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.
Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.
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
All light travels through space at the same speed -- The Speed of Light -- 300,000 kilometer/second !!!
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??
Fortunately, gamma rays, x-rays and much UV light are absorbed by Earth's atmosphere -- sparing us from harm
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
Galileo Improved the Refracting Telescope to observe visible light
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
-- visible light is refracted (bent) as it passes from air into materialof a different density.
-- white light bent by glass prism is spread into rainbow
-- through water too!
You can blend colors back into white light too!
-- Lenses can be arranged to refract (bend) lightin ways that make objects appear larger than they are.
Convex Glass Lens
-- The lens tricks the brain into thinking the object is larger than it is
-- Object is magnified
Chromatic Aberration is a problem with refracting lenses
-- white light is separated into colors of the rainbow
-- creates image blurry with rainbows at edges
Sir Isaac Newton developed Reflecting lens Telescopes
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
Reflecting Telescope uses mirrors to gather and focus light
Mirrors focus light by reflecting it, NOT refracting it
Modern Telescopes Are Designed to Observe Specific Bands of Light
Since our atmosphere is transparent to Radio Waves we can position radio telescopes on Earth
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
Arecibo also emits radio waves that bounce off near-Earth asteriods and back to the telescope so we can keep track of how close they come to Earth!
Click here to see a radio image of an asteroid taken by the Arecibo radio telescope
The South Pole Telescope observesmicrowave light from space. It is located in Antarctica because the altitude is very high and the air is very dry. The atmosphere on mountain tops is much thinner and thus is more transparent tomicrowaves. Moisture in the air is a very effective blocker of microwaves.
Image of the “CosmicMicrowave Background” energyleft over from the formation of the Universe 13.75 billion years ago – aka, the “Big Bang”
Spitzer Space Telescope – designed to detect theinfrared light emitted by the cooler gas of Nebulas (the remains of supernovae) and the rings of Jupiter, Saturn, Uranus and Neptune
Earth's atmosphere absorbs most infrared light, so infrared telescopes are designed to orbit Earth above the atmosphere
Image of Saturn’s largest ring – made by Spitzer
Hubble Space Telescope has orbited above Earth’s atmosphere for over 20 years – taking pictures of the visiblelight emitted and reflected by objects in space
Although our atmosphere is transparent to visible light, Hubble takes much clearer pictures because it is above the atmosphere
Hubble Ultra Deep Field of the many Galaxies in our region of the Universe
SOHO Solar Space Telescope – detects UV lightemitted by the Sun
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 of the UV light emitted by the Sun taken by the SOHO space telescope, showing a large ejection of energy and particles in the upper right quadrant of the Sun.
Image is colorized to help us see different wavelengths within the band of UV light
Chandra Space Telescope
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
Infrared image of the famous “Crab Nebula” taken by the Spitzer Space telescope. It shows the cooler dust swirling around the remains of an exploded star
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
Hubble Space Telescope Video