Matthew Brenden Wood - 15 Sept

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Planets

Introduction

Studying Other Planets

What is planetary science?

Planetary science is the scientific study of planets, moons, asteroids, comets, and other objects in the solar system. To study these objects, planetary scientists use many different areas of science, such as astronomy, chemistry, physics, meteorology, and geology.

If you go outside on a clear night and look up, you might be able to see one or more planets. Mercury, Venus, Mars, Jupiter, and Saturn are all visible from our own planet, Earth. What are these celestial objects? Why is it important to learn about them?

Planetary scientists work to understand what planets are made of, what characteristics they share, and how they are different. They study the history of planets and their behaviors. These scientists search for answers to questions that people have had about planets since humans first looked up in the sky.

About 4.6 billion years ago, our solar system was new. It was nothing more than a huge cloud of swirling hydrogen gas, dust, and ice particles called a molecular cloud. Created from the violent death of an ancient star called a supernova, the giant cloud stretched a few light-years across, slowly churning in space.

Gradually, the grains of dust and wisps of gas began to clump together. The clumps grew larger as their gravities pulled in more material.

In the hot, dense center of the cloud, a proto-sun formed. The rest of the cloud formed a swirling disk around it called the solar nebula. Inside the solar nebula, microscopic particles of dust and ice continued to move about, sometimes colliding and sticking together.

During the course of millions of years, this process, called accretion, formed objects a few miles across. These objects are called planetesimals, and they are the building blocks of planets. As millions more years passed, these planetesimals collided and merged with each other. Among the debris, only a few remained.

Today, our solar system consists of eight planets and their moons, dwarf planets, asteroids, and comets. Planetary science is the study of these objects, and it involves many different branches of science working together to try to answer some very big questions.

Where did these objects come from? Why are some of them so similar and others so different? Is our solar system unique?

Vocab Lab

There is a lot of new vocabulary in this book! Turn to the glossary in the back when you come to a word you dont understand. Practice your new vocabulary in the VOCAB LAB activities in each chapter.

Scientific Method

The scientific method is the process scientists use to ask questions and find answers. Keep a science journal to record your methods and observations during all the activities in this book. You can use a scientific method worksheet to keep your ideas and observations organized.

Question: What are we trying to find out? What problem are we trying to solve?

Research: What is already known about this topic?

Hypothesis: What do we think the answer will be?

Equipment: What supplies are we using?

Method: What procedure are we following?

Results: What happened and why?