Astronomy Topic: Solar System

ASTRONOMY TOPIC: SOLAR SYSTEM

 Definition: All space and objects within the Sun’s gravitational influence. (sun is sol, helios)

Topic 1: Our Star: the sun

1. The Sun is the largest object in our solar system and accounts for about 99% of the solar system’s mass.

2. The mass of the Sun influences the motions of planets and other objects in the solar system.

More Sun Stats; Mass: 333,000 times greater than

Earth; ~ 2.0 x 1030 kg Composition:

73% hydrogen25% Helium2% ‘other’ (oxygen, carbon, etc.)

Surface Temp: ~ 5800 K

Rotation:27 DaysWe rotate in 1 day!

Diameter:1,392,000 kmThat’s 109 times greater than Earth!

3. Sunspots

a. Sunspots appear as dark areas on the surface of the Sun.

b. The spots are about 3000o cooler than the rest of the surface of the Sun!

c. A sunspot can be as large as 100,000 km in diameter.

d. They follow an 11 year cycle and coincide with the Sun’s magnetic field reversals.

http://solarscience.msfc.nasa.gov/SunspotCycle.shtml

Sun’s layers, from inside out: Core

Site of fusion Radiative Zone

Converts energy from fusion reaction to radiation

Convective Zone Convection currents

carry energy to surface

Photosphere Emits most light

radiation

Chromosphere: Only visible during a solar eclipse

Corona: Outmost layer; also only visible during a solar eclipse.

Sunspots: Cooler areas on the Sun’s surface Solar Flare: A violent eruption of particles and

radiation. Prominence: An arc of gas ejected from the

chromosphere; may exceed temperatures of 50,000K

4. Stars like our star, the Sun, are typical main sequence stars.

It is not very large or hot.When it becomes old (uses up its hydrogen) it will expand and become a Red Giant.

http://sohowww.nascom.nasa.gov Age: 4.6 billion years old Red Giant stage in 5 billion years. It will nova and become a white

dwarf. 9

5. Stars: change hydrogen into helium during thermonuclear fusion in the core.

Topic 2. Measuring Distances and Energy in Space:

a. A.Lightyear is the distance light travels in a year.

b. Speed of light: 186, 000 miles/second

a. (670, 000, 000 miles/hr)c. Lightyear : 10 trillion km,

(or about 6 trillion miles )11

d. Electromagnetic Spectrum:

1. energy given off in transverse waves.

P. 14 ESRT

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2. All EME travels at the speed of light.

Longer wavelengths = lower energy have low frequency

Shorter wavelengths = more energy

have higher frequency

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3. Our star (sun) gives off primarily visible light has a continuous spectrum of VISIBLE LIGHT

Sun also gives off UV, infrared, and other wavelengths

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5. And around the sun…. 1.The 8 planets:

planets are large, non-luminous rotating bodies that orbit a star.

The Solar Wind

http://solarscience.msfc.nasa.gov/SolarWind.shtml

The solar wind streams off of the Sun in all directions at speeds of about 400 km/s (about 1 million miles per hour). The source of the solar wind is the Sun's hot corona. The temperature of the corona is so high that the Sun's gravity cannot hold on to it.

http://solarscience.msfc.nasa.gov/SolarWind.shtml

1.Our 4 inner planets are rocky, small and dense. a.Mercury and Mars have

almost no atmosphere.b.Venus is the ‘greenhouse’

planet.

a.Earth is the ‘blue’ planet with water in all 3 states of matter.

1.The asteroid belt has thousands of space rocks that orbit between Mars and Jupiter.

1.The 4 gas giants are found past asteroid belt. They are large, heavy, high in hydrogen and are low density. (jovian planets)

a. Saturn and Uranus have rings. b. All 4 have many moons c. All 4 have thick atmospheres d. Uranus rotates on its side

1.Kuiper Belt: contains many comets and the dwarf planets. a.Comets are made of dirt and

ice and ‘ignite’ when near the sun.

7. Oort Cloud: theoretical farthest part of our solar system. Almost a lightyear out.https://solarsystem.nasa.gov/multimedia/display.cfm?Category=Planets&IM_ID=10195