The Solar System

1. The Solar System

2. The Solar System • A huge rotating system consisting of the Sun, eight planets and their satellites, dwarf planets, asteroids, comets, and meteors • Astronomers use the Nebular Theory to explain the formation of our solar system

3. The Nebular Theory • According to the nebular theory, our solar system began as a great cloud of dust and frozen gases • About 5 billion years ago this rotating cloud, known as a solar nebula, began to contract • As the nebula contracted, it spun faster and flattened itself into a disk shaped cloud • Compression of the matter in the center of the cloud ignited the hydrogen located there, forming the Sun • Gas and dust in the outer parts of the disk formed small asteroid like bodies called planetesimals. As these planetesimals collided, they grew larger, forming the planets

4. The Sun • The Sun accounts for 99.8% of the Solar System’s total mass • Due to its mass, the Sun exerts a powerful gravitational force • Force decreases rapidly with distance • Force strong enough to keep the planets and other distant object orbiting around the Sun

5. The Sun’s Interior • The Sun is a glowing ball of gas that has an interior and an atmosphere, but no solid surface • The Sun’s interior consists of the core, the radiation zone, and the convection zone • Core- the central region of the Sun, where nuclear fusion takes place • Radiation Zone-a region of tightly packed gas where energy is transferred in the form of electromagnetic radiation • Convection Zone-outer most layer of the Sun’s interior

6. The Sun’s Atmosphere • The Sun’s atmosphere includes the photosphere, the chromosphere, and the corona • Photosphere- the inner layer of the Sun’s atmosphere that gives off visible light • Chromosphere- middle layer of the Sun’s atmosphere • Corona- outer layer of the Sun’s atmosphere • Forms a halo around the Sun that’s seen during an eclipse • Thins to form a stream of charged particles called the solar winds

7. Features on the Sun • Features on, or just above the sun’s surface include sunspots, prominences, and solar flares • Sunspots- areas of gas on the Sun’s surface that are cooler and darker than the gases around them • Prominences- huge, reddish loops of gas that protrude from the Sun’s surface, linking parts of sunspot regions • Solar Flares- Eruptions of gas from the Sun’s surface that are produce when loops from sunspot activity suddenly connect

8. The Planets in the Solar System • The eight planets in the Solar System, named in order of increasing distance from the Sun are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, & Neptune • Astronomers use various criteria to group the planets

9. Inner vs. Outer Planets • The asteroid belt is used as a dividing line to separate the planets into two groups • The inner planets- Mercury, Venus, Earth and Mars (located between the Sun & the asteroid belt) • The outer planets- Jupiter, Saturn, Uranus, and Neptune (located beyond the asteroid belt)

10. Terrestrial vs. Jovian Planets • Terrestrial Planets- Planets that are Earth-like, in that they have a solid, rocky surface • Mercury, Venus, Earth, and Mars • Jovian Planets-Planets that are Jupiter-like, in that they have thick gaseous atmospheres that surround layers of liquid hydrogen and helium, and small rock and iron cores • Jupiter, Saturn, Uranus, and Neptune

11. Why the Inner & Outer Planets Differ • When the Solar System formed, temperatures were so high that most water and ice forming materials vaporized • The gravitational force of the inner planets wasn’t strong enough to capture most of the escaping hydrogen and helium gas • The outer planets, being in a cooler region, were able to grow in mass and capture much of the escaping gases

12. Rotation vs. Revolution • Rotation- The time it takes an object to spin once on it’s axis (a day on the planet) • Revolution- The time it takes to orbit another body in space ( a year on a planet)

13. Orbital Motion • A combination of inertia and gravity keep the planets in orbit around the Sun • Due to inertia, the planets want to move in a straight line which would take them away from the Sun • The Sun’s gravity pulls the planets toward it • The planets closer to the Sun orbit at a faster rate and have a shorter period of revolution than those farther away

