Unit 2 Lesson 1 What Objects Are Part of the Solar System? Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 2 Lesson 1 What Objects Are Part of the Solar System? Florida Benchmarks SC.5.E.5.2 Recognize the major common characteristics of all planets and compare/contrast the properties of inner and outer planets. SC.5.E.5.3 Distinguish among the following objects of the Solar System—Sun, planets, moon, asteroids, comets—and identify Earth’s position in it. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 2 Lesson 1 What Objects Are Part of the Solar System? Earth, other planets, and moons are part of a solar system. Solar systems are made up of a star and the planets and other space objects that revolve around it. Planets are large, round bodies that revolve around a star. Copyright © Houghton Mifflin Harcourt Publishing Company

The Solar System There are eight planets in our solar system. Unit 2 Lesson 1 What Objects Are Part of the Solar System? The Solar System There are eight planets in our solar system. All planets rotate, or spin, around an axis. An axis is an imaginary line that goes through the center of the planet. Copyright © Houghton Mifflin Harcourt Publishing Company

The Solar System Earth rotates once on its axis every 24 hours. Unit 2 Lesson 1 What Objects Are Part of the Solar System? The Solar System Earth rotates once on its axis every 24 hours. That is the length of one day on Earth. Copyright © Houghton Mifflin Harcourt Publishing Company 5

The Solar System In our solar system, the planets orbit the sun. Unit 2 Lesson 1 What Objects Are Part of the Solar System? The Solar System In our solar system, the planets orbit the sun. The orbits are oval-shaped, or elliptical. The planets in our solar system are very far from one another. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 2 Lesson 1 What Objects Are Part of the Solar System? Moons are small, natural objects that revolve around other objects. Earth has one moon that revolves around Earth about every 27 days. Some planets have more than one moon. Mercury and Venus do not have any moons. Copyright © Houghton Mifflin Harcourt Publishing Company 7

Unit 2 Lesson 1 What Objects Are Part of the Solar System? The Inner Planets The four inner planets are Mercury, Venus, Earth, and Mars. The inner planets are very dense and rocky. They also have thin atmospheres and small diameters. The inner planets have large solid cores and few moons. Copyright © Houghton Mifflin Harcourt Publishing Company

Mercury Mercury is the smallest planet in our solar system. Unit 2 Lesson 1 What Objects Are Part of the Solar System? Mercury Mercury is the smallest planet in our solar system. The surface of Mercury is full of craters. Mercury is the closest planet to the sun. Copyright © Houghton Mifflin Harcourt Publishing Company

Venus Temperatures on Venus are high enough to melt lead. Unit 2 Lesson 1 What Objects Are Part of the Solar System? Venus Temperatures on Venus are high enough to melt lead. Thick clouds on Venus are made up mostly of carbon dioxide. There are more than 1,000 volcanoes on Venus’s surface. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 2 Lesson 1 What Objects Are Part of the Solar System? Earth Earth has an atmosphere made of mostly nitrogen, oxygen, and carbon dioxide. Earth is the only planet known to have abundant liquid water. Water helps keep Earth at temperatures that allow life. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 2 Lesson 1 What Objects Are Part of the Solar System? Mars Mars is known as the “Red Planet” because of its red, rocky surface. Giant dust storms cover the entire planet. There are also huge volcanoes on Mars. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 2 Lesson 1 What Objects Are Part of the Solar System? The Outer Planets The planets farthest from the sun are Jupiter, Saturn, Uranus, and Neptune. The outer planets are known as gas giants. They are huge and made up mostly of gases. All of the outer planets have many moons and ring systems. Copyright © Houghton Mifflin Harcourt Publishing Company

Jupiter Jupiter is the largest planet in the solar system. Unit 2 Lesson 1 What Objects Are Part of the Solar System? Jupiter Jupiter is the largest planet in the solar system. Massive, spinning storms, such as the Great Red Spot, are visible on Jupiter. Jupiter has rings, but they are faint. Copyright © Houghton Mifflin Harcourt Publishing Company

Saturn Saturn is the second-largest planet in the solar system. Unit 2 Lesson 1 What Objects Are Part of the Solar System? Saturn Saturn is the second-largest planet in the solar system. Saturn has thousands of rings around it. The rings are made of ice and chunks of rock. Saturn has many moons and large storms, like Jupiter. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 2 Lesson 1 What Objects Are Part of the Solar System? Uranus The axis of Uranus is tilted so far that it appears to rotate on its side. Heated gases deep inside Uranus bubble and burst onto the surface, causing bright clouds to form. Uranus has at least 13 faint rings. Copyright © Houghton Mifflin Harcourt Publishing Company

Neptune Winds on Neptune can reach 2,000 km/hr. Unit 2 Lesson 1 What Objects Are Part of the Solar System? Neptune Winds on Neptune can reach 2,000 km/hr. The Great Dark Spot on Neptune is a storm that travels around the planet. Neptune has nine rings around it. Copyright © Houghton Mifflin Harcourt Publishing Company

Compare Inner and Outer Planets Unit 2 Lesson 1 What Objects Are Part of the Solar System? Compare Inner and Outer Planets Size, surface features, distance from the sun, temperatures, number of moons, and diameter make the inner and outer planets different. The period of revolution of a planet is the time it takes for a planet to revolve around the sun. The period of rotation of a planet is the time it takes to rotate on its axis. Copyright © Houghton Mifflin Harcourt Publishing Company

The Flying Objects Moons Unit 2 Lesson 1 What Objects Are Part of the Solar System? The Flying Objects Moons Moons in our solar system differ from each other. Some moons may contain a lot of ice. Some moons have many volcanoes. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 2 Lesson 1 What Objects Are Part of the Solar System? Dwarf Planets Pluto was once classified as a planet. Now it is classified as a dwarf planet. Dwarf planets are nearly round bodies whose orbits cross the orbits of other bodies. Dwarf planets are very far away and hard to study. Copyright © Houghton Mifflin Harcourt Publishing Company

Asteroids Asteroids are rock and iron objects that orbit the sun. Unit 2 Lesson 1 What Objects Are Part of the Solar System? Asteroids Asteroids are rock and iron objects that orbit the sun. Millions of asteroids are found in the wide region between Mars and Jupiter known as the asteroid belt. Asteroids range in size from as small as a city block to the size of an ocean. Copyright © Houghton Mifflin Harcourt Publishing Company 21

Meteoroids, Meteors, and Meteorites Unit 2 Lesson 1 What Objects Are Part of the Solar System? Meteoroids, Meteors, and Meteorites Meteoroids are pieces of rock that break off asteroids and travel through space. Meteor is a term used to describe the streak of light caused when a meteoroid burns up in Earth’s atmosphere. If a meteoroid reaches Earth’s surface, it is called a meteorite. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 2 Lesson 1 What Objects Are Part of the Solar System? Comets A chunk of frozen gases, rock, ice, and dust is known as a comet. As comets pass close to the sun, part of the frozen surface breaks away and turns into gases and dust. These particles reflect sunlight and look like long tails that always point away from the sun. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 2 Lesson 1 What Objects Are Part of the Solar System? Space Watch Objects such as comets, meteoroids, and asteroids can hit the surface of other bodies in the solar system. The impact, or hit, from space objects creates impact craters. Scientists keep track of the size, position, and motion of space objects near Earth using telescopes. Copyright © Houghton Mifflin Harcourt Publishing Company