The sun and our solar system Grade 9 Science Space Part 2

Astronomy: The branch of science that studies objects beyond the Earth (in “outer space”) Celestial body: Any object in space The Universe: Everything that exists Key Terms

Star: A massive celestial body composed of hot gases that radiates large amounts of energy Luminous: glowing, light producing Planet: a celestial body which orbits a star Satellite: a celestial body which orbits another body Orbit: the closed path an satellite takes around another body Moon: a natural satellite of a planet Solar system: the Sun and all of the celestial bodies that orbit it

Our Star: The Sun Core Temperature: 15,000,000 °C

100 billion tonnes of Dynamite would have to be detonated every second in order to match the Sun’s energy output!! The sun is getting hotter…becoming 10% more luminous every billion years If the sun where to “turn off”, within a week the temperature of the earth would be zero degrees F DID YOU KNOW?!?

Age: 5 billion years Diameter: 1,391,000 km (109 X the size of Earth) Composition: 94% Hydrogen 6% Helium 0.13% other

High temperature + High pressure = Particles moving quickly and colliding at high speeds and fusing Releases enormous amounts of energy What human energy source does this remind you of? The Sun’s Energy Source: Nuclear Fusion

Core: -2% of Sun’s volume, 50% of Sun’s mass. DENSE!!! -nuclear fusion happens here…600 tonnes of H to He per second °C Radiative zone: -Energy moves away from the core -Photons can take up to 1 million years to reach the next layer -380,000 km thick -32% of sun’s volume, 48% of sun’s mass °C Layers of the Sun

Layers continued… Convective zone: -66% of Sun’s volume, 2% of Sun’s mass (LOW DENSITY) -Convective currents form “cells” -hot gas rises (away from core) -cool gas falls (toward core) -5500°C Photosphere: -Visible “surface” (NOT solid!) looks like boiling liquid -Light and other radiation begins to escape -6000°C -140,000 km thick

Chromosphere: °C -Thousands of kilometers thick -Composed of spicules Corona: -Visible during a full solar eclipse -1,100,000°C The Sun’s “Atmosphere”

Video TG7tCF0 Virtual Tour

Sunspots on the Photosphere Cooler regions on the photosphere ( ºC cooler) Do not emit as much light and appear darker. Can last a few days to a few months. Largest ever: 1.8*10 10 km 2 (36 x Earth’s surface area!!)

Solar Storms -Gas and charged particles emitted from the sun’s surface Coronal Mass Ejections Lower energy Ejection of gas last several days to several weeks Flare: Higher energy Gas and charged particles ejected last a few minutes to a few hours Occur near sunspots r/sdo_2010/sdo_02 eather/sob_multimedia/flvswm_15

Solar Activity Affects the Earth 1. Solar winds are guided by the Earth’s magnetic field (strongest near the poles) They interact with particles in the Earth’s atmosphere, creating the aurora borealis and aurora australis

2. Solar activity/storms can… interfere with satellites and cellphone/TV connections Cause increased radiation for astronauts 3. The sun provides all of our incoming energy! In the form of electromagnetic radiation

Electromagnetic (EM) radiation g

Blocks (reflects) bad radiation (UV) Role of our Atmosphere Lets in (absorbs) good radiation (infrared and visible) Insulates the Earth: keeps us warm, keeps temperatures from swinging drastically in the day and the night, the summer and winter.

EM radiation = heat CO2 traps heat!

Reading: Textbook questions: #2-3 on pg. 308, #2-5, and 8-9 on pg. 312 Homework

The solar system

Sources