The Sun

Core: Internal Balance (Hydrostatic Equilibrium) Structure of the Sun depends on a balance between its internal forces – hydrostatic equilibrium -> a force that prevents the Sun from collapsing and a force that holds it together The inward (holding) force is the Sun’s own gravity, while the outward (non-collapsing) force arises from the Sun’s internal gas pressure

Near the Sun’s center, energy moves outward Region surrounding the core is the radiation zone

Above the radiation zone energy is more efficiently transported by the rising and sinking of gas –this is the convection zone

Convection manifests itself in the photosphere as granulation, numerous bright regions surrounded by narrow dark zones

Eclipses Solar Eclipse – Moon passes directly in front of the Sun - Day turns to night Total Eclipse – Perfect alignment of Sun, Moon, Earth - Planets, some stars become visible during the day - Can only be seen from small portion of daytime side of the Earth Corona becomes visible – ONLY visible during eclipse

Umbra – Central region of shadow - Total eclipse - Very small area Penumbra – Shadow outside of umbra - Partial eclipse - Large area

Lunar Eclipse When sun casts a shadow of the Earth onto the surface of the Moon.