Presentation on theme: "8th Grade (adapted by Mrs. Hubbard)"— Presentation transcript:
18th Grade (adapted by Mrs. Hubbard) Solar System8th Grade(adapted by Mrs. Hubbard)
2What causes Day / Night? Earth’s rotation (spin) Earth rotates on its axis (imaginary line through the north and south poles).It takes about 24 hours to make one complete rotation.At any one time, half the Earth is illuminated by the Sun.
3Flat Earth vs. Spherical Earth SUNIf Earth were flat, at noon all the sun’s energy would hit the surface at the same angle.Flat EarthSince Earth is a sphere, the Sun’s energy hits the surface at different angles…causing differential heatingSUNSphere
4Direct vs. Indirect Sunlight Because of Earth’s spherical shape, the light that reaches from the Sun hits at angles. These angles of light are known as either: Direct or Indirect sunlight.Indirect = more spread = less intense energyDirect = concentrated = more intense energy
5If Earth had NO Inclination (tilt) If Earth had NO tilt, then there would be no seasons throughout the year & each day would be an equinox (12 hours of light & 12 hours of night)
6Earth’s Inclination (tilt) Earth IS tilted (inclined) which helps cause the seasons and different amounts of day and night throughout the year.23.5º inclinationATMOSPHERE
7Earth’s RevolutionEarth revolves (orbits) around the Sun once every 365 ¼ days = 1 year. Every 4th year a day is added…LEAP YEAR.AutumnWinterSummerElliptical orbit (oval)Spring
8What Causes SeasonsCombination of Earth’s tilt (differential heating of surface) & revolution (orbit) around the Sun causes seasons.NOT DISTANCE FROM SUN!!Northern hemisphere tilted toward the Sun = more Direct Sunlight = SummerNorthern hemisphere tilted away from Sun = Indirect Sunlight = Winter
9How does the moon stay with Earth? Earth’s gravity pull is greater than the Moon’s and has trapped it for billions of years!!Earth pulls on the moon more than the moon pulls on Earth. (Earth is more massive = greater gravity).Moon is ¼ the sizeof Earth.
10What if… If moon was not moving, Earth’s gravity would pull it in! If Earth did not have gravity, the moon would fly out into space! (Law of Inertia)EARTHMOON
11What is the Law of Inertia? This is Newton’s 1st Law of Motion.Law of Inertia states:An object in motion will stay in that same motion (direction & speed) until change is caused by an outside force.If an object is at rest, it will remain at rest until an outside force acts upon it…puts it in motion.
12Centrifugal MotionSince the Earth’s gravity is present, and the moon is in motion (tries to go straight, but can’t), it starts a circular path around Earth (orbit / revolution).This revolution around Earth causes an outward pull (Centrifugal Motion) which counters the inward pull of gravity.
13Cont…This constant inward pull from gravity, along with the constant outward pull by the moon’s centrifugal motion eventually reached a point of equilibrium some 4.5 billion years ago…ever since, the moon has been our closest neighbor!
14Our Moon Earth’s moon is its only natural satellite It is about ¼ the size of Earth.It’s average distance from Earth is about 230,000 miles (if you were traveling 60 mph in a car from Earth to the Moon, it would take about 5 months!!)The moon does NOT generate its own light…the Sun’s light reflects off of it.
15Moon’s MotionRotation – The Moon spins on its axis once every 27.3 days (1 day = 27.3 Earth days)Revolution – The Moon goes around the Earth every 27.3 days (1 year = 27.3 Earth days)Full Moon to Full Moon = 29.5 days…?
16Why we get Phases of the Moon. From space, half the moon is always illuminated by the Sun.The moon is a sphere, so the light coming from the Sun can only illuminate half of it at one time.From Earth, we see shadows (phases) because of the angles between the positions of the Sun, Moon, and Earth.
17Moon Phases DiagramSUNWhat we see from EarthView from space
18Eclipses of the MoonThe Moon revolves (orbits) Earth once every 27.3 days. Its path around Earth is not on a straight, even plane.Once in a while, the moon will pass directly in front or behind the Earth!Solar EclipseLunar EclipseMoon’s orbitalpath is slanted.
19Solar EclipseWhen the moon passes directly in between the Earth & Sun. The moon casts a shadow on parts of Earth.Sun notto scale
20Lunar EclipseWhen the moon passes directly behind the Earth and the Earth is blocking the Sun’s light from reflecting off the moon.
22Moon & TidesThe Moon does pull Earth some with its own gravity. Its pull is less than Earth’s so it does NOT affect the solid surface…but it does affect Earth’s oceans.
23What are tides?Tides are the rise & fall of sea level near a coastline. Since Earth rotates so fast we experience four tides everywhere per day!2 High Tides2 Low Tides
24Spring & Neap tides Neap Tide Spring Tide Difference b/w high & low tides are small.Occur during the 1st & 3rd quarter moonsDifference b/w high & low tides are greater.Occur during the New and Full moons
25Moon & Earth’s Rotation The dynamics between the Earth’s waters and the Moon’s gravity pull slows Earth’s rotation.
26Seasons on EarthEarth revolves (orbits) the Sun avg. speed of 70,000mph.1 orbit takes about 365 ¼ days.Earth’s orbit is not a circle, it is elliptical (oval).Elliptical orbit causes Earth’s distance from Sun to vary.AphelionPerihelionTilt of Earthcauses seasons!!!Not distance from Sun.
28Sunlight’s path through our Atmosphere Because Earth is curved and tilted, this causes sunlight to pass through varying amounts of Earth’s atmosphere.
29Causes of Seasons on Earth (recap) Earth is tilted on its axis at 23.5 degrees. As Earth revolves around the Sun, different parts of Earth receive varying sunlight intensity.Direct sunlight – Sunlight/heat is more concentrated on an area of land – more intense – warmer climate.Indirect sunlight – Sunlight/heat is more spread out, has to distribute energy to more land – less intense – cooler climateEarth is curved (sphere)This causes sunlight/energy to pass through different thicknesses of atmosphereThe more atmosphere light has to pass through, the less intense it is = cooler weather (climate)The less atmosphere light has to pass through, the more intense it is, = warmer weather (climate)