# THE SOLAR SYSTEM What is GRAVITY n Gravity

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THE SOLAR SYSTEM

What is GRAVITY ? n Gravity is the universal attraction between 2 objects…it’s the force that pulls 2 objects towards each other. n Two factors of gravity: 1. Mass – the more massive an object, the more gravity pull 2. Distance – The further the distance between 2 objects, the less gravity pull

Factors of gravity. MASS DISTANCE 90 x 1023 Kg More gravity pull n Less gravity pull 3 x 1023 kg Less gravity pull

Gravity Equation Mass of 1 st object Force of Gravity Mass of 2 nd object Gravitational constant # Distance between objects 2

Why does mass matter? n Why do objects with more mass have higher gravity pull? n New thinking (Albert Einstein) states that space is like fabric…more massive objects in space causes larger depressions. More massive the object in space = deeper the fabric funnel = more objects pulled down towards it…(GREATER GRAVITY)

Curved Space Some objects in space are so massive that their gravity pull can alter or bend light radiation. A star that you are looking at in the night sky may not be straight ahead of you…crazy !

Mass vs. Weight n Mass – The amount of matter that makes up a substance. Mass of an object stays the same unless you add or subtract matter. n Weight depends on how much gravity pull something has n More gravity = higher weight

Refracting Telescope OBJECTIVE LENSE (gathers light) EYE PIECE PRISM / MIRROR (refract light)

Reflecting Telescope OBJECTIVE MIRROR CONCAVE (gathers light) EYE PIECE DIAGANOL MIRROR (REFLECTS LIGHT)

Our Star…the Sun SUN

Interior of Sun’s Core (nuclear fusion) Radiation Zone Convective Zone

Interior of Sun n The Sun seems to generate its energy in its core from a process called nuclear fusion. n Nuclear Fusion – hydrogen (H) particles are under so much pressure, that they join together to make helium (He). This process releases enormous amounts of energy in the core. H² Escaping energy He H³

Sun’s Surface PHOTOSPHERE (skin of Sun) Consists of: • Sunspots • Granules • Prominences • Solar flares

Closer look at Photosphere Granules (bubbles of gas & plasma) Sunspot (cooler area of gas) Solar wind Prominence (Magnetic attraction of plasma near sunspots) Solar flare (massive amounts of energy explodes from surface…near sunspots)

Sun’s Corona - The Sun’s atmosphere made of gases and plasma that extends millions of kilometers into space

Interesting facts about the Sun n Only star in our Solar System. The Sun is 99. 8% of the total mass of the Solar System. By far the biggest object in our Solar System Diameter = 109 Earth’s straight across!! n Volume = 1, 200, 000 Earths (could fit inside)!! n n n The Sun is where 99. 9% of all energy comes from. Temp. = 10, 000˚F to 27 million ˚F at the core.

Sunspots give scientists an idea of the amount of activity coming from the Sun. More sunspots = more activity.

Frequency of Sunspots The frequency of maximum to minimum sunspots seems cycle every 10 – 11 years.

SOLAR WIND (magnetic storms) CME (ejects more energy than normal in a direction, along with charged particles) North (+) & South (-) Poles create a magnetic field around Earth, protecting us from harmful solar wind Solar Wind EARTH

Auroras. When some charged particles from Sun make it through our magnetic field…they interact with our magnetosphere & atmosphere…causing magnetic storms and auroras in the Northern & Southern skies. Magnetic storm Solar Wind

Auroras

How do we know the Earth is curved? n Before people had the technology we have today, they had to find alternative ways to figure this out. 1. Shadows were seen on Earth in different places at the same time, but at different angles. 2. Looking at a ship sail out to sea, we notice it seems to sink over the horizon. The boat follows the curve of Earth.

