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Space Science

Chapter 16

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•Universe –everything physical that exists in space.

•Galaxy–Collection of stars bound together by gravity.

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•Light Year (ly)–Distance that light travels in one year.

–Speed of light (c) 3.0 x 108 m/s

–9.5 x 1015m/yr

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•Did you know…the light you see from the sun actually left the sun 8 minutes earlier!?!•Nearest stars other than the sun are 4.3ly away (6.09 x 1016m)! What are they???•What does that mean about the light you see from them?

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The nearest galaxy to our own is more than 2 million light years away from our galaxy.

What is the name of our galaxy?

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Galaxies & Gravity

• Gravity draws clouds of dust together to form stars.

• Gravity draws stars, dust, and gas into larger units that we call galaxies.

• Gravity also causes galaxies to cluster together.

• Superclusters are large groups of galaxies drawn by gravity

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• Our solar system is inside of the Milky Way Galaxy.

• The galaxy contains clouds of gas and dust (interstellar matter).

• The galaxy has a bulge in the middle. Why???

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• There are 3 types of galaxies

• Types are based on the shapes of the galaxies

1) Spiral

2) Elliptical

3) Irregular

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Spiral Galaxies

•Often have spiral arms that contain material for forming new stars.

•Blue tint is due to the blue color of newly forming stars.

•Blue is most notable in the arms.

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• Older than spiral galaxies

• Stars are older and no spiral arms.

• Older stars are redder in color.

• Elliptical galaxies vary greatly in size.

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• Some contain very little gas or dust particles.

• Some are clouds of matter that never gave rise to stars.

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So, how did it all begin???

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The Big Bang Theory•If the universe is constantly expanding outward, then to go back in time would bring all matter to one point of origin.

•This would look like a giant explosion.

•According to this theory the explosion released all of the matter and energy that exists in the universe today.

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Is there support for the Big Bang Theory??

• In 1965 cosmic background radiation was discovered. It is thought that this is the remains of the energy of the big bang.

• The presence of these waves was predicted in the Big Bang Theory.

• The red shift also supports the theory.

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• Hubble’s Red Shift theory.

• Stars emit a pattern of spectral lines.

• Stars from other galaxies show the pattern shifted to the red end of the spectrum.

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Red Shift & Blue Shift

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Where is the Universe headed?•The universe is expanding, but at what rate? •Is it happening faster or is it slowing down?•The 3 possible results depend on how much matter there is in the universe.

1)Expand forever2)Slow but never stop growing3)Collapse back into itself

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• The Sun is an average star.

• The sun is much larger than

the Earth (about 110 times the size)

• The mass of the sun is 300,000 times the mass of Earth.

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•Depends upon the temperature, size, and distance from Earth.

•Stars don’t just produce energy in the form of light.

•They also produce High frequency x-rays and low frequency radio waves.

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Temperature and color of stars• Hotter objects glow with light of higher

intensity at shorter wavelength. This light is more toward the blue or violet end of the visible light spectrum.

• Cooler objects glow with light intensity at the longer wavelengths or more toward the red end of the spectrum.

Spectral Lines and composition

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Nuclear Fusion and Stars

•Stars are massive balls of hydrogen and helium.

•They are held together by the gravity caused by their own mass.

•Extremely high pressure and temperature result in nuclear fusion.

•This in turn releases energy outward.

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Life of a Star

• Stars have a life cycle just like other things in nature.

• A beginning, a middle, and eventually an end.

• The beginning is a nebula, or cloud of gas and dust that start to collapse inward due to gravity.

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• The cloud of gas begins to collapse due to its own gravity.

• As it collapses the cloud begins to spin.

• As the cloud gets smaller it spins faster.

• The center reaches high temperatures and pressures and the electrons are driven off of hydrogen.

• Nuclear fusion begins and a star is born.

• Fusion reactions produce an outward force.

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Balance of forces in a Star•The inward force of gravitational pull is balanced with the outward force of the energy of nuclear fusion in the center of the sun.

•Estimates are that this balance of forces on the Sun has existed for 5 billion years and should continue for another 5 billion years.

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Life cycle of the Sun• When fusion of hydrogen slows the

center of the sun will contract while the outer layers expand.

• The sun will then be a red giant.

• When the red giant begins to reach the end of its course it will become a white dwarf.

• When it cools completely it will become a brown dwarf.

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Stars larger than the sun

•These stars (1.4 times larger than the sun) become Supergiants.

•Due to the mass of these stars fusion stops, resulting in a massive explosion known as a supernova.

•After a supernova the star will become either a neutron star or a black hole depending upon its mass.

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• “Eight planets” orbit the sun(Copernicus)• The planets are:

• Planets move in elliptical orbits (Kepler)• They are visible due to the ability to reflect light.

Mercury, Venus, Earth, Mars,(Ceres) Jupiter, Saturn, Uranus, Neptune, (Pluto), (Charon, and 2003 UB 313)

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• My• Very • Excellent • Mother• Just• Served• Us• Noodles

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Pluto is no longer a planet! The giant asteroid Ceres, Pluto's moon Charon, and a large outer-solar system object called 2003 UB313 fall into the same category as Pluto (Dwarf Planets)

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• These planets are relatively small and have rocky surfaces.

• Why are they called the inner planets?

They are located inside the asteroid belt.

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• Larger than inner planets and composed of large gas clouds.

• They are called the gas giants.

What is the largest planet?

Jupiter

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• 385,000 km from Earth.• Covered with craters

(caused by what?)• Phases of the moon

–What are they?–What causes the

phases of the moon?The relative positions of Earth, Sun, and the Moon

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• Solar eclipse– When the moon blocks

out the suns rays.

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Lunar eclipse

When a full moon has the suns rays blocked by the Earth.

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Summer and Winter Solstice• In the Northern

Hemisphere winter solstice is the shortest day of the year.

• In the Northern Hemisphere summer solstice is the longest day of the year.

• What about the southern hemisphere?

June 21 or 22

December 21 or 22

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