THE SUN-EARTH-MOON SYSTEM

Chapter 28

•The best tool to study the universe is the light emitted from it – Radiation

•We study Electromagnetic Radiation•Electric and magnetic disturbances traveling through space as waves

•We can only see the visible light part of the spectrum

Electromagnetic Spectrum

• Arranged according to wavelength and frequency

• Type of radiation is classified by its wavelength

Wavelength & Frequency

Wavelength – the distance from one wave to another

Frequency – the number of waves that pass a given point in a certain amount of time

c = λfc = speed of light (3 x 108 m/s or 300,000,000 m/s)λ= wavelengthf = frequency

*Remember ALL electromagnetic waves travel at the speed of light

With this equation, if you know one, you can find easily find the other.

Telescopes•GOAL : To bring as much radiation as possible to a focus

•Benefits1. Modify them to observe all wavelengths2. Collects from distant objects and focuses it to

a point where it can be studied3. Allows use of other special equipment4. Used to make time exposures the human eye

may miss

Visual Telescopes

Visual telescopes are used to focus visible light (also work for infrared and UV)

•Refracting•Reflecting

Refracting Telescopes• 1st used, made around 1600•Uses Lenses•Objective Lens – Largest

Eye Piece Lens Second•When light passes through objective lens, it focuses the light away from the lens.• The larger the objective, the more light it can collect

Refracting Telescope

Reflecting telescopes•Uses mirrors• The larger the mirror, the more light collected• A flat mirror reflects the light to the eyepiece lens•Most telescopes used today

Reflecting Telescopes

X-Ray Telescopes

• Can’t be focused by normal mirrors because x-rays aren’t easily reflected• Arrangement of cylindrical mirrors allows x-rays to be guided to a precise focus to form an image

Radio Telescopes• Large dish that reflects the waves to focus above the dish