Flat Earth vs. Spherical Earth SUN Flat Earth SUN Sphere If Earth were flat, at noon all the sun’s energy would hit the surface at the same angle. Since Earth is a sphere, the Sun’s energy hits the surface at different angles…causing differential heating

What Causes Day and Night? Earth is a sphere. Therefore, half of the Earth is illuminated at all times. • The side facing the Sun experiences day • The side facing away from the Sun has night. Day Night

What causes Day / Night continued… • Earth rotates (spins) on its axis. • This allows sunlight to shine on different parts of Earth. • Earth rotates once every 24 hours = 1 Day

Time change as Earth rotates 12 noon 12 midnight 6 pm 6 am

Earth’s Revolution Earth revolves (orbits) around the Sun once every 365 ¼ days = 1 year. Every 4 th year a day is added…LEAP YEAR. Autumn Winter Summer Elliptical orbit (oval) Spring

a) Energy travels further distance through atmosphere and is more indirect so spreads out = cooler temps. b) Energy travels less distance through atmosphere and is more direct so is less spread and more concentrated = warmer

What Causes Seasons on Earth? 1) Earth’s spherical shape causes energy to hit at different angles causing direct or indirect sunlight. 2) Earth is titled at 23. 5 ˚ on its axis 3) Since Earth revolves around the Sun, some places get direct and indirect sunlight at different times in the orbit. Anywhere above or below the equatorial region has seasons (23. 5 degrees N or S latitude)

Seasons continued… Northern hemisphere tilted toward the Sun = more direct sunlight = longer days = higher avg. temps.

Seasons continued… Northern hemisphere tilted away from the Sun = less direct (indirect) sunlight = shorter days = lower avg. temps.

Direct 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 energy Direct = focused on smaller area = more intense energy

If Earth had NO Inclination (tilt) If Earth had NO tilt, then the Sun’s energy would always hit at the same angle at places, thus causing no difference in temp. throughout the year.

Earth’s Inclination (tilt) Earth is tilted. So when it revolves around the Sun, the angle of energy changes throughout the year. This is how we come to understand seasons. 23. 5º Tilt RE HE P S O ATM

Direct vs. Indirect Sunlight

Seasons on Earth revolves (orbits) the Sun avg. speed of 70, 000 mph. n 1 orbit takes about 365 ¼ days. n Earth’s orbit is not a circle, it is elliptical (oval). n n Elliptical orbit causes Earth’s distance from Sun to vary. n Aphelion n Perihelion Tilt of Earth causes seasons!!! Not distance from Sun.

Sunlight’s path through our Atmosphere n Because Earth is curved and tilted, this causes sunlight to pass through varying amounts of Earth’s atmosphere.

How does the moon stay with Earth? Earth’s gravity pull is greater than the Moon’s and has trapped it for billions of years!! n Earth pulls on the moon more than the moon pulls on Earth. (Earth is more massive = greater gravity). Moon is ¼ the siz of Earth.

What if… n If moon was not moving, Earth’s gravity would pull it in! n. If Earth did not have gravity, the moon would fly out into space! (Law of Inertia) EARTH MOON

What is the Law of Inertia? n n This is Newton’s 1 st Law of Motion. Law of Inertia states: 1. An object in motion will stay in that same motion (direction & speed) until change is caused by an outside force. 2. If an object is at rest, it will remain at rest until an outside force acts upon it…puts it in motion.

Centrifugal Motion n n Since 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.

Cont… n 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!

Our Moon n n Earth’s Moon is its only natural satellite. Moon is caught in Earth’s gravity pull. Moon’s orbit is on avg. 240, 000 miles from Earth. Sun’s light reflects off the Moon for us to see. Moon is about ¼ the size of Earth.

Moon’s Motion n Rotation - The Moon spins on its axis once every 27 1/3 days. Revolution – It also takes 27 1/3 days for our Moon to orbit Earth once. Same side always faces Earth!

Why we get Phases of the Moon. From space, half the moon is always illuminated by the Sun. n From Earth we see a change in illumination (phases) because of the angles between the positions of the Sun, Moon, and Earth. n

Moon Phases Diagram What we see from Earth SUN View from space

No atmosphere to protect from space rocks (asteroids) Dark areas are dried up lava beds

Period of Phases To go from one phase back to the same phase takes about 29 ½ days…which is 2 days longer than its revolution time. WHY? While the moon orbits Earth…Earth is still moving. It takes 2 more days for the Sun, Moon, and Earth to get back to the same angle.

Eclipses of the Moon n The Moon revolves (orbits) Earth once every 27. 3 days. Its path around Earth is not on a straight, even plane. Moon’s orbital path is slanted. n Once in a while, the moon will pass directly in front or behind the Earth! n Solar Eclipse n Lunar Eclipse

Solar Eclipse n Sometimes the moon passes directly in between the Earth & Sun. The moon casts a shadow on parts of Earth.

