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Our Sun is a giant plasma windbag spewing a constant stream of charged particles called the solar wind. This stream leaves the Sun at speeds around 400 to 800 kilometers per second and extends to the outer edge of the Solar System to about 125 astronomical units. Astronomers have long wondered about what feeds this powerful outflow.<\/p>\n
<\/p>\n Recently the ESA Solar Orbiter spacecraft observed tiny plasma jets a few hundred kilometers wide, occurring across the Sun. Each one flashes for a brief instant above the solar surface. Just as a tiny stream expands to create a raging river here on Earth, these minuscule jets combine to provide \u201cbackground\u201d power that blossoms into the fast and slow parts of the solar wind.<\/p>\n A research team led by Lakshmi Pradeep Chitta at the Max Planck Institute for Solar System Research, Germany used the probe\u2019s onboard \u2018cameras\u2019 to spot more tiny jets within coronal holes close to the Sun\u2019s equator. \u201cWe could only detect these tiny jets because of the unprecedented high-resolution, high-cadence images produced by EUI,\u201d said Chitta at the time of their discovery in 2023. They used the extreme ultraviolet channel of EUI\u2019s high-resolution imager, which observes million-degree solar plasma at a wavelength of 17.4 nanometers. At the time, scientists suspected these flares were at the heart of solar wind generation but didn\u2019t understand how widespread they were.<\/p>\n The team continued to use the Polarimetric and Helioseismic Imager (PHI), Solar Wind Plasma Analyser (SWA) and Magnetometer (MAG) to study the jets over the past year and a half. By combining these high-resolution images with direct measurements of the stream of particles and the Sun\u2019s magnetic field around the Solar Orbiter, the researchers spotted more tiny flares within coronal holes close to the solar equator. Based on those observations, they directly connected the solar wind measured at the spacecraft back to those same jets.<\/p>\n \nProbing the Solar Wind<\/h3>\n