Objectives Describe characteristics of the universe in terms of time, distance, and organization Identify the visible and nonvisible parts of the electromagnetic spectrum

The Value of Astronomy astronomy - the scientific study of the universe astronomers - Scientists who study the universe In the process of observing the universe, astronomers have made exciting discoveries, such as new planets, stars, black holes, and nebulas. By studying these objects, astronomers have been able to learn more about the origin of Earth and the processes involved in the formation of our solar system.

The Value of Astronomy, continued Studies of how stars shine may one day lead to improved or new energy sources on Earth. Astronomers may also learn how to protect us from potential catastrophes, such as collisions between asteroids and Earth. Astronomical research is supported by federal agencies, such as the National Science Foundation and NASA. Private foundations and industry also fund research in astronomy

Formation of the Universe The Universe began about 14 billion years ago Our solar system was formed out of a ball of spinning gas approximately 4.5 billion years ago. When the sun became luminous (bright) enough the remaining dust and gas were blown away into space, leaving the planets orbiting our sun.

Organization of the Universe Solar system - The nearest part of the universe to Earth and includes the sun, Earth, the other planets, and many smaller objects such as asteroids and comets. The solar system is part of a galaxy. Galaxy - a collection of stars, dust, and gas bound together by gravity Our solar system resides in the Milky Way galaxy. There are billions of other galaxies (1,000,000,000 +)

The arrow points to our Star, the Sun, which is only one of several hundred billion stars in the Milky Way Galaxy

Your Address on Earth 1. person 2. Small area 3. Larger area 4. Even larger area

What is your Galactic Address? Room # Alvarado Intermediate School 1901 S. Desire Street Rowland Heights California United States of America Planet Earth (third planet from the Sun) Solar System Milky Way Galaxy The Universe

Measuring Distances in the Universe The universe is so large that astronomers also use different methods to measure distance in space. astronomical unit - the average distance between the Earth and the sun; approximately 150 million kilometers (symbol, AU) Speed of Light -Light travels at 300,000 km/s. In one year, light travels 9.4607 x 1012 km. This distance is known as a light-year (symbol, LY). [9,461,000,000,000 km] A light year is a measurement of distance…not time

The Milky Way Galaxy The Milky Way is shaped like a large disk. Our Solar system lies near the outer edge of the the disk, which contains the majority of the stars, including the sun, and virtually all of the gas and dust The galaxy spans 100,000 Light- Years (LY)

Aside from the sun, the closest star to Earth is 4 Aside from the sun, the closest star to Earth is 4.2 light-years (LY) away. Remember there are hundreds of billions of stars just in our Milky Way galaxy. Out of the billions of other Galaxies the nearest one is (Andromeda) which is 2 million LY from the Milky Way.

Observing Space electromagnetic spectrum - all of the frequencies or wavelengths of electromagnetic radiation. Light, radio waves, and X rays are all examples of electromagnetic radiation. All light travels at the same speed, but different colors of light have different wavelengths. These colors can be seen when visible light is passed through a spectrum or a prism.

The human eye can see only radiation of wavelengths in the visible light range of the spectrum. These are always the same color and always in the same order . The colors of a rainbow. (violet, blue, green, yellow, orange, and red)

Invisible Electromagnetic Radiation Invisible wavelengths cannot be seen by the human eye. They include infrared waves, microwaves, radio waves, ultraviolet rays, X rays, and gamma rays, and are detected only by instruments. In 1852, a scientist named Sir Frederick William Herschel discovered infrared, which means “below the red.” Infrared is electromagnetic radiation that has waves longer than waves of visible light. Ultraviolet means “beyond the violet” and has wavelengths shorter than waves of visible light.

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