Space Science Chapter 16

Universe Galaxy Universe & Galaxies 16.1 everything physical that exists in space. Galaxy Collection of stars bound together by gravity.

Measuring Distance in space 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 In a car this would take over 10 million years

What does that mean about the light you see from them? What you see is history 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? Alpha Centauri is the closest star other than the sun.

What is the name of our galaxy? Galaxies The nearest galaxy to our own is more than 2 million light years away from our galaxy. What is the name of our galaxy? Andromeda galaxy is the closets to ours. Our galaxy is the milky way Estimates are that there are 100 billon galaxies

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

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??? Our solar system is located about midway between the bule and the outer edge. See picture at the top of page 529

There are 3 types of galaxies Types are based on the shapes of the galaxies Spiral Elliptical Irregular

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. Page 529 book

Older than spiral galaxies Stars are older and no spiral arms. Elliptical Galaxies Older than spiral galaxies Stars are older and no spiral arms. Older stars are redder in color. Elliptical galaxies vary greatly in size.

Some contain very little gas or dust particles. Irregular Galaxies Some contain very little gas or dust particles. Some are clouds of matter that never gave rise to stars.

Origin of the Universe So, how did it all begin???

The Big Bang Theory Origin of the Universe 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.

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. Cosmic background radiation is a dim signal at microwave wavelengths

The Red Shift 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. Using the Doppler effect of waves moving from objects moving away being stretched out. This stretching of waves shifts them to the red. This then shows that all galaxies are mving away from Earth. All galaxies are moving away from each other. Or the Unisvers is constatnly expanding.

Red Shift & Blue Shift

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. Expand forever Slow but never stop growing Collapse back into itself

Stars & the Sun 16.2 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.

Brightness of Stars 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.

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

Stars are massive balls of hydrogen and helium. 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.

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.

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.

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.

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.

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. Upper left is betelgeuse a red supergiant

The Hertzprung-Russell Diagram

The Solar System 16.3 “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)

My Very Excellent Mother Just Served Us Noodles

Pluto is no longer a planet 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)

They are located inside the asteroid belt. The Inner Planets These planets are relatively small and have rocky surfaces. Why are they called the inner planets? They are located inside the asteroid belt.

The Outer Planets Larger than inner planets and composed of large gas clouds. They are called the gas giants. Jupiter What is the largest planet?

Covered with craters (caused by what?) Phases of the moon 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

Eclipse Solar eclipse When the moon blocks out the suns rays.

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

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

The Tides