1. What is Electromagnetic radiation Infrared cosmos
All objects emit infrared radiation.
Infrared detectors detect wavelengths which are between wavelengths of about 1 and 300 microns (a micron is one millionth of a meter)
The human eye detects only 1% of light at 0.69 microns, and 0.01% at 0.75 microns, and so effectively cannot see wavelengths longer than about 0.75 microns unless the light source is extremely bright.
It is a stream of photons that
Each traveling in a wave-like pattern at right angles
Moving at the speed of light
Carrying some amount of energy.
They differ in the amount of energy of the photons.
Wavelength (m)
Frequency (Hz)
Energy (J)
Radio
> 1 x 10-1
< 3 x 109
< 2 x 10-24
Microwave
1 x x 10-1
3 x x 1011
2 x x 10-22
Infrared
7 x x 10-3
3 x x 1014
2 x x 10-19
Optical
4 x x 10-7
4 x x 1014
3 x x 10-19 UV
1 x x 10-7
7.5 x x 1016
5 x x 10-17
X-ray
1 x x 10-8
3 x x 1019
2 x x 10-14
Gamma-ray
< 1 x 10-11
> 3 x 1019
> 2 x 10-14
Absorption of Electromagnetic waves
Gamma and X-ray: Oxygen and Nitrogen
UV rays: Oxygen and Ozone
Infrared waves: Water
Ultraviolet Waves
Wave-particle duality of light:
Light behaves like a wave and particle
Trend: Low energy photons behave more like waves while higher energy photons behave more like particles.
This affects how detectors and telescopes are designed to try to 'see' EM radiation from very low to very high energies.
Effects: Sunburns and skin cancer
Detecting cool objects
Sun at extreme UV wavelength
How earth glows in UV light
Exploring the early universe
Hottest and the most active objects in the cosmos give off large amounts of ultraviolet energy.
Applications:
Discern the …
Chemical composition
Densities
Temperatures of the interstellar medium
Temperature and composition of hot young stars.
Sterilise glassware
Signature of hotter objects
E = h x nu
Where E = Energy
H= Planck’s constant = x erg-seconds
Nu = Frequency
299,792,458 m/s
X-rays and Gamma rays
Sources of Radiowaves
X rays and some gamma rays are produced throughout the universe by the same catastrophic astrophysical events, such as supernovas and black holes.
Quasars: one of a class of blue celestial objects having the appearance of stars when viewed through a telescope and currently believed to be the most distant and most luminous objects in the universe
2) Radio galaxies.
Measuring Cosmic Radiation
The infrared part of the spectrum is where the emission and absorption lines of virtually all molecules as well as numerous atoms and ions (electrically charged atoms) lie. Infrared spectroscopy is the primary way to detect these elements in space.

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