# Describing the universe.

## What is astronomy

Astronomy is the scientific study of the universe. Scientists that study astronomy are called astronomers. Astronomy has a lot of value because they discover new things planets and stars. Astronomers have been able to know more about the origin of the earth and the processes involved in the formation of the solar system. With astronomy we know if an asteroid is going to hit us and we can make a new type of energy when we study the stars.

## Objective

1.Describe characteristics of the universe in term of time, distance and organization.

2.Identify the visible and non visible parts of the electromagnetic spectrum.

3.Compare refracting telescopes and reflecting telescopes.

4.Explain how telescopes for no visible electromagnetic radiation differ from the light telescopes.

## Electromagnetic spectrum

An Electromagnetic Spectrum is all of the frequencies or wavelengths of electromagnetic radiation. Light, radio waves, and x rays are examples of electromagnetic radiation. The radiation is composed of traveling waves of electric and magnetic fields that oscillate at fixed frequencies and wavelengths.

Visible light if formed by energy that is part of the electromagnetic spectrum. The shortest wavelengths of visible light are blue and violet. All light travels at the same speed different colors of light have different wavelengths. The human eye can see only

## Comparing the Reflecting and refractories telescope

The Reflecting Telescope was invented my Issac Newton. When light enters a reflecting telescope the light is reflected by a large curved mirror to a second mirror. The Reflecting telescope is much more bigger and gathers more light. The Refactoring telescope has lenses the lenses are clear objects shaped to bend light in special ways. The Refactoring telescope use a set of lenses to gather and focus light from distant objects. One problem with the refactoring telescope is that the lenses focus different colors, this lense are very difficult to make because they are very big. Both of these telescopes are called optical telescopes they both gather and focus light and collect EM radiation in the sky.

## Invisible Light Telescope

Invisible light telescope provide different information about objects in space. Scientists have developed telescopes that detect invisible radiation. This telescope can detect gamma rays, x rays and infrared rays. One problem with using the telescope is to detect visibleEM radiation is that the earths atmosphere acts as a shield against many EM radiation. This telescope works better in high elevations and where the air is dry.

## Space Based telescope

Valuable information has come from spacecraft. Space craft that contains telescopes and other instruments have been launched to investigate planets stars and other distant objects. In space earths atmosphere can not interfere with detection of EM radiation. The Hubble Space telescope is an example of a telescope that has been launched into space to collect EM radiation from objects in space