STUDY GUIDE: Earth Sun Moon

Transcription

1 The Universe is thought to consist of trillions of galaxies. Our galaxy, the Milky Way, has billions of stars. One of those stars is our Sun. Our solar system consists of the Sun at the center, and all of the objects that move around it. Eight planets, their Moons, and asteroids all make up our solar system. Inner planets Outer planets Asteroid belt Our solar system has one Sun and 8 planets. Pluto is considered a dwarf planet. Some of the planets have moons and some do not. In this illustration, the size of planets and distance from each other are NOT TO SCALE. Asteroid belt Planet: Large round body that orbits the sun. The Earth is the only planet with the conditions for life in our solar system. An Orbit is the path around another objet in space. Planets orbit suns, Moons orbit planets. Moon: A natural object that orbits a planet. The SUN is the largest object in the solar system. It provides the Earth with light and heat. It is the source of all energy on Earth. The Sun is a medium size star made of the gases Hydrogen and Helium. A satellite is a natural or artificial body in orbit. The Moon is a satellite of the Earth.

2 Facts about the SUN The sun is the source of all light, energy and heat in our solar system. Without it, our planet probably wouldn't be here, and we certainly wouldn't. What is the Sun? The sun is a star--similar to many of the stars we see in the night sky. Compared to other stars we know about, the sun is a medium-sized star. The sun is made of gas, mostly hydrogen and helium. These elements spin around violently at the sun's center, creating the light and energy we depend on for everyday life here on Earth. How Big is the Sun? The sun is the largest object in our solar system. Though it may look small from our perspective, the sun is actually big enough to fit 1 million earths inside of it. The sun appears so small to us because we're so far away from it--it's roughly 93 million miles away from our planet. We're so far away, in fact, that it even takes light eight minutes to reach us from the sun. The Sun is the center of our solar system. All of the planets and their Moons orbit the Sun. It takes the Earth 365 days, or 1 year, to orbit the Sun once. How Old is the Sun? The sun, like other stars, was formed from a nebula. Nebulas are huge swirling clouds of gas that contain all of the matter needed to create a star. Eventually, the nebula began closing in on itself, beginning the sun's creation process. The sun is about four and a half billion years old. It is expected to have a total lifespan of 10 to 11 billion years, so it's almost in the middle of its life cycle. When the sun is ready to die, it will grow large enough to engulf the nearest planets before condensing into a white dwarf star. Does the Sun Orbit? All of the planets in our solar system orbit around the sun. Similarly, the sun and all of its planets orbit around the center of the Milky Way galaxy we belong to. The galaxy is so big, however, that it takes the sun a whopping 225 million years to complete one full orbit. How Hot is the Sun's Surface? The sun's surface is about 10,000 degrees Fahrenheit, with the core reaching a scorching 28 million degrees.

3 Layers of the Sun Core: The center of the Sun. It is 28 million degrees at the core and creates all of the light and heat we use on our planet. Radiation zone: moves heat from the core to the outer layer. It is 7 million degrees in this zone. Convection zone: area where heat is moved to the Sun s surface. Photosphere: The outermost layer of the Sun. When we look at the Sun through a telescope, the light we see is the photosphere. It is 10,000 degrees F on the photosphere. area. Sunspots: Areas on the photosphere where it is cooler than the surrounding Solar flares: Explosions on the Sun s surface that emit bursts of solar energy. Prominence: Huge arches of gas that billow out from the Sun s surface. The layers of the Sun s atmosphere are the chromospheres and corona, which are only visible during an eclipse.

4 The Moon is about ¼ the size of Earth. Like the Earth, the Moon consists of three layers (core, mantle, crust). It also has similar landforms, such as mountains, plains, old lava flows (Maria), and craters. The Moon is different from the Earth in many important ways: The Moon is made up only of rock. There is no liquid water, although scientists have recently found evidence of frozen water buried in the dust. The Moon has no atmosphere. Without an atmosphere, there is no oxygen to breathe, and the temperatures are much more extreme. It is much hotter during the day (107 C), and much colder at night (-153 C). Without an atmosphere, there is no life on the Moon. The Moon has less mass than the Earth, and so there is less gravitational pull. A person s WEIGHT is less on the Moon than the Earth. A person s MASS is the same on the Earth as it is on the Moon. The Moon is about 240,000 miles (285,000 km) from Earth The Moon orbits the Earth once every 27 days. The same side of the Moon always faces the Earth. Due to the angle of the Sun on the Moon, we see different portions of the Moon each night called phases. The Moon causes TIDES on the Earth. The force of gravity from the Moon reaches the Earth and pulls the oceans toward the Moon, causing tides. Gravity from the Sun also affects tides. The highest tides occur when the Moon and Sun are aligned (during a New Moon or Full Moon). The Surface of the Moon: The Moon shines at night due to the reflection of the Sun. The Moon does not make its own light. Maria (dark spots) are caused by ancient lava flows. Craters are caused by meteor impacts over millions of years. You can see the craters on the Moon s surface.

5 The Earth The Earth is the third planet from the Sun. The Earth has three layers- core, mantle, and crust. The layers of the Earth are made up of various materials- some is rocky, and some is liquid or partially melted. The Earth has an atmosphere, made up primarily of the gases Nitrogen (78%), Oxygen (21%), and traces of other gases such as Carbon Dioxide. The atmosphere is also made up of layers. The bottom layer (troposphere) is where all living things are, and where our weather occurs. Without our atmosphere, there would be no water, and no life. Life exists on Earth for three BIG reasons: 1. We are the perfect distance from the Sun (not too hot, not too cold!) 2. We have water 3. We have oxygen The Earth spins on an axis every 24 hours. The axis is on a tilt. The line that goes around the middle is called the Equator. The halves of the Earth are split into hemispheres: the Northern Hemisphere and Southern Hemisphere. We live in the Northern Hemisphere. In the summer, the Northern Hemisphere is tilted toward the sun, so it is warmer here.

6 The Moon moves around the Earth once every 27 days. Because of this, we see different phases of the Moon throughout the month. The Earth orbits the Sun once ever 365 days (1 year). Because of this, we have SEASONS. Seasons are due to the TILT of the Earth toward the Sun. In summer, the Northern hemisphere is tilted toward the Sun. In the winter, the Northern hemisphere is tilted away from the Sun. The Earth rotates on its axis once every 24 hours (day). Because of this, we have the DAY / NIGHT cycle. Notice that it is day when that side of the Earth is facing the Sun. It is night when that side of the Earth is away from the Sun. The line between day / night is called twilight. Because of the Earth s rotation, it makes it appear as if the Sun and stars move across the sky.