Lunar Eclipse n Sometimes the moon goes directly behind Earth into its shadow. Most light cannot reflect off the moon. Red and orange frequency of light bends around Earth to give the moon a bloody color when this happens.

What are tides? n Tides are the rise & fall of sea level near a coastline. Since Earth rotates so fast we experience four tides everywhere per day! n 2 High Tides n 2 Low Tides

Moon & Tides n The 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.

Spring & Neap tides n Neap Tide Difference b/w high & low tides are small. n Occur during the 1 st & 3 rd quarter moons Spring Tide Difference b/w high & low tides are greater. Occur during the New and Full moons

Moon & Earth’s Rotation n The dynamics between the Earth’s waters and the Moon’s gravity pull slows Earth’s rotation.

n Causes 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. n n n 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 climate Earth is curved (sphere) n This causes sunlight/energy to pass through different thicknesses of atmosphere n n The 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)

Early Astronomy n Ancient Greeks noticed a pattern in star movement… n Stars gradually moved across the sky in a circular motion, star patterns stayed the same. n Greeks noticed 5 points of light wandering among the stars. n Greeks called these “planets” meaning to wander.

Geocentric System Greek astronomers believed Earth was center of universe Everything revolved (orbit) around Earth. Greek astronomer “Ptolemy” 140 A. D. explained motion of planets by celestial phenomena. He backed the Greeks belief of a Geocentric System.

Ptolemy’s Geocentric System Earth Centered Solar System (not true!!!)

Heliocentric System Astronomer Copernicus n Early 1500’s (1, 400 years after Ptolemy) n He believed planets revolved around Sun. (Heliocentric) n He used mathematics to help prove (against belief from Catholic Church)

Heliocentric System… n Galileo Galilei – n Used the modern telescope in 1609 to observe other planets and moons in more detail. n He supported Copernicus’s Heliocentric Theory: n 1) Viewed Jupiter’s Moons n 2) Viewed phases of Venus

Heliocentric System Sun Centered Solar System

Orbital Motion & Speed n n n The Sun is considered the “center” of our Solar System. All other planets revolve around the Sun…this is known as the planet’s orbit (year). Planets do NOT orbit in a perfect circle. They orbit in an elliptical shape (oval).

Speed of orbit n n The closer a planet is to the Sun, the faster its orbit. This is due to increased gravity pull! n Closer the objects = greater gravity. Earth 365 ¼ days MARS 687 days Venus 225 days Mercury 88 days

Gravity vs. Inertia n Inertia – tendency of an object to remain in motion or at rest until an outside force acts upon it. (1 st Law of Motion) n Gravity – The inward pulling force an object possesses. Depends on mass & distance between objects.

In this case… n In this case, the planets want to go straight (inertia) at a certain speed, but the Sun’s gravity is pulling it at the same time. This causes planets to revolve around the Sun.

Gravity vs. Inertia Planet wants to go Straight. (Law of Inertia) SUN Sun’s Gravity Pull Planet

Impact Craters Circular depression on a surface, usually referring to a planet, moon, or large asteroid, caused by a collision of a smaller body (meteor) with the surface. Barringer Crater (0. 8 miles diameter)

Wolf Creek Crater n About ½ mile in diameter

Simple Crater n Bowl shaped form, mostly surrounded with smooth walls. This type of crater has a diameter less than 9 miles.

Complex Crater n Have single or multiple peaks inside the crater. Diameters range from 12 to 110 miles!! n The “central peak uplift” is caused by recoil of the surface…springing up action like rain hitting a pond in slow motion.

Terrestrial Planets Size to scale…distances not. Terrestrial planets consist of the first 4 planets (Mercury, Venus, Earth & Mars). n “Earth-like”, small, rocky surface, with a solid inner core. n

Mercury n n n Closest planet to the Sun. Now considered smallest planet (not Pluto) Quickest revolution of any planet (88 Earth days). No moon (satellite) Has very little to no atmosphere. Rotates very slow (1 day = 59 Earth days). n Has time to heat up to 842 F during the day. n Cool down to -292 F at night. (heat energy escapes easily with small atmosphere)

Why no steady atmosphere on Mercury? Because Mercury rotates so slowly and is so close to the Sun, its surface heats up to extreme temps. during the day (29 days) that the exposed rocks begin to turn into a gas (atmosphere). But the gases quickly escape to space due to its low gravity pull.

