Viewing the universe

Descriptive vocabulary

What is astronomy?

Astronomy is the scientific study of the universe. In the process of observing the universe, astronomers have made exciting discoveries, such as new planets, stars, and black holes. Studying the universe gives humans potential benefits. One example, is how the stars shine, will one day give earth new energy sources.


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

Compare refracting telescopes and reflecting telescopes.

Explain how telescopes for non visible electromagnetic radiation differ from light telescopes.

Astronomy vocabulary

Describe the electromagnetic spectrum

The electromagnetic spectrum is all of the frequencies or wavelengths of electromagnetic radiation. There are two types of electromagnetic radiation, and they are visible radiation, and invisible radiation. The visible radiation is visible light. Visible light is a form of energy. The human eye can only see visible light. Invisible radiation includes infrared waves, microwaves, radio waves, x rays, and gamma rays. Invisible radiation can only be detected by a special instrument. Visible radiation, and invisible radiation both come from stars. They are both part of the EM spectrum. They both travel in wavelengths. Both radiations travel at the same speed which is 300,000 kilometers per second.

Compare the refracting and reflecting telescopes

Both the refracting and reflecting telescopes are optical, meaning they can both analyze visible light. The refracting telescope uses clear, objective lenses to gather and focus light from distant objects. One problem with refracting telescopes is that the lens focuses different distances. For example, if an object is in focus in red light, the object will appear out of focus in blue light. Another problem with refracting telescopes is that it is difficult to make very large lenses of the required strength and clarity. The reflecting telescope uses a curved mirror to gather and focuses light from distant objects. When light enters a reflecting telescope, the light is reflected by a large curved mirror to a second mirror. The second mirror reflects the light to the eyepiece, which is a lens that magnifies and focuses the image. Unlike objective in refracting telescopes, mirrors in reflecting telescopes can be mad very large without affecting the quality of the image.

Invisible light telescope, and space based telescope

These are both telescope that can detect infrared rays and other things. An example of an invisible light telescope is the radio telescope which decries radio waves. There also telescopes that detect gamma rays. And X-rays, and infrared rays. Water vapor can prevent gamma rays, X-rays and ultra violet rays from reaching earths's surface. The Hubble space telescope is an example of a telescope that has been launched into space to collect electromagnetic radiation from objects in space. Another example, the Chandara X-rays observatory makes remarkably clear images using X-rays from objects in space, such as the remnants of exploded stars. The Spritzer Telescope was launched in 2003 to detect infrared radiation. The James Webb space telescope is scheduled to be launched in 2014. When deployed in space, this telescope will detect infrared radiation from objects in space.