unit 2 lesson 1 what objects are part of the solar...

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.


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.


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.


The Solar System


• Earth rotates once on its axis every 24 hours.

• That is the length of one day on Earth.


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.


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.


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.

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.



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.



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.



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.




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.

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.



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.



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.



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.




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.


The Flying Objects


• Moons in our solar system differ from each other.

• Some moons may contain a lot of ice.

• Some moons have many volcanoes.

Moons

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.



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.



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.



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.




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.

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