14. Mercury • Closest planet to the Sun with an avg. distance = 58 million Km • Smallest Planet • Heavily cratered rocky surface (Looks like the moon) • Has almost no atmosphere or weather • Wide range of temperatures due to its slow rotation (-170°C to 430°C) • Period of rotation = 59 days 16 hours • Period of revolution = 88 days • No moons or rings

15. Venus • Avg. distance from the Sun = 108 million Km • Known as “Earth’s twin” due to its similar size, mass, density, and internal structure • Rocky surface featuring canyons, craters, plains, & volcanic mountains • The toxic atmosphere, composed of CO2 and droplets of sulfuric acid, is 90% heavier than Earth’s • The greenhouse effect produces an extremely high surface temperature (460°C) • Period of rotation = 243 days (retrograde) • Period of revolution = 225 days • No moons or rings

16. Earth • Avg. distance from the Sun = 150 million Km • Rocky surface, 70% of which is covered by water • Only planet that has water in all three states • Atmosphere composed primarily of nitrogen and oxygen • Surface temperatures range from -90°C to 58°C • Period of rotation = 24 hours • Period of revolution = 365 ¼ days • One moon, no rings

17. Mars • Avg. distance from the Sun = 228 million Km • About half the size of Earth • Red colored surface is rocky, heavily cratered, and features lava covered plains, deep canyons, huge inactive volcanoes, polar ice caps, and shows evidence of once flowing water • Thin atmosphere composed mostly of CO2 ,with small amounts of nitrogen, argon, oxygen, and water vapor • Temperatures range from -140°C to 20°C • Period of rotation = 24.5 hrs • Period of revolution = 1.88 years • Two moons, no rings

18. Jupiter • Avg. distance from the Sun = 779 million Km • Largest planet • Thick atmosphere composed of hydrogen, helium, methane, & ammonia • Huge storms, like the great red spot, swirl across the surface • Surface temperature = -148°C • Period of rotation = 10 hours • Period of revolution = 11.86 years • 63 moons and one thin ring

19. Saturn • Avg. distance from the Sun = 1434 million Km) • Swirling clouds produce a banded look • Atmosphere is stormy and composed of hydrogen, helium, methane, and ammonia • Ice particles and rocks form a series of rings around the planet • Average surface temperature = -178°C • Period of rotation = 10.5 hours • Period of revolution = 29.46 years • 56 moons, 7 major rings, & thousands of ringlets

20. Uranus • Avg. distance from the Sun = 2869 million Km • Gas giant that rotates on its side • Thick bluish-green atmosphere composed of hydrogen, helium, & methane • Avg. surface temperature = -216°C • Period of rotation = 16.8 hours (retrograde) • Period of revolution = 84 years • 27 moons and 9 narrow rings

21. Neptune • Avg. distance from the Sun = 4495 million Km • Bluish colored gas giant • Huge clouds of methane float in an atmosphere of hydrogen and helium • Avg. surface temperature = -214°C • Period of rotation = 16 hours • Period of revolution = 164.8 years • 13 moons and 4 rings

22. Other Objects in the Solar System • Dwarf Planets • Comets • Asteroids • Meteoroids • Moons • The Sun

23. Dwarf Planets • Pluto and any other round object that "has not cleared the neighborhood around its orbit, and is not a satellite" • Ceres is the only dwarf planet in the asteroid belt • Currently, there are three celestial bodies that have been redefined as dwarf planets (Pluto, Ceres, & Eris)

24. Comets • Loose collections of ice, dust, and small rocky particles that make long, narrow elliptical orbits around the Sun • There are three parts to a comet; the nucleus & coma (which make up the comet’s head), and the tail • The tail always points away from the Sun • Most comets originate in either the Kuiper belt (extends past Neptune) or the Oort Cloud(lies beyond Pluto)

25. Asteroids • Chunks of rock or fragments of planet-like material floating in space • Thought to be pieces of the early Solar System that never came together to form a planet • Most are irregular in shape and less than 1 Km long • Most revolve around the Sun in a narrow band, between Mars and Jupiter, called the asteroid belt