Mercury Pictures Satellite pics Missing pics from satellite Craters on surface

Size comparison (not in correct order!!) Earth Mercury Our Moon

Venus “Goddess of Beauty”

General knowledge n n n Venus is the 2 nd planet from the Sun. Just a little smaller than Earth (similar in size). Hottest planet in our Solar System. No natural satellites (moons). Rotates the slowest n n One full day is longer than one full year!! Spins in opposite direction than other planets 3 rd brightest object in our sky (next to the Sun & moon) Sun’s light reflects brightly off of Venus’ clouds.

Venus’ violent surface! Surface of Venus is very hot, close to 900˚F ! n No water on surface, barren land. n Venus has active tectonic activity n Earthquakes n Volcanic eruptions that spew molten rock (lava). n volca no

Pictures of Venus n cloud cover below clouds

Venus’ violent atmosphere! 96% of the air on Venus is Carbon Dioxide (poisonous gas)! n Has crushing air pressure… n The clouds that cover the surface are made of sulfuric acid (rains acid) n These clouds reflect 80% of the sunlight n About 20% get through. n The heat that gets through is then trapped. “Greenhouse effect” n

Greenhouse Effect n Some sunlight gets through the clouds, but the carbon dioxide in the air traps the heat!! Like Very little heat an oven!! escapes. Most light reflects off clouds back to space. Some gets through Different wavelengths of heat come off surface but can’t escape!

Earth: 3 rd rock from the Sun

Earth facts n n n Only planet in Solar System to harbor life as we know it. Only planet that has water in all 3 phases (liquid, gas, solid) Largest of the Terrestrial planets 1 natural satellite (our moon) Thick atmosphere (about 400 miles above surface) n 78% nitrogen n 21% oxygen

Earth’s Atmosphere

Parts of atmosphere Troposphere – 0 to 10 miles above the surface of Earth. n Stratosphere – stretches from 10 -30 miles above surface. (ozone layer – absorbs harmful radiation from the Sun). n Mesosphere – Stretches from about 30 -50 miles above surface n Thermosphere – 50 to 400 miles above surface. n n Extremely high temps. , up to 3, 000 F.

MARS n 4 th Planet from the Sun. Deimos Phobos

Mars Facts About ½ the size of Earth n Has 2 natural satellites (moons) n Commonly known as the “Red Planet”. Looks rusty from far away. n Much of the crust of Mars is rich with ironoxide (rust) from metal & water combining. n This is one reason we think Mars may have once had liquid water. n n Mars has water in the solid, gas, and possibly the liquid phase.

Mars cont… n n Has a thin atmosphere – 95% carbon dioxide (poisonous). Mars is on average very cold (-81 F) on surface. Known to have huge wind / sand storms. Two unique geological features. 1. 2. Valles Marineris – huge canyon that stretches over 2, 500 miles!!! Olympus Mons – Volcano 3 X higher than Mt. Everest

Olympus Mons Dormant volcano (not active) n About 15 miles high!! n

Valles Marineris Canyon could stretch almost across the U. S. n Grand Canyon is a dwarf compared to this! n

The Jovian Planets (Gas Giants) n Jupiter n Saturn n Uranus n Neptune

Jupiter

n 5 th n n n Jupiter planet from our star (The Sun) Largest of all the planets!! 60 + natural satellites revolve around Jupiter! n Like a mini solar system… Planet is gaseous with ice crystals n Mostly hydrogen gas n “Great Red Spot”, which is a massive storm 3 x the size of Earth wind speeds hundreds of mph!! Very far from Sun, very cold! Has a small ring system not easily seen.

Saturn

n n n Saturn 6 th planet from the Sun 2 nd largest planet in our Solar System 50+ known natural satellites (moons) n Titan – this Mercury sized moon has an atmosphere similar to that of a “young Earth”. Highly studies by scientists!! Made of gases & ice crystals. n Mostly hydrogen gases Extravagant ring system!!! Kept in by its gravity pull. n Rings are mostly pieces of space rock (some small, some large) Extremely cold planet!!

