Module 3 The Solar System

3.01 Historical Solar System Models The early models of the solar system were based on philosophy and religion. Philosophers spent their time discussing and debating how the universe looked. We must remember: Philosophers did not have the technology that we have today. The origin and placement of the Earth were deeply rooted in religion. Recall, philosophy and religion fall under pseudoscience. As you work through this lesson, keep an eye out for views of the universe that are considered pseudoscience.

3.01 Historical Solar System Models The geocentric model is the theory that states: The Earth is the center of the universe. All of the other objects in the universe go around the Earth. All objects orbit the Earth in perfect circles because all things in the heavens are perfect.

3.01 Historical Solar System Models The geocentric model was accepted until the 16th century. The geocentric model was based on philosophical views, religious views, and two observations that were thought to be true: Objects in the sky seemed to move around the Earth each day. The Earth’s movement could not be felt.

3.01 Historical Solar System Models The heliocentric model is a theory that states: The sun is the center of the universe. All objects in the universe orbit around the sun in perfect circles. The Heliocentric model was based on Nicolas Copernicus’ use of mathematical evidence to prove the planets and earth revolve around the sun.

3.01 Historical Solar System Models Review Heliocentric View: Sun is the center of the universe. Based on science. Both: Objects orbit in perfect circles. Geocentric View: Earth is the center of the universe. Based on pseudoscience.

3.02 Current Solar System Model The Sun The sun is the star in our solar system that provides warmth and light to the planets. The Planets Planets are objects that orbit a star. A planet is massive enough to have gravity of its own but not massive enough to ignite. Moon Moons are objects that orbit planets. Comet One of the small objects in our solar system that orbit the sun.

3.02 Current Solar System Model All objects in our solar system orbit around the sun or planets. It was once thought that these orbits were a perfect circle; However, it has since then been shown that the orbit of these objects are in the shape of an ellipse.

3.02 Current Solar System Model Planets revolve around the Sun. In this type of orbit, the planets move around the Sun in the shape of an ellipse. Gravity is what causes the planets to move around the Sun.

3.02 Current Solar System Model Moons revolve around planets. This type of orbit is very similar to how planets move around the sun. In this case, the moon revolves around the planet. The moon also moves around the planet in the shape of an ellipse. Again, gravity is what causes the moon to move around planets.

3.02 Current Solar System Model Comets revolve around the Sun. In this type of orbit, a comet revolves around the sun in a long ellipse. Once again, gravity is what causes comets to move around the sun.

3.02 Advanced - A Journey Through Our Solar System Welcome to your journey. We are going to visit all of the objects in our solar system. The sun provides all heat and light for our solar system. Some parts of the sun can get to 15,000,000 °C. Did you know that the sun makes up 99.8% of the Solar System’s mass? Think of mass as how much “stuff” there is in our solar system.

3.02 Advanced - A Journey Through Our Solar System Mercury is the smallest planet in the solar system. It is also the closest planet to the sun. Because Mercury is so close to the sun, Mercury becomes very hot during the day; however, it also becomes very cold during the night. Mercury has a similar appearance as our moon; it is full of craters.

3.02 Advanced - A Journey Through Our Solar System Venus is the second planet from the sun. Other than the moon, Venus is the brightest object in the night sky. Venus is sometimes called Earth’s sister planet because Earth and Venus have about the same size and amount of gravity. Venus is covered with a layer of clouds that make it impossible to see its surface without a special telescope.

3.02 Advanced - A Journey Through Our Solar System Earth is the third planet from the sun. It is ideally suited for life. Mars, the fourth planet from the sun, is a reddish color which is a direct result of its iron content. Mars is thought to possibly have water. Since water is necessary for life, some scientists think that Mars could possibly hold life. We have sent many probes to Mars to obtain samples and study the planet.

3.02 Advanced - A Journey Through Our Solar System Jupiter is the fifth planet from the sun. Jupiter is also the largest. If you were to add up all of the other planet’s masses, Jupiter would still be almost three times bigger! Jupiter is the first of the gaseous planets. That is it is made up mostly of gas. Jupiter is mostly famous for its giant red spot. Jupiter’s spot is caused by a huge storm on the surface of the planet. This spot is big enough for three Earths to fit inside.

3.02 Advanced - A Journey Through Our Solar System Saturn is the sixth planet from the sun. It is also the second largest planet. Saturn is most famous for its rings. These rings are made of dust and ice that orbits the planet. Saturn’s rings can be seen with an average telescope or a good pair of binoculars. Like Jupiter, Saturn is also a gaseous planet.

