1. Electromagnetic spectrum part 2
The higher frequency types of electromagnetic energy are dangerous to humans
How are humans protected from the dangerous waves?
Electromagnetic spectrum part 2

2. Ultraviolet (7.5 x x 1016 Hz)
UVA and UVB rays are from the sun and too much can cause direct DNA damage like sunburns and skin cancers, even blindness
UVB rays in the right amount can encourage Vitamin D production in the skin.
The Earth’s ozone layer filters out most of the harmful UV rays.
Human eyes can’t detect Ultraviolet Light
but some insects can.

3. Some sources of UV rays would be stars and galaxies.
An ultraviolet telescope in the space shuttle.
Our sun is a star

5. X-RAYS (3 x x 1019 Hz)
High frequency radiation. X-rays can penetrate most substances. Lead is one substance that stops the energy.
X-rays have helpful applications in medicine and other fields.
However, they are dangerous and can cause cellular damage at the DNA level.
Earth’s atmosphere absorbs most of the harmful x-rays from outer space
However, this makes it hard to view the x-ray sources from ground-based telescopes.
The most efficient x-ray telescopes are in orbit, outside earth’s atmosphere

6. Chandra is an orbiting, x-ray observatory for observing x-ray sources from space

7. X-RAY TELESCOPE

8. X-ray sources in outer space:
Galaxy clusters
Active galactic nuclei (AGN)
Supernova remnants
Stars
The Moon
Galaxies
Pulsars
X-ray binaries
(binary stars containing a white dwarf, neutron star or black hole).

10. Chandra is a great advance in x-ray telescope technology.
Notice the difference in the Einstein Telescope and Chandra

11. Gamma Rays (> 3 x 1019 Hz)
The highest frequency of all electromagnetic radiation.
It is extremely dangerous,
The earth’s atmosphere protects us from gamma rays, which cannot penetrate it.

12. Gamma Rays are produced in:
Pulsars
Magnetars
Quasars
Active galaxies
Supermassive black hole
Gamma-ray bursts

14. Atmosphere and the Electromagnetic spectrum
How does our atmosphere help us?
Atmosphere and the Electromagnetic spectrum

16. The temperature of the object giving off waves determines the type of waves we detect.
Hotter objects give off higher frequency waves, cooler objects give off lower frequency waves

17. Opacity Opacity is the condition of something that lacks transparency.
Not letting light / energy through
Opposite of transparency
High opacity
Low opacity
High transparency
Low transparency

18. Atmospheric Opacity to Radiation
Short wavelengths
Long wavelengths
Compton Chandra Hubble Spitzer
Visible light observable from Earth with some atmospheric distortion
Most infrared radiation absorbed by atmospheric gases (best observed from space)
Radio Waves observable from Earth
Long wavelength radio waves are blocked
Gamma rays, X-rays and ultraviolet light blocked by the upper atmosphere (best observed from space)
NRAO 140° Telescope
Atmospheric
Opacity
Wavelength
0.001 nm nm nm nm nm μm μm μm mm cm cm m m m km
Gamma
Gamma
Radio
X-Rays
Infrared
Rays
Ultraviolet
Microwaves
(Short Radio)
High Frequency
Low Frequency
Visible
The best place to observe is outside the earth’s atmosphere

19. Atmospheric Opacity to Radiation
Long wavelengths
Atmospheric
Opacity
Wavelength
0.001 nm nm nm nm nm μm μm μm mm cm cm m m m km
The best place to observe is outside the earth’s atmosphere

20. Review What is radiation?
How is the Electromagnetic Spectrum organized?
What are the parts of waves?
What are the types of Electromagnetic radiation?
What role does atmosphere play in the observation of the different types of e.m.r?

21. Finish the notes
Color Code
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