Astronomy Seeing through different light…

VisibleUV..

VisibleIR

VisibleRadioXray

Venus -IR

Venus -UV

Venus -RADIO

Venus -VISIBLE

Types of Light Gamma rays X-Rays UV rays Visible Rays Infrared Microwaves Radio Long Waves

Types of Light Gamma rays –Nuclear blast X-Rays –Go through skin and body, stopped by bone UV rays –Penetrates skin, causes damage

Types of Light Visible Rays –What we can see Infrared –Night vision goggles Microwaves –Excite water Radio Long Waves

Optical Telescopes Why do astronomers use telescopes? –Magnification –Resolution –Brightness

Brightness Gathering light to make faint objects appear bright MOST important Depends on the size of the lens

Resolution How sharp an object looks Larger the lens, higher the resolution HDTV vs. normal tv

Magnification How many times larger an object looks LEAST IMPORTANT

Magnification calculations M = fo/fe Fo = Focal length of the objective Fe = Focal length of the eyepiece

How big is our universe? MONTE PYTHON VIDEO

Optical Telescopes Relflectors and Refractors

Refractors Uses lenses to bend light

Refractor

Objective lens Eyepiece

Focal Length The distance from a lens to the focal point Focal Point The point where light rays converge to produce an in focus image

Two lenses are placed at their focal lengths apart Fo (focal length of objective) + Fe (focal length of eyepiece) = Length of telescope

Fo = 1000mm Fe= 20 mm What is the length of the telescope? What is the magnification?

Activity Right Eye Focal Length: Left Focal length: Both eyes

II. Focal Length of a lens Focal Length of Lens 1: Focal Length of Lens 2:

III. Magnification Draw a small arrow Measure it in cm

Reflector Telescopes Newtonian and Cassegrain

Newtonian Reflector Uses a mirror to reflect light

Newtonian Reflector

Cassegrain Reflector Has eyepiece behind mirror Has a small hole drilled into the middle of the objective mirror so that they light can go through

Cassegrain

Refractors PROS Better resolution due to no diagonal mirror blocking part of the objective CONS Chromatic Abberation (colors smear) Size limit on objective lens - if glass lens is too big it will sag) - max size = 3 feet

Reflectorss PROS No size limit –The objective mirror can be made up hundreds of smaller mirrors Easier to hook up a computer to CONS Slightly less resolution

Optical observatories Keck 1 and Keck II in Hawaii

Hubble Space Telescope

GEMINI in Chili

Places to Build optical observatories Away from cities Away from light pollution Mountain tops or space The more atmosphere a telescope looks through, the blurrier the image

Atmospheric Window Transparent to: Visible and Radio Semi-Transparent to: Infrared Opaque to: UV, X-Ray, Gamma Ray

Radio Telescopes Parts –Dish: :Large dish that focuses the rays (does not have the be smooth) –Receiver: Gathers the rays and send to a computer to analyze

FALSE COLOR IMAGE: –Bright Areas= high intensity –Dark Areas= low intensity RESOLUTION: - Since radio waves are very large, they have very low resolution

Interferometer Array A way to increase resolution Observe the same object with lots of different telescopes Send all data to computer to create a high resolution image

Length of telescope Distance the telescopes are separated

Where to place Radio Telescopes Valleys –Avoids radio interference (mountains block the signal)

Examples of Radio Observatories Arecibo –Worlds largest single radio telescope –Puerto Rico

VLA –Very large array –New Mexico –On Train Tracks

VLBA –Very large Baseline Arrary –Array of the worlds largest telescopes –Size of earth

Infrared Telescopes Uses regular mirrors Must be placed high in the atmosphere

Sophia Aircraft with a telescope built in it

Spitzer In space Studies stars and planet formation

Telescope Videos e_deep_field/

Argons spectra The colored lines on the spectrum come from Argons electrons relaxing back to the ground state and releasing photons Fingerprint/Bar code Each element/compound has unique spectra

Hydrogen Less lines = less energy levels/electrons

Helium

Where should we put telescopes?