# Describing the universe

## What is Astronomy?

Astronomy is the scientific study of the universe. Which the value of astronomy is really important to humans was that farmers would predict floods and droughts by checking the year and track the seasons. Today, now in the future they try to discover new things in the astronomic life whether than the Earth. We should check like a meteorite is coming up to Earth (like the Russia meteor), solar eclipse and comets.

## Objectives

1. Identify the visible and nonvisible parts of the electromagnetic spectrum.

2. Compare refracting telescopes and reflecting telescopes.

3. Explain how telescopes for nonvisible electromagnetic radiation differ light telescopes.

## Describe the Electromagnetic Spectrum

The Electromagnetic spectrum is all of the frequencies or wavelengths of electromagnetic radiation. Both of Invisible and Visible Electromagnetic wavelengths, they all travel in the same speed and they both have a colorful wavelength.

For the Visible Electromagnetic Radiation it has visible lights is a form of energy that is part of the electromagnetic spectrum, the human eyes can only see the radiation of wavelengths and the shortest wavelengths of visible lights are blue and violet.

For the Invisible Electrogmagnetic Radiation it has the longest wavelengths of invisible lights are orange and red, these invisible wavelengths include infrared waves, microwaves, radio waves, ultraviolet rays, x-rays, and gamma rays, invisible light can't be see by the human eyes and we need a special instrument to detect electromagnetic radiation.

## Compare Refracting and Reflecting telescopes

The refracting telescope is a telescope that uses a set of lenses to gather and focus light from distant objects. On refracting their differences are that the lenses are clear objects shaped tobend in special ways, a set of lenses to gather and focus light from distant objects, have an objective lens that bends light that passes through the lens and focuses the light to magnified by an eye piece, lens focuses different colors of light at different distance, problem with refracting telescopes is that it is difficult to make very large lenses of the required strength and clarity and amount of light collected from distant objects is limited by the size of the objective lens.

The reflecting telescope is a telescope that uses a curved mirror to gather and focus light from distant objects. On reflecting their differences are that they use a curved mirror to gather and focus light is reflected from distant objects, light enters a reflecting telescope, light is reflected by a large curved mirror to a second mirror, the second mirror reflects the light to the eyepiece, lens that magnifies and focuses the image and mirrors in reflecting telescopes can be made very large without affecting the quality of the image.

## Invisible Light Telescopes

The invisible light telescope detects radio waves, also detect gamma rays, x-rays and infrared rays. One problem with using telescopes to detect invisible telescopes to detect invisible electromagnetic radiation. Is that Earths's atmosphere acts as a shield against many forms of electromagnetic radiation, water vapor can prevent gamma rays, x-rays, and most infrared and ultra violet rays reaching Earth's surface. So, ground-based telescopes that are used to study these forms of radiation work best at evaluation, where they are dry. But, the only ways to study many forms of radiation is from space.

## Space Base Telescopes

The space base telescope have the Hubble Space, is an example of a telescope that has been launched into space to collect all electromagnetic radiation from other objects in space. Another example, the Chandra x-ray observatory makes remarkably clear images using -rays from objects in space, such as the remnants of exploded stars. The Compton Gamma Ray observatory is no longer in space, but it detect black holes. The Spitzer space was launched in 2003 to detect infrared radiation. The James Webbspace telescope is to detect infrared radiation objects in space.