The Sun

The sun is the only non-terrestrial object we see regularly in the daytime

sky with the exception ofthe moon.

Every aspect of human Existence “revolves”

around the sun.

Some facts about out Star

• The sun is an average/smallish size star.

• It is still large enough in volume to swallow the Earth more than 1 million times over.

• 99.9% of all the matter in our solar system is contained within the sun.

• The sun is a “G2” type star, yellow star.

• It is 4.5 billion years old (1/2 way through its life span).

• It fuses hydrogen in its core, so it’s a main sequence star.

Distinguishing features from other stars

1. It’s a single star so it doesn’t share its system

with another star. (So stars are in binary or two star systems.)

2. It is the only star we know of which harbors life within its system.

Chemical Composition

73% Hydrogen

25% Helium (a product of H Hydrogen fusion in core)

2% Carbon, Nitrogen, Oxygen Iron & a tiny bit of other elements

Origin of name

•Roman God:• Sol

•Greek God: • Helios

•Egytian God: • Ra

Diameter

1,390,000 km

Rotation

At equator: 25 days

At poles: 35 days

Not a uniform rate because it is a huge ball of gas

Temperature

• Photosphere: 5500 ˚C

• Core: 15.6 million ˚C

Density

1.41 g/cm3

Would it float in water?

The Sun is like Ogres or onions it has … Layers

Corona• Outermost atmosphere of the sun

• Extends for millions of kilometers into space

• Very hot 1.8 million ºF or 1 million ºC

• Field of electrified gas, the shape is determined by magnetic fields on the surface of the sun.

• Coronal mass ejection is when billions of tons of coronal electrons, protons, and gases are launched into space.

•It releases incredible amounts of radiation (UV and X-rays) and other slower particles

•As a result of this we see the auroras, Northern or Southern Lights.

•These cause magnetic storms on Earth which occasionally interfere with our radio and power grids.

Corona Continued

Chromosphere• Found beneath the corona

•Much cooler than the corona•17,000 ˚F or 9725 ˚C

•Red or Pinkish in color

•Visible during a total solar eclipse

•1200 km thick

Photosphere

• Surface of the sun-gives off light

• Not smooth or featureless it is spotted by gas enormous bubbles.

• Sunspots located here

• 330 km thick

Convection Zone

•Convection is the circulating of heat due to different temperature and densities.

•On the sun this is the area where the energy from the core is filtered and circulates.

•It is the upper 15% of the sun’s interior, and is about 10,000 km thick.

•Hot gases closer to the core rise up and cooler gases at the surface plunge toward the interior.

Radiant Zone

•Radiant means to give off or transfer

•The radiant zone transfers energy from core to convection zone

•600,000 km thick

Core•Innermost layer or center of the sun 174,000 km thick

•The radiant zone and core take up 85% of the sun

•High pressure and temperature 27 million ˚F

•Energy is produced by nuclear fusion is released when the hydrogen nuclei fuse together.

•Each second 600 million tons of hydrogen slams together in the core to form He. Tons of matter is converted into energy E=MC2

•the interior of the sun

Our Sun’s Features

Solar Winds

•Boiling off of outer atmosphere

•Consists of fast moving, charged particles (protons and electrons)

•Causes auroras (Northern and Southern Lights)

Solar Wind Video

• http://science.discovery.com/videos/the-planets-the-sun-solar-wind.html

Solar Flares

•Sudden eruptions of energy on solardisk, lasting minutes to hours, emittingcharged particles

•March 1989a solar flare caused 6 million

people in Quebec to lose power

Prominences

•Strands of relatively HOT glowing gas in thesolar corona, often looping hundreds of km and raining back on the surface.

•Prominences are brighter than other areas of the corona.

Filaments

•Strands of cool gas suspended over Photosphere by magnetic fields.

•They appear dark against photosphere.

Sunspots

• They form at the base of magnetic fields

• They are dark spots on the sun’s surface because they are emitting less visible light than the surroundings.

• They can be the size of Earth or larger

• Lifespan -> a few hours if small, several months if large

•They occur in 11-year cycles and effect weather on Earth(fewer sunspots = cooler weather)

Faculae

•Bright spots in photosphere that appear between the solar granules.•Enormous bubbles of hot gas.

Prominences vs. Filaments • Found in the

photosphere

•Darker other areas of the sun.

• Found in the corona

•Brighter and hotter than other areas of the corona

•Bigger and travel higher

Solar Eclipses

Eclipse from Space of Earth

•Chinese astrologers wrote of an eclipse occurring over 4000 years ago.

•Historians and astronomers believe that this was an eclipse that happened on 22 October 2134 B.C.

•Two astrologers at the time, Hsi and Ho, had apparently failed to predict this eclipse, and so were beheaded.

Solar Eclipses

•Earth’s moon lines up in the sky with the sun blocking the light of the sun.

•The size of the moon in the sky is almost the exact size of the sun.

Total Eclipse

•Moon passes in front and blocks the sun entirely (except for the cornona)

•Next one in the US will be in 2017 on August 21st

•It will travel in a path from Oregon to South Carolina.

Annular Eclipse or Partial Solar Eclipse

•Moon passes in front of the sun but doesn’t entirely block the sun, leaving a “ring”of the sun so it does not get dark out.

•This happens because the moon’s orbit is not perfectly circular.

Fun Eclipse Facts• The moon’s shadow moves at 1700 km/hour (1,048

mi/hr) .• Maximum totality is ~7 ½ minutes.• Every place on Earth will see a total solar eclipse about

every 400 years.• Partial Solar Eclipses occur more frequently than lunar

eclipses ( by 5:3).• There must be at least two partial solar eclipses every

year.• There can be two solar eclipses in back to back months

with a total lunar eclipse in between.• This triple eclipse can occur twice during an eclipse year

(1935, 2160).• Seven eclipses is the maximum - 4 solar, 3 lunar (1982,

2485).

How can we predict eclipses?

•The orbits of the planets and moon are consistent so eclipses follow a predictable pattern that can be calculated.