URANUS

n n n n URANUS 7 TH Planet from the Sun Furthest planet that can be seen without a telescope. Tilted on its axis at 98 degrees. Blue-green color is a result of the methane in the upper atmosphere. n Methane absorbs red light. Mostly gas planet, some liquid & ice n Hydrogen (mostly) 27 known natural satellites. Very cold planet, with strong winds whipping around.

NEPTUNE

NEPTUNE n n n 8 th and last planet in our Solar System. Known as Uranus’ twin. Made of gases, liquids, and some ice. (no surface) Gets its bluish color from methane gas. Has 13 known natural satellites n n Hurricane-like winds up to 700 mph! n n Triton – largest satellite Strongest winds ever recorded in our Solar System. Very cold planet

PLUTO Charon (moon) n n n Not considered a Planet n Does not dominate its orbit…little gravity pull. Known as a ‘Dwarf Planet’ (new category) Very small, rocky, cold, and desolate planet. No atmosphere. Slightly smaller than Earth’s Moon! Has a small moon - Charon

Pluto size comparison Earth Pluto & Charon Our Moon n Earth…Pluto & moon Charon…Earth’s Moon.

Unusual orbit For 20 years out of its 250 year orbit, Pluto is NOT the furthest planet.

Asteroids, Meteors & Comets n An asteroid is a large space rock (probably remains of a broken up planet) located usually between the orbits of Mars & Jupiter. Asteroids can be miles wide!! n Asteroids sometimes hit each other and fly in different directions…sometimes these lost asteroids hit planets, causing massive collisions…craters. n Asteroid Size of truck = Asteroid 1 mile wide

Meteors n When asteroids break apart into smaller pieces, they are commonly called meteoroids. n Meteoroid – When an asteroid or comet breaks up into smaller pieces and the debris flies erratically through space. Meteor – When a meteoroid enters Earth’s atmosphere, friction causes it to burn up and streak through the sky. n “ shooting stars” n Meteorite – Meteors that don’t fully burn up as it passes through the Earth’s atmosphere and hits the surface…causing a meteor crater.

Comets n Comets are chunks of ice and dust (think of a dirty snowball) that orbit our Sun in very long, narrow elliptical orbits. Very long elliptical orbits around our Sun. The tail of the comet is ice turning to gas and the Sun’s solar wind pushes it away.

Parts of a Comet Tail Nucleus Coma

The Big Bang Theory n Theory that all energy and matter that makes up our world, solar system & universe started from an explosion of a single, infinitely dense point. The formation of space and time began!

Proof of the Big Bang Theory n Stars and galaxies are expanding (getting further from each other) and cooling. If this is the case, it suggests that the universe must have once been smaller & hotter (point of singularity). n Measuring light. & understanding visible

Matter Condenses n n As little as 100 million years after the Big Bang, matter started to condense upon itself. Forming nurseries of star birth known as Nebulas… The more matter that came together, the more gravity pull…the more gravity pull, the higher the pressure = higher temperatures! Once temperatures were high enough for nuclear fusion…stars were born! Nebula consisting of millions of stars.

Formation of Galaxies n As matter (gases & particles) condensed, stars were born. These stars and gases started to revolve around a center point (galactic center) of high gravity pull. 3 types of galaxies… Spiral galaxy Elliptical Irregular

How big are Galaxies? n n Galaxies are clusters of stars just like our Sun…some bigger, some smaller. One galaxy can be made up of 100’s of billions of stars!!! In order to understand size, we need to use light year units.

Formation of Solar Systems n n Within galaxies, matter (dust & particles) started to swirl around many stars! Over time, this matter may have condensed together to form planetary bodies that revolve around a star. This is known as a Solar A star with matter System. swirling around it The matter condenses to form planetary bodies

Galactic Address n Redding Middle School

Middletown, DE

Delaware Middletown

North east, USA

United States

Earth Delaware

Our Solar System EARTH

Galactic Arm (Orion Arm)…millions of stars!!! Our Solar System

Milky Way Galaxy…billions of stars!!! Our Solar System

Galaxy Cluster (Local Group)