1. Astronomers Observe Light Radiated Toward Earth By Matter in Space 2. Light is Energy That is Radiated as a Wave with both Electric and Magnetic Properties 3. The Electromagnetic Spectrum Shows All Light Grouped in BANDS organized by wavelength. Short wavelength High energy.
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2. Light is Energy That is Radiated as a Wave with both Electric and Magnetic Properties
3. The Electromagnetic Spectrum Shows All Light Grouped in BANDS organized by wavelength
The distance light travels in one year is called a Light Year -- about 10 trillion kilometers
Our galaxy -- the Milky Way -- is about 100,000 light years in diameter and contains more than 200 billion stars!!
The nearest star system to our Sun is Alpha Centauri -- about 4.2 light years away!! How many kilometers is that??
Earth's atmosphere is transparent (like a window) only to certain bands, including:
Optical Window – some UV light, all visible light and some infrared light
Radio Window – some radio waves and some microwaves
Refractors use curved glass lenses to magnify objects up to 30x
Visible light is refracted (bent) as it enters and exits a curved glass lens
-- white light bent by glass prism is spread into rainbow
-- through water too!
You can blend colors back into white light too!
Convex Glass Lens
-- The lens tricks the brain into thinking the object is larger than it is
-- Object is magnified
-- white light is separated into colors of the rainbow
-- creates image blurry with rainbows at edges
Reflector Telescopes usemirrors (instead of glass lenses)
TwoAdvantages of reflecting telescopes:
1. No Chromatic Aberration – no separation of white light into colors of the rainbow
2. Mirrors weigh less than glass lenses
Universal Law of Gravitation
All objects in the universe exert a force on each other that is related to the mass of the two objects and the distance between them
This force is gravity
Mirrors focus light by reflecting it, NOT refracting it
Arecibo Radio Telescope in Puerto Rico – located on a mountain and dug into the ground facing up so that it only detects radio waves from space, not radio waves emitted by radio stations. Radio waves are very long, so receiver must be very wide and it does NOT have to be a smooth surface
Click here to see a radio image of an asteroid taken by the Arecibo radio telescope
Earth's atmosphere absorbs most infrared light, so infrared telescopes are designed to orbit Earth above the atmosphere
Although our atmosphere is transparent to visible light, Hubble takes much clearer pictures because it is above the atmosphere
SOHO helps astronomers predict dangerous "space weather" caused by massive ejections of particles and energy by the Sun.
Space weather can cause satellites to fall out or orbit, expose airline passengers to be exposed to high doses of radiation and cause electrical blackouts on Earth.
Image is colorized to help us see different wavelengths within the band of UV light
Designed to detect X-raysemitted by the hottest objects in space such as neutron stars and black holes
All space X-rays are blocked by our atmosphere
Image of the same “Crab Nebula” taken by the Chandra X-ray telescope. The central white star spewing a jet of x-rays is clearly visible