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Solar Orbiter Is Now Halfway Between the Sun and Earth

The mission’s closest approach to our star will occur on March 26.

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Video of the Sun taken by Solar Orbiter during its last close passage in early 2022.
Gif: Solar Orbiter/EUI Team/ESA & NASA

The Solar Orbiter spacecraft, a joint mission of the European Space Agency and NASA, is officially halfway between our planet and the Sun. According to an ESA release, the spacecraft is currently 46.6 million miles from our host star.

Solar Orbiter began its scientific observations in November 2021 and will continue them on its way closer and closer to the Sun. The spacecraft is taking measurements of the solar winds and volatile corona.


Being situated so neatly between Earth and the Sun, the probe is giving researchers a unique opportunity to study space weather. Space weather is a feature of the solar wind, a steady stream of charged particles from the Sun that generates aurorae and occasionally disrupts electronics on Earth.

Solar Orbiter is taking a circuitous route to the Sun, but it’s (counterintuitively) saving energy by doing so. The orbiter is capitalizing on the gravitational pulls of Earth and Venus to slingshot itself inward. Besides providing great photo opportunities, these gravity assist maneuvers reduce the amount of fuel necessary to propel spacecraft, saving precious payload space.


Nearly 50 million miles on the space odometer doesn’t sound like much, until you remember that the Webb telescope only had to trek 1 million miles to its observation point in deep space.

The cubic Solar Orbiter (bottom left) peers at the Sun (top right) in this artist's impression.
An artist’s impression of Solar Orbiter at its closest approach of the Sun.
Illustration: ESA/ATG medialab

The orbiter’s current proximity to Earth and the Sun lets it gather useful data on how the solar wind blows through our solar system. Combining Solar Orbiter observations with data from spacecraft like IRIS (in Earth orbit) and the ESA’s SOHO (nearly a million miles from Earth) will give a more complete picture of the wind; like buoys in a sea of solar particles, the dispersed spacecraft will provide a dynamic look at space weather.

Daniel Müller, a Solar Orbiter project scientist with the ESA, said in a release that, “From this point onwards, we are ‘entering the unknown’ as far as Solar Orbiter’s observations of the Sun are concerned.”


The orbiter will make its closest approach—26 million miles from the Sun—on March 26. From March 14 to April 6, it will be within the orbit of Mercury, the closest planet to the Sun. While there (as before) the orbiter will collect data on the Sun’s surface and what it spews into space, but ESA researchers are hopeful that the spacecraft’s proximity to the Sun will offer some unique data on the solar campfires it discovered in 2020. Last year, scientists proposed that the campfires may be the convergence of magnetic fields on the Sun’s surface, but the situation remains unresolved.

“What I’m most looking forward to is finding out whether all these dynamical features we see in the Extreme Ultraviolet Imager (coined campfires) can make their way into the solar wind or not. There are so many of them!” said Louise Harra, a physicist at the Physical Meteorological Observatory in Davos, Switzerland and co-principal investigator for the Extreme Ultraviolet Imager.


Shortly after the spacecraft arrives at its closest approach later this month, we should receive some of the closest-ever images taken of the Sun.

More: Scientists May Know What’s Causing ‘Campfires’ on the Sun