CHAPTER 1CHAPTER 1Astronomy and the UniverseAstronomy and the Universe

CHAPTER 1CHAPTER 1Astronomy and the UniverseAstronomy and the Universe

What we will learn…

How exploring other planets provides insight into the origins of the solar system and the nature of our Earth

Stars have a life cycle—they form, evolve over millions or billions of years, and die

Stars are grouped into galaxies, which are found throughout the universe

How astronomers measure the positions and sizes of celestial objects

How to express very large or very small numbers in convenient notation

Why astronomers use different units to measure distances in space

What astronomy can tell us about our place in the universe

Astronomy, Science, and the Nature of the Universe

The universe is comprehensible.

The scientific method is a procedure for formulating hypotheses about the universe.

These are tested by observation or experimentation in order to build consistent models or theories that accurately describe phenomena in nature

Observations of the heavens have helped scientists discover some of the fundamental laws of physics.

The laws of physics are in turn used by astronomers to interpret their observations.

Astronomy, Science, and the Nature of the Universe

Exploration of the planets provides information about the origin and evolution of the solar system, as well as about the history and resources of Earth.

The Solar System

The Sun and Planets to ScaleThe Sun and Planets to Scale

Studying the stars and nebulae helps us learn about the origin and history of the Sun and the solar system.

Stars & Nebulae

Observations of galaxies tell us about the origin and history of the universe.

Galaxies

Astronomers use angles to denote the positions and sizes of objects in the sky.

The size of an angle is measured in degrees, arcminutes, and arcseconds.

Angular Measure

Small-Angle Formula

Note: “α” has to be in arcseconds !!!

Speed of Light “c”

c = 300 000 000 m/s

This is a convenient shorthand system for writing numbers.

It allows very large and very small numbers to be expressed in a compact form.

Powers-of-Ten Notation

Astronomers use a variety of distance units.

These include:•astronomical unit or (the average distance from Earth to the Sun)•light-year or ly (the distance that light travels in one year)•parsec or pc

Units of Distance

Key Ideas Astronomy, Science, and the Nature of the Universe: The

universe is comprehensible. The scientific method is a procedure for formulating hypotheses about the universe. These are tested by observation or experimentation in order to build consistent models or theories that accurately describe phenomena in nature.

Observations of the heavens have helped scientists discover some of the fundamental laws of physics. The laws of physics are in turn used by astronomers to interpret their observations.

The Solar System: Exploration of the planets provides information about the origin and evolution of the solar system, as well as about the history and resources of Earth.

Stars and Nebulae: Studying the stars and nebulae helps us learn about the origin and history of the Sun and the solar system.

Galaxies: Observations of galaxies tell us about the origin and history of the universe.

Angular Measure: Astronomers use angles to denote the positions and sizes of objects in the sky. The size of an angle is measured in degrees, arcminutes, and arcseconds.

Powers-of-Ten Notation is a convenient shorthand system for writing numbers. It allows very large and very small numbers to be expressed in a compact form.

Units of Distance: Astronomers use a variety of distance units. These include the astronomical unit (the average distance from Earth to the Sun), the light-year (the distance that light travels in one year), and the parsec.

Key Ideas