Space Science Astronomy Chapter 26

What is Astronomy Chapter 26-1 Astronomy- Study of the stars, planets and other objects in space. *Astronomy is one of the oldest sciences. Dates back to 2,000 B.C. century. *Astronomers discovered the planets nearer the sun 5,000 years ago. * Early civilizations relied on the science of astronomy for many things. Modern Astronomy- Uses tools that can enhance the distances astronomers can observe. * Modern astronomers study the universe. The universe is everything that exist * Planetologist- Astronomers that study the solar system. Solar System- Includes the Sun and all the bodies in space that orbit it. Cosmologist- Astronomers that study how the Universe began and how it will end. Historical Astronomers *Aristotle- Claimed that the Earth was at the center of the universe. (Geocentric Theory) *Copernicus- Suggested that the Sun was at the center of the Solar system. (Heliocentric Theory) * Brahe, Kepler, Galileo, Newton supported Copernicus. Beginning of modern Astronomy.

Space Exploration Chapter 26-2 Galaxy- huge collection of stars, gas and dust that travels through space. *Space age began in 1957, with the Russian space craft Sputnik. *Goal of space exploration is to answer questions about the Universe. How the Universe Formed- About 15 billion years ago a huge explosion called the Big Bang, was believed to have created distant galaxies. *Hubble Telescope- Spaced based telescope that orbits the Earth. Launched in 1990.

Refracting Telescope Chapter 26-3 Refracting Telescope- telescope that uses convex lenses to produce enlarged images. Convex Lens- lens that is thicker in the middle than it is at its edges. * Galileo was the first person to look at objects in space through a telescope. Refract- To bend light inward. * The objective lens brings the light into the telescope. * The eyepiece magnifies or enlarges the object being viewed.

Reflecting Telescope Chapter 26-4 Reflecting Telescope- telescope that uses a concave mirror to collect light. Concave Mirror- mirror that curves inward. * A reflecting telescope uses a mirror to redirect light. * Newton(1668) made the first reflecting telescope. Used a mirror to collect the light and a convex lens to magnify the image. Schmidt telescope- A reflecting telescope that uses a camera to take pictures of celestial bodies.

Radio Telescope Chapter 26-5 Radio Telescope- Non-optical telescope that can receive radio waves from sources in space. * Stars like our Sun, can only be seen when it is dark. Clouds or light from the Sun and cities can block out or obscure star light. * Stars send out visible light and all forms of electromagnetic radiation.

Radio Telescope Radio telescope uses an antenna to collect and focus radio waves to a receiver. Karl Jansky (1932) was the first person to listen to radio signals from space. Advantages to using a radio telescope; They can detect objects that reflecting and refracting telescopes cannot. Can be used in any type of weather. Can be used during the day.

Chapter 26-6 How Astronomers Measure Distances? Light Year- unit of measurement equal to about 10 trillion Km or 6 trillion miles. *Distance light travels in one year. (300,000 Km/sec. or 186,000 mi/sec) *Measuring distance in space creates very large numbers. *Light from the Sun takes about 8 minutes to reach the Earth. Light from the North Star –Polaris takes about 700 years to reach the earth. Parallax- apparent change in the position of a distant object when seen from two different positions. *Astronomers use parallax to find the distances to stars.

Measuring Distance Astronomical Unit- unit of measurement based on the Sun’s distance from Earth and equal to about 150 million Km. * Varies based on the Earth’s position in its orbit. (1 AU= 150,000,000 Km). Used to measure planetary distances. Parsec- Distance equal to 3.26 LY.