3.02 Advanced - A Journey Through Our Solar System Uranus is the seventh planet from the sun. Uranus is the farthest planet that we can see without a telescope. If you look for Uranus on a clear night, you may be able to see it without a telescope. Uranus’s most distinct feature is it rotates completely on its side. Like Saturn, Uranus also contains rings, but they are not at distinct as Saturn’s. Uranus contains a large amount of ice; however, Uranus is also considered a gaseous planet.

3.02 Advanced - A Journey Through Our Solar System Neptune is the eighth and last planet from the sun. Neptune has a similar composition to Uranus because it contains a large amount of ice. Neptune is also considered a gas planet. Pluto was recently downgraded from a planet to a dwarf planet. Dwarf planets are planets that do not have enough gravity to clear everything in their path. Pluto is so far away that it is hard to get a clear image of what it actually looks like.

3.03 The Seasons What Causes the Seasons? The seasons are caused by: the position of the Sun the position of the Earth the tilt of the Earth on its axis

3.03 The Seasons Notice how the top part of the earth is leaning toward the sun, which means it receives more of the sun’s energy. Here, the top part of the earth is leaning away form the sun, meaning it receives less energy from the sunlight.

3.04 Phases of the Moon Phases of the Moon Misconceptions Remember how there were some common misconceptions for what caused the seasons. There are just as many misconceptions about what causes the phases of the Moon. Many people mistakenly think that the phases of the Moon are caused by the Earth casting a shadow on the moon. This is not true. Although the Earth does cast a shadow on the moon during a lunar eclipse, the phases of the Moon have nothing to do with shadows.

3.04 Phases of the Moon What causes the phases of the Moon? There are a few items that you should know before you can understand what causes the phases of the Moon: The Moon revolves around the Earth. Only half of the Moon is lit by the Sun. On Earth, we can only see the lit part of the Moon. Only half of the Moon faces the Earth at one time. As the moon revolves around the Earth, the side of the moon that faces the Earth is always is changing. There are eight different Moons phases. Every month, the moon will cycle through all eight types.

3.04 Phases of the Moon

3.05 Eclipses Types of Eclipse A lunar eclipse is when the Earth blocks the Sun’s light from shining on the Moon. This blockage casts a shadow on the Moon. Lunar eclipses usually make the Moon an orange color as seen in this picture. A lunar eclipse will cast a shadow that totally covers the whole Moon because the earth is bigger than the Moon.

3.05 Eclipses A solar eclipse is when the Moon blocks the Sun’s light from shining on the Earth. This casts a shadow on the Earth. A solar eclipse will cast a shadow that only covers a portion of the Earth because the Moon is smaller than the Earth.

3.05 Eclipses What Causes an Eclipse? Lunar and solar eclipses are caused by the motion and positions of the Moon, Earth and Sun.

3.05 Eclipses

3.06 Tides It's all about gravity! Let’s look at some interesting facts about gravity. Gravity keeps us from floating into outer space. Gravity keeps the Earth on its orbit around the Sun. Gravity helps to drive the fusion reactions that give the Sun its energy. Gravity is what makes a black hole black. Finally, gravity also helps to create the tides! In this case, it is the gravity of the Moon and the Sun that cause the tides.

3.06 Tides As the Moon revolves around the Earth, the Moon’s gravity pulls on the Earth. The parts of the Earth that are most affected by this pull are the oceans and large lakes. The Moon’s pull causes the water in the oceans and large lakes to move towards the Moon.

3.06 Tides The Sun also has an effect on tides, but not as much as the Moon. Since the Moon is a lot closer to the Earth, the moon affects the tides about twice as much as the sun. When the Sun and the Moon line up, their effects work together and cause extreme high and low tides. When the Sun and the Moon do not line up the high tide and low tides are not as extreme.

3.06 Tides The Bay of Fundy in Canada has tides that are so extreme that the difference between high tide and low tide is 53 feet! That is a big tide! If you would like to see pictures of this phenomenon, go back to the introduction tab. High tide and low tide happen one hour later each day. This happens because the moon moves east in its orbit each day making the moon rise an hour later each day. Since the moon’s pull creates our tides, this delay causes our tides to happen an hour later each day.

3.06 Tides Types of Tides There are two types of tides. Spring Tide – A spring tide is when the effects of the Sun and Moon work together to bring extreme tides. A spring tide happens during a full and new moon. Neap Tide – A neap tide is when the effects of the Sun and Moon partially cancel each other out. This happens during a first quarter and third quarter moon.

3.06 Tides

3.07 Space Exploration The Beginning of Space Exploration On October 4, 1957, the Sputnik satellite was successfully launched into Earth's orbit by the Soviet Union. This event shocked the world and gave the Soviet Union the distinction of putting the first human-made object into space. This first step for the Soviets put the United States a step behind in the space race.

