1. The Solar System-Test 1
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3. A. What is Astronomy? 1. Astronomy is the study of the universe.
This includes planets, stars, galaxies, black holes, moons, meteors, comets, asteroids and all of the matter that exists in space.
2. Astronomers are people who observe & study space.
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4. B. Modern Calendar
Our modern calendar is based on the observations of bodies in our solar system.
2. A year is the time it takes for the Earth to orbit the sun; year = revolution.
3. A month is the time it takes for the moon to orbit the Earth.
4. A day is the time it takes for the Earth to rotate once on its axis; day = rotation.
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5. The Size and Scale of our Universe
It is important to consider scale when we think about the universe.
Stars appear to be very small when viewed from Earth, but they are actually very large, some, like our sun, are bigger than Earth.
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6. The Scale of our Solar System
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Earth

7. Scale of the Universe SUN Mercury
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Mercury

8. Our Galaxy and Scale Our Milky Way galaxy is huge.
Let's now pretend that our galaxy is a kid's sandbox, and our sun is a grain of sand in a sandbox.
The Earth is a dust speck near the grain of sand, too small to be seen without a microscope.
If our sun were a grain of sand in this sandbox representing the Milky Way galaxy, the sandbox would be somewhat oval and yet flat, and would be about 20 feet in diameter.
The sand would be about 12 inches thick in the center, and thinner towards the edges.
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9. C. THE MILKY WAY GALAXY: Spiral Galaxy
Each swirling object you see is a galaxy in our universe.
1. We can estimate that there are about 100 billion stars in our galaxy.
2. Andromeda is the nearest major galaxy to our own Milky Way Galaxy.
3. Most scientists believe that Andromeda is about 2 million light years away from the Milky Way.
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10. D. Milky Way Galaxy: home to our solar system
D. Milky Way Galaxy: home to our solar system. Each point of light in the galaxy is a star.
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11. E. Distance in Space
Distance in space—mainly distance outside of our solar system—is measured in light years.
Example: distance to another star; which is a very, very, large distance
A light year is the distance light travels in a year, 5.88 trillion miles. IT IS NOT TIME!!!
3. Light travels at 186,000 miles per second.
4. If light from a star takes 15 years to reach us, the star is 15 light years away.
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12. F. An Astronomical Unit
1. The distance from the Sun to the Earth is 93 million miles.
2. 93 million miles = 1 astronomical unit
3. This is the unit of measurement for distances between planets in our solar system
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13. Astronomical Unit (AU) for the planets- 1AU = 93,000,000 miles
Average Distance from the Sun (measured in AU)
Mercury
0.39
Venus
0.723
Earth
1.0
Mars
1.524
Jupiter
5.203
Saturn
9.539
Uranus
19.18
Neptune
30.06
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14. G. The Sun: The STAR at the Center of Our Solar System
1. Wider than 100 Earths
2. 10,000 °F on surface & 27,000,000 °F in its core
3. less bright & massive than the very largest stars
4. Our sun is a medium sized star.
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15. Size in the Universe- Largest to smallest
Galaxy
Solar system
Star
Planet
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16. Quiz
1. How long does it take for the Earth to revolve around the sun one time? A. 245 days B. 445 days C. 365 days 2. What is the name of our galaxy? A. Milky Way B. Andromeda million miles = A. 1 light year B. 1 astronomical unit trillion miles= A.1 light year B. 1 astronomical unit 5. How long is Earth’s rotation? A. 1 day B. 1 month C. 1 year 6. What is at the center of our solar system? 7. What would we use to measure distances between stars in a galaxy? 8. What would we use to measure distances between planets in our solar system? 9. What do we call the study of the universe? 10. What do we call people who study and observe space?

17. The Inner Planets
Space Videos
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18. A. The Inner Planets: the terrestrial planets; all are dense & rocky
Mercury
Venus
Earth
Mars
5. The inner planets have fewer moons than the outer planets. Less mass = fewer moons.
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19. The Inner Planets’ Orbits
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20. B. Mercury- low mass No moons
resembles our moon because of all of its craters
no rings
closest to the sun
Big, grey rock made of iron
Smallest planet-fastest revolution in the solar system
Revolves around the sun in 88 days; Rotates on its axis every 58 days
Temperature variations on Mercury are the most extreme in the solar system.
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21. Mercury
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In Roman mythology Mercury is the god of commerce, travel and thievery, the Roman counterpart of the Greek god Hermes, the messenger of the Gods. The planet probably received this name because it moves so quickly across the sky.

