Solar wind
Topic: Origin and Evolution of the Earth and the Solar System · NCERT: Class 11, Ch 2 "The Origin and Evolution of the Earth"
Meaning
The solar wind is a steady stream of charged particles flowing out from the Sun in all directions. It never stops, but it gets stronger when the Sun is more active. In the early solar system, the solar wind stripped away the first hydrogen-helium atmosphere of the Earth and the other terrestrial planets (the inner, rocky planets). This was the first stage in the evolution of the Earth's atmosphere. Today the Earth's magnetic field shields us from most of it.
Example
India's first solar observatory, Aditya-L1, was launched on 2 September 2023. It sits in a halo orbit (a looping path) at Sun-Earth L1, about 1.5 million km sunward of Earth. From there it studies the solar wind before it reaches the Earth, which helps give early warnings.
Don't confuse with
- Coronal mass ejection (CME): a single huge cloud of charged gas thrown out by the Sun in one burst. The solar wind is a constant, steady flow.
- Degassing: the release of gases from the Earth's hot interior, which built the second atmosphere. The solar wind removed the first atmosphere. It did not create one.