SC.8.E.5.1/SC.8.E.5.2/SC.8.E.5.3 Distinguish the hierarchical relationships between planets and other astronomical bodies relative to solar system, galaxy, and universe, including distance, size, and composition. RELATIONSHIPS BETWEEN ASTRONOMICAL BODIES

The universe is an unimaginable stretch of matter and energy and is said to be expanding rapidly It contains vast amounts of gas and dust, along with many astronomical bodies including, but not limited to planets, dwarf planets, stars, moons, asteroids, nebulae, comets, solar systems, and galaxies, all organized in a well-defined hierarchy.

Any of the eight large heavenly bodies revolving about the sun A spherical celestial body revolving about the sun, similar to a planet but not large enough to gravitationally clear its orbital region of most or all other celestial bodies Any of the heavenly bodies, except the moon, appearing as fixed luminous points in the sky at night The earth's natural satellite, orbiting the earth at a mean distance of 238,857 miles Have students attempt to define each term. Small celestial bodies made up of rocks and medals that move around between Mars and Jupiter

A cloud of interstellar gas and dust. A small celestial body made up of ice that releases dust and gas The sun together with all the planets and other bodies that revolve around it. Continue to allow students to define the terms. A large system of stars held together by the gravitational pull of the sun. The system is isolated from similar systems by vast regions of space

Galaxies shaped like an ellipse, made up of gas, dust, and mostly old stars. The universe holds billions of galaxies. A galaxy consists of gas, dust, stars, and any objects orbiting the stars. Galaxies can range from just a few million stars to over several billion stars. Galaxies are divided into three basic types based on their shape. A spiral galaxy is a disked-shaped galaxy made of a lot of gas, dust, and newly forming stars. Spiral galaxies are the brightest of the three galaxies. An elliptical galaxy is shaped like an ellipse. Elliptical galaxies have very little gas and dust and are made up of mostly old stars. Irregular galaxies do not have regular shapes. They are full of gas and dust and are also bright due to the formation of new stars. A disked-shaped galaxy made of a lot of gas, dust, and newly forming stars Do not have regular shapes. They are full of gas and dust and are also bright due to the formation of new stars.

150,000 LIGHT YEARS The Earth and the sun belong to a spiral galaxy made up of over 100 billion other stars that range in size and age called (CLICK) the Milky Way Galaxy, which holds our 4-billion-year-old solar system. It is about 150,000 light years across and is separated from other neighboring galaxies by millions of light years. (CLICK)

The gravitational pull of the sun keeps the planets on their orbit Our solar system is always in motion and is composed of the sun, the eight planets orbiting the sun, satellites (moons) of the planets, numerous asteroids, comets, and interplanetary medium. The sun is at the center of the solar system and its gravitational pull keeps the celestial bodies orbiting around it. Without the sun, the planets would fly out into space. The gravitational pull of the sun keeps the planets on their orbit

A planet is defined as is a spherical-shaped mass of rock and/or gas that revolves around a star. The eight planets in our solar system differ in size, characteristics, composition, and distance from the sun. All the planets in our solar system orbit the sun in a particular order. Closest to the sun is Mercury, then Venus, Earth and Mars, then Jupiter, Saturn, Uranus, Neptune, and finally, the dwarf planet Pluto. Have students identify each planet and discuss characteristics related of the various planets. Have students compare and contrast the planets.

The asteroid belt separates the inner planets from the outer planets. The four inner planets, known as the Terrestrial planets are Mercury, Venus, Earth, and Mars. Inner planets are typically small, rocky globes with dense atmospheres, iron cores, and few moons. The asteroid belt separates the inner planets from the outer planets. Rocks known as asteroids can be found in this belt orbiting around the Sun just as the planets do. The asteroid belt falls between Mars and Jupiter. The asteroid belt separates the inner planets from the outer planets.

The outer planets known as Jovian Planets are composed of gaseous or liquid fluids, multiple moons, ring systems, and are very cold due to their distance from the Sun. The first of these planets begin with Jupiter, followed by Saturn, Uranus and Neptune. Pluto, once known as the ninth and smallest planet in our solar system, has been downgraded to a dwarf planet.

Asteroids and comets are small celestial bodies that revolve around the sun. The main difference between an asteroid and a comet is that asteroids are made up of rocks and metals while comets are made up of ice, dust, and small rocks. Asteroids are found mostly in the Asteroid Belt between whereas ice-filled comets are formed farther from the Sun. When comets come into close proximity with the Sun, they lose mass as the ice melts and vaporize to form a tail.

Stars are far away suns that look like points of light Stars are far away suns that look like points of light. All stars emit light energy as a result of a process called hydrogen fusion. The hydrogen in the star acts as a giant ball of hot gas, fueling the star to shine. The hydrogen gas eventually runs out and the star begins to die. However, a star running out of hydrogen gas takes billions of years to occur.

Stars vary in color dependent upon their temperature Stars vary in color dependent upon their temperature. Those cooler than the sun appear red or orange. Meanwhile, the ones that look white or bluish-white in color are hotter than the sun. As stars get older they change in size and temperature.

EQUALS TO 5.9 TRILLION MILES ASTRONOMICAL UNIT 93 MILLION MILES Because the universe is so vast, distances between objects in space is measured in light years. What is a LIGHT YEAR? A light year defines the distance that light travels in one year, which equates to nearly 5.9 trillion miles. In our solar system, we can describe distance in a smaller unit of measurement called the (AU) or astronomical unit. The AU is the average distance between the Earth and the Sun, which is about 93 million miles.

RELATIONSHIPS BETWEEN ASTRONOMICAL BODIES