1. The Solar Atmosphere:
* Photosphere: This is the visible surface of the Sun, the layer we see with our eyes. It's about 400 km (250 miles) thick and has a temperature of about 5,500 °C (9,932 °F).
* Chromosphere: This layer lies above the photosphere, extending about 2,000 km (1,240 miles) outward. It's much fainter and hotter than the photosphere, reaching temperatures of 10,000 °C (18,000 °F).
* Corona: The outermost layer of the Sun's atmosphere, extending millions of kilometers into space. It's incredibly hot, reaching millions of degrees Celsius, and is characterized by its low density and faint light.
2. The Heliosphere:
* Solar Wind: A continuous stream of charged particles (mainly protons and electrons) that flows outward from the Sun, carrying the solar magnetic field with it.
* Heliosphere: This is the vast bubble of solar wind that envelops the Sun and extends far beyond the orbit of Pluto. It's shaped like a teardrop, with the Sun at the wider end. The heliosphere shields the inner Solar System from interstellar radiation.
How Far Does It Extend?
* Corona: The corona is the outermost part of the Sun's atmosphere and extends millions of kilometers into space.
* Heliosphere: The heliosphere, defined by the solar wind, extends far beyond Pluto, reaching the heliopause, where it encounters the interstellar medium. This distance is estimated to be around 120 astronomical units (AU), or about 18 billion km (11 billion miles).
Important Note: The Sun's layers and structures are not static. They change over time, influenced by solar activity, such as flares and coronal mass ejections.
Beyond the Heliosphere:
* The boundary between the heliosphere and interstellar space is called the heliopause.
* After the heliopause, we enter the interstellar medium, the vast space between stars filled with gas and dust.