26. Meteoroids, Meteors, & Meteorites • Meteoroids- Chunks of rock, dust, or metal or stone in space - Most come from asteroids or comets that have broken up - About 100 million enter the Earth’s atmosphere daily • Meteors-Streaks of light produced when meteoroids burn up as they enter our atmosphere • Meteorites-Meteoroids that pass through the atmosphere and strike the Earth’s surface (Can produce craters)

27. The Origin of the Moon • The collision-ring theory is used to explain the moon’s origin • 4.5 billion years ago a planet-sized object collided with Earth to form the moon • Material from the collision was ejected into orbit around the Earth, forming a ring around the planet • Gravity caused this material to combine and form the moon

28. Characteristics of the Moon • The moon is barren and airless • Avg. distance from Earth = 384,000 Km • Approximately ¼ the size of the Earth and has about 1/8 the mass of Earth • Due to it’s lack of atmosphere, the moon has a wide range of temperatures, ranging from -180ºC to 130ºC • Although there is no liquid water on the surface, evidence suggests that there may be ice near the poles as well as liquid water reserves deep below the surface

29. Features of the Moon’s Surface • Maria- Dark, flat areas on the moon’s surface formed from huge ancient lava flows that occurred 3 to 4 billion years ago • Craters- Large round pits caused by the impact of meteoroids • Highlands- Light-colored mountainous regions covering much of the moon’s surface

30. Movement of the Moon • Revolves around the Earth in a counter-clockwise direction • Rises in the east and sets in the west (about 50 minutes later each day) • Period of revolution and rotation are both 27.3 days (Causes the same side of the moon to always face the Earth) • The changing relative positions of the moon, Earth and the Sun cause the phases of the moon, eclipses, and tides

31. The Moon’s Phases • The relative motions of the Earth, Moon and Sun cause a change in the moon’s appearance • The Sun lights up the half of the Moon that faces it • The phase of the moon seen depends on how much of the sunlit side of the moon faces Earth • The daily changes in the Moon’s appearance are called phases • Lunar month- Time from one new moon to the next (about 29.5 days)

32. Phases of the Moon

33. Waxing Phases When the moon appears to grow larger as it goes from being a new moon to a full moon • New moon • New crescent • First quarter • New gibbous • Full Moon

34. Waning Phases When the moon appears to grow smaller as it goes from the full moon phase to the new moon • Full moon • Old gibbous • Last quarter • Old crescent • New moon

35. Eclipses • Occur when one object in the sky is blocked from view by another • Named for the object that we don’t see • During an eclipse, the shadow of one object falls on the other • The shadow has two parts, a dark inner shadow (umbra) and a lighter outer shadow (penumbra) • Being in the umbra produces a total eclipse, while being in the penumbra, a partial eclipse

36. Lunar Eclipse Blocking of the moon that takes place when Earth comes directly between the Sun and the full moon

37. Solar Eclipses Blocking of the Sun that occurs when the new moon comes directly between the Sun and the Earth

38. Tides • Tides are the rise and fall of ocean waters that occurs about every 12 ½ hours • Tides are caused mainly by differences in how much the moon’s gravity pulls on different parts of the Earth • At any one time there are two places with high tides and two places with low tides • One high tide will be on the side of Earth facing the moon and the second will be on the opposite side • Low tides occur at locations between the high tides

39. The Sun’s Influence on Tides Although the moon is the main factor causing the tides, the influence of the Sun’s gravity on Earth’s oceans is seen during spring tides and neap tides

40. Spring Tides and Neap Tides • Spring tides- have the greatest difference in height between high tide and low tide (tidal range) • Produces the highest high tides and the lowest low tides • Occurs when the Sun and moon align with Earth during a new moon or a full moon • Neap tides- have the smallest tidal range • Produce the lowest high tides and the highest low tides • Occurs when the gravity of the Sun and the moon pull at right angles to one another during the moon’s first and third quarter phases