3.07 Space Exploration Then, a few months before the fourth anniversary of Sputnik's launch, on May 25, 1961, President John F. Kennedy made a speech to Congress that announced his plan to send an American to the Moon. He wanted to send a man to the Moon so that he would beat the Soviet Union in the space race. Because of strong political reasons, it was very important that the United States beat the Soviet Union to the Moon.

3.07 Space Exploration This was the official beginning of the United States space exploration. On that day, President Kennedy had no idea how important the space race would be to the United States. Because of space exploration we have: invented new technology helped our economy changed our culture These were unexpected outcomes due to the space race; we could say that they were a pleasant surprise.

3.07 Space Exploration Inventions Because of Space Exploration Thousands of inventions were created for space exploration. Many of these inventions were adapted for use in our everyday lives.

3.07 Space Exploration Satellite Dish NASA developed a way to communicate with spacecrafts. Because of this we now have satellite TV. Cordless Screwdriver Cordless tools were first developed to help astronauts drill for soil samples on the moon. This same technology helped us develop the cordless power tools that we use today. Smile NASA's attempts to develop a new material for spacecrafts produced a hard, see through material. This material is now used in invisible braces. You can thank space exploration for your straight smile! Firefighters The flame retardant clothing that fire fighters wear were developed for space suits. Video Game Controller Joysticks were invented to control the Apollo Lunar Rover. These are the ancestors of the controllers that you use for your computer and video games today.

3.07 Space Exploration Space Exploration has Changed our Culture and Economy Have you ever used Velcro? If it were not for space exploration, you might not have. Velcro was used by the astronauts to help them get out of the bulky space suits. Today the Velcro industry makes over $100 million. Many other industries are the result of space exploration.

3.07 Space Exploration Cell Phone Industry I bet you don’t know too many people who do not have a cell phone. The cell phone has greatly changed our culture; how people do work and how people communicate. Portable communication has its roots grounded in space exploration. Airline Industry Today, travel around the world is relatively easy. Much of the technology that airplanes use was developed as a result of space exploration. Medical Industry Much of the technology that is used today to help diagnose patients was first developed for space exploration. Tourist industry Many places around the world have museums and parks about space. Millions of people visit these destinations every year. These parks and museums bring in large amounts of money for the surrounding areas.

3.07 Advanced How We Explore Space Space travel is the best way to explore space. The reason for this is space travel allows us to gather samples and see the objects up close. Space travel does have its limitations. Time – it would take too long to send a person to the far places in our solar system or the universe. Energy source – because of our energy source, we travel way too slowly to make it that far into space. We would have to travel faster than light to go to some places in the universe. Supplies – a trip far into space would require so many supplies they would not fit on the space shuttle. We do not have the ability to send people much farther than the moon. Because of this, we have developed technology to help us reach far into space.

3.07 Advanced How We Explore Space Optical telescopes magnify and focus visible light. Any object that lets off light can be seen through an optical telescope. These telescopes make objects seem bigger and closer than they are. Optical telescopes can use lenses, mirrors, or a combination of both. The Hubble Telescope is a famous optical telescope. The Hubble was put into orbit outside the Earth’s atmosphere. This reduces the interference the telescope receives and it can see farther into space.

3.07 Advanced How We Explore Space Radio telescopes are telescopes that pick up on microwaves and radio waves that are emitted by objects in space. These telescopes are used when visible light is not present or blocked.

3.07 Advanced How We Explore Space X-ray telescope are a type of telescope that can see x-rays. X-ray telescopes are usually telescopes that are put into orbit to reduce the interference of the atmosphere. Remember that stars and many other space object emit x-rays. These telescopes help us to see aspects of objects that we could not see with visible light. X-ray telescopes are the primary tool that scientists use to study black holes.

3.07 Advanced How We Explore Space Mathematics Many times, it is impossible to observe a part of the Universe. When this is the case, scientists use math to help. In 1846, Neptune was discovered. The interesting thing about Neptune was that it was discovered without ever having been seen! Neptune was proven by math to exist. After, the math proved that Neptune existed, scientists know where in the sky to look for it and was later seen through a telescope. Albert Einstein also used math to help come up with his general formula E=mc2. This theory of relativity has since been used to help prove the existence of black holes. In fact, much of what we know about black holes has been proven by math. Math is also used to help us determine the size of objects in space and how far away these objects are. Listening to Space Many people spend time listening to space. Some feel that there may be life in outer space and that that life form is most likely to attempt to communicate with sound. This practice is showcased in many Hollywood films.

3.07 Advanced How We Explore Space Review Telescopes focus light so we can see objects off in space. Mathematics can be used to prove theories about space. People listen to space in the hope that aliens are trying to communicate with us. Mathematics can be used to prove black holes exist. Telescopes are used to see radio waves and microwaves emitted by space objects. Space travel is used to study the moon. Telescopes are used to see x-rays emitted by space objects.