22. C. Venus- low mass Earth’s twin—its size is almost as big as Earth
No moons; thick yellow clouds of acid, No rings
Dense nickel & iron planet w/a molten core; covered by many shield volcanoes (largest one is Sif Mons)
Hottest planet in solar system at 464°C due to its thick atmosphere
Atmosphere made of carbon dioxide (90%) & sulfuric acid, which creates a monstrous greenhouse effect.
Revolution: 243 days
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23. Venus
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Venus (Greek: Aphrodite; Babylonian: Ishtar) is the goddess of love and beauty. The planet is so named probably because it is the brightest of the planets known to the ancients. (With a few exceptions, the surface features on Venus are named for female figures.)
Venus has been known since prehistoric times. It is the brightest object in the sky except for the Sun and the Moon.

24. D. Earth- low mass
“Third rock from the sun,” made completely of rock; core made of iron & nickel;
1 moon—Luna, NO rings
Temperatures range from -13°C to 37°C
Densest planet in our solar system; has water in all 3 states of matter (solid, liquid,& gas)
5th largest planet in solar system
Revolution around the Sun is 365 days.
Only planet to sustain life.
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26. E. Earth’s Moon: Luna (384,400 km from Earth)
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Called Luna by the Romans, Selene and Artemis by the Greeks, and many other names in other mythologies.
The Moon, of course, has been known since prehistoric times. It is the second brightest object in the sky after the Sun. As the Moon orbits around the Earth once per month, the angle between the Earth, the Moon and the Sun changes; we see this as the cycle of the Moon's phases. The time between successive new moons is 29.5 days (709 hours).

27. F. Mars- low mass The red planet
Once had water on it; has polar ice caps that have both frozen water & carbon dioxide in them
Has 2 volcanoes—Tharsis (8,000 km wide) & Olympus Mons—an extinct shield volcano the largest volcano in the solar system
4. Temperature ranges: -123°C to 37°C
5. 2 moons: Phobos & Deimos (mean fear & panic)
6. Revolution: 1 year 322 days (687 days)
7. No Rings- borders the asteroid belt
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28. Phobos
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Phobos ("FOH bus") is the larger and innermost of Mars' two moons. Phobos is Greek for “fear.”Phobos is closer to its primary than any other moon in the solar system, less than 6000 km above the surface of Mars. It is also one of the smallest moons in the solar system.

29. Deimos
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Deimos ("DEE mos") is the smaller and outermost of Mars' two moons. It is one of the smallest known moons in the solar system.
In Greek mythology, Deimos is one of the sons of Ares (Mars) and Aphrodite (Venus); "deimos" is Greek for "panic".

30. Mars
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Mars (Greek: Ares) is the god of War. The planet probably got this name due to its red color; Mars is sometimes referred to as the Red Planet. (An interesting side note: the Roman god Mars was a god of agriculture before becoming associated with the Greek Ares; those in favor of colonizing and terraforming Mars may prefer this symbolism.) The name of the month March derives from Mars.

31. Mars—Home to the largest volcano in the solar system
Olympus Mons is the largest volcano on Mars. This shield volcano, similar to volcanoes in Hawaii, measures 624 km (374 mi) in diameter by 25 km (16 mi) high. It is 100 times larger than Mauna Loa on Earth. Located on the Tharsis Plateau near the equator, Olympus Mons is bordered by an escarpment. The caldera in the center is 80 km (50 mi) wide and contains multiple circular, overlapping collapse craters created by different volcanic events. The radial features on the slopes of the volcano were formed by overflowing lava and debris.
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32. Quiz Inner Planets Earth’s twin Looks like our moon Red Planet
Water in all 3 states
1 moon, Luna
Hottest planet
2 moons, Phobos and Diemos
Closest to the Sun
Largest volcano in the solar system
Massive greenhouse effect
Only planet to sustain life
Smallest planet
Greatest temperature difference, hot and cold
Revolution is 365 days
Fastest revolution around the sun
Quiz Inner Planets

33. Asteroids - rocks with sizes greater than 100m across
Most asteroids remain in the Asteroid belt between Mars and Jupiter but a few have orbits that cross Earth’s path.
Three asteroids hit the Earth every 1 million years!

34. Known asteroid impact sites

35. Asteroid sizes range from 100m to about 1000km
They are composed of carbon or iron and other rocky material.
The Asteroid belt is a group of rocks that appear to have never joined to make a planet. Why do we think this?
Too little mass to be a planet
Asteriods have different chemical compositions
It’s all Jupiter’s fault…..