The electromagnetic spectrum describes the range of wavelengths or frequencies over which electromagnetic radiation extends. Radio waves are a type of electromagnetic radiation with wavelengths longer than infrared light that are used for radio communication. The Hubble, Spitzer, and Chandra telescopes observe different wavelengths of light from space, including visible light, infrared, and X-rays, in order to take sharp pictures of astronomical objects like planets, stars, and galaxies. Telescopes are placed in space to obtain clearer views of the universe free from atmospheric interference and to observe wavelengths like X-rays and infrared that are blocked by Earth's atmosphere. Astronomers look for water on other planets because water is currently the best known indicator for the potential existence of life, and SETI stands

1. The Electromagnetic Spectrum

2. What is the Electromagnetic Spectrum
The range of wavelengths or frequencies over which electromagnetic
radiation extends.

3. Radiowaves: how it is used?
•Radio waves are a type of electromagnetic radiation with wavelengths
in the electromagnetic spectrum longer than infrared light.

4. Hubble Telescope
Hubble takes sharp pictures of
objects in the sky such as planets,
stars and galaxies. Hubble has made
more than one million observations.
These include detailed pictures of the
birth and death of stars, galaxies
billions of light years away, and
comet pieces crashing into Jupiter's
atmosphere.

5. Spitzer Telescope
Spitzer is designed to take both images and spectra by detecting infrared, wavelengths this kind of light has
longer wavelengths than visible light, beyond 700 nm. Any warm object in space radiates IR energy (infrared
energy, which we sense as heat). In fact, "warm" really means any object above absolute zero, because any
object above absolute zero releases some wavelength of IR energy. The Spitzer Space Telescope is designed to
detect infrared energy

6. Chandra Telescope
Chandra can observe X-rays from clouds of gas
so vast that it takes light five million years to go
from one side to the other!.

7. WHY PLACE TELESCOPES IN SPACE?
Telescopes are placed into orbit around the Earth or are sent farther out into space to get a clearer view
of the Universe. There are many different types of space telescopes. Some are used to study a special
object like the Sun. Others are used to study the different types of light given off by objects in space. X-
ray and gamma-ray telescopes study the hottest and most explosive objects in space. Infrared telescopes
study the places where stars are born and can look into the centers of galaxies. Optical telescopes study
the visible light from space and ultraviolet telescopes study very hot stars. Many of these types of light
(such as x-rays, gamma-rays, most ultraviolet, and infrared) can only be studied from space because they
are blocked by our atmosphere.In space, however, telescopes are able to get a clearer shot of everything
from exploding stars to other galaxies. Another disadvantage for ground-based telescopes is that the
Earth's atmosphere absorbs much of the infrared and ultraviolet light that passes through it.

8. WHY DO ASTRONOMERS LOOK FOR
WATER ON OTHER PLANETS
So far that we have gathered scientifically, water is an indicator of life. Science can only go so fast, and
we are making new discoveries all the time.
It is for this reason that we can only currently 'assume' that life can only be found where water is
evident. We can take a look at the species on our planet, given how lush nature is, and see exactly what
an environment with a lot of water can create.
Maybe someday we'll find just as large an indicator of life with other elements (like sulfur for example)
as we do water, when we explore more of the universe.

9. WHAT DOES SETI STAND FOR?
SETI stands for Search for Extra-Terrestrial Intelligence. The acronym was coined in the early 1960's
to describe the activities of a handful of radio astronomers who were seeking evidence of the existence
of intelligent life elsewhere in the Universe