replayable, no login.
Available views: Orbit ✓ · Sky — (not visible in the sky)
The story
On 24 December 2024 the Parker Solar Probe dipped to 6.1 million km above the Sun's surface — the closest any human-made object has come to a star — moving at 692,000 km/h, also a record for an artefact. The pass ran inside a tenth of Mercury's orbital radius, through the corona itself.
The approach was seven years in the making. After launch in August 2018 the probe skimmed Venus seven times, tightening its orbit each pass, and the final Venus flyby on 6 November 2024 set up the Christmas Eve perihelion. From here it repeats the same closest distance every 88 days on the same orbit.
An 11.4 cm carbon-composite heat shield took 1,400 °C while the body behind it stayed near room temperature. Contact with Earth is lost during perihelion; a simple "alive" beacon reached the Johns Hopkins Applied Physics Laboratory on the night of 26 December and confirmed success.
Flying inside the corona, Parker gathers clues to why that outer atmosphere is hundreds of times hotter than the surface. Evidence is accumulating that the magnetic "switchbacks" — zigzag folds that accelerate the solar wind — originate at the base of the corona. The orbit replay shows the spiralling seven-year trajectory and that final perihelion.
Why it matters
The coronal heating problem is more than sixty years old: a million-degree atmosphere above a 5,500 °C surface is as paradoxical as a room getting hotter the farther you stand from the stove. Parker is the first spacecraft to measure fields, plasma and particles inside that region, and at 6.1 million km it flies where the solar wind is still being born.
The practical stake is space weather. The solar wind and coronal mass ejections disturb satellites, power grids and communications; data taken at the source feed the models that forecast their arrival at Earth.
In engineering terms it is a victory for the heat shield and autonomous attitude control — a spacecraft that hides behind its shield for days without ground contact, proven over three closest passes in December 2024, March 2025 and June 2025.
How to watch
Parker is invisible to any telescope, let alone the eye; a perihelion is a data event rather than something to watch. NASA's mission pages give the perihelion time and the contact recovery, and the data come down over the following weeks.
The orbit replay begins at the 2018 launch, draws the orbit tightening through seven Venus flybys in time order, and slows at the perihelion of 24 December 2024. Tracked, the path seems almost to touch the solar disk — in reality it stays about nine solar radii above the surface.
The Sun itself must never be viewed unfiltered. Selecting the Sun in the sky view gives its current altitude and 24-hour track from your location, with the daytime sky following the real solar altitude.
See this for yourself — replay the moment in the orbit view
Background
The probe is named for Eugene Parker, who predicted the solar wind in 1958, was ridiculed for it, and was vindicated four years later by Mariner 2. It was the first NASA spacecraft named for a living person; Parker watched the 2018 launch and died in 2022.
The previous record for a close approach was Helios 2 in 1976 at 43.4 million km. Parker went inside a seventh of that distance, and in April 2021 it crossed the Alfvén surface to become the first spacecraft to fly within the corona.
ESA's Solar Orbiter, launched in 2020, images the poles from farther out and pairs with Parker. Their simultaneous observations are the first chance to measure the corona of a solar maximum (2024–2026) from inside and outside at once.
FAQ
How close and how fast?
6.1 million km above the surface at 692,000 km/h — both records for a human-made object.
Why did it not melt?
An 11.4 cm carbon-composite shield faces the Sun and the body sits in its shadow; the front reaches 1,400 °C while the instruments stay near room temperature.
Was this the last close pass?
No. It repeats the same closest distance every 88 days — including 22 March and 19 June 2025.
What is it trying to learn?
Why the corona is hundreds of times hotter than the surface, and where the solar wind is accelerated — inputs for space-weather forecasting at Earth.
Related
- Parker Solar Probe launch
- Mariner 2 — measuring the solar wind
- BepiColombo launch — to Mercury
- Parker Solar Probe — object index
- The Sun — object index
Times and figures are approximate — verify with official sources when planning travel. Simulation uses J2000 mean elements.