The reason for the seasons, tides, eclipses

The Sun and The Moon

Sonduk (ruled from 634 - 647 AD)

Queen Sonduk ruled Sillia, one of the Three Kingdoms of Korea from 634 - 647 AD. During her reign, she had Cheomseongdae (Tower of Moon and Stars) built. It is believed to have been the first celestial observation tower in the Far East.

Our Sun

● It is a star at the heart of our solar system.● Of the 100 billion stars in the Milky Way

Galaxy, its size is average.● Contains 99.8% of the mass of our solar

system.● Composed of 74% hydrogen and 24%

helium. (Remaining is other elements in very small amounts)

● Approximately 4.5 billion years old.

The Sun is a miasma of incandescent plasma…..

● Plasma is the fourth fundamental state of matter. It does not act like a solid, liquid, or gas.

● Think of plasma as an electrically neutral medium of positively and negatively charged particles.

The Sun has six layers

1) core2) radiative zone

3) convective zone4) photosphere

5) chromosphere

6) coronasolar prominencesolar flare

1) Core

● 1.5 x 107 °C and high pressure● nuclear fusion occurs (hydrogen atoms fuse

together to produce helium and lots of energy)

2) Radiative Zone

● very dense plasma● temperature ranges from 2 x 106 °C to about

7 x 106 °C● light from the core takes about 100 000

years to pass through this zone because it is continuously absorbed the re-emitted

3) Convective Zone

● temperature ranges from 6 x 103 °C to about 2 x 106 °C

● hot plasma rises to the surface and cooler plasma will sink and be reheated

● this process of circulating plasma is called convection

4) Photosphere

● temperature is approximately 5 500 °C● considered the surface of the Sun● cooler spots are called sunspots

(temperature around 4 000°C) and are caused by disturbances in the Sun’s magnetic field.

5) Chromosphere

● temperature ranges from 6 000 °C to about 50 000 °C

● huge flares send electrically charged particles into the solar system

6) Corona

● average temperature of 1 x 106 °C● extremely hot and thin layer that is only

visible during a total solar eclipse● extends millions of kilometres into space

Flares and Prominences

Solar flares - gases and charged particles released above active sunspots

Solar prominences - slow, low energy eruptions of gas from the corona.

Eclipses

● an astronomical event where one celestial object is darkened or blocked from view of the Earth by another celestial object

● we can view solar or lunar eclipses from Earth

Solar Eclipse

● Sun’s diameter is 400 times the diameter of the moon and also 400 times farther away from Earth.

Lunar Eclipse

● occurs when the Earth is between the Sun and the Moon.

Homework

page 331 # 1- 5 , 7

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