Download Using the Electromagnetic Spectrum

Objective: Students will explain the need
for observing the universe using different
wavelengths and will be able to relate
wavelength, frequency, and energy
The Electromagnetic Spectrum
Why look at the Universe through
different wavelengths?
We get different information depending on how we
observe it. Think of what different things you learn by
using different senses when exploring something.
Smell
touch
Taste
Sound
Sight
Wavelength, Frequency, and Energy
Notice how small is the visible light
section of the entire EM spectrum.
Crab Nebula as seen from different wavelengths
The new Chandra X-Ray Telescope has recorded detailed pictures of the heart of the
Crab Nebula, first seen on Earth in the year 1054. Here are pictures of the Crab at x- ray
(Chandra), optical (Palomar), infrared (Keck), and radio (VLA) wavelengths.
Arecibo Observatory - Radio
Puerto Rico- The observatory's 1,000 ft (305 m) radio
telescope is the world's largest single-aperture telescope.
The Very Large Array - Radio
New Mexico - The observatory consists of 27
independent antennas, each of which has a dish
diameter of 25 meters (82 feet) and weighs 209 metric
tons. The antennas are arrayed along the three arms of
a Y-shape (each of which measures 13 miles long)
South Pole Telescope - Microwave
Antarctica – A 10
meter diameter
designed for
observations in the
microwave region,
with the particular
design goal of
measuring the
faint, diffuse
emission from the
cosmic microwave
background.
W.M. Keck Observatory – Vis, IR
Hawaii –at the
summit of Hawaii’s
dormant Mauna
Kea volcano
It has twin telescopes
-optical & infrared.
The telescopes
operate together to
form a single image
Images from Keck
On left: Mosaic false-color image of thermal heat emission from Saturn
and its rings. The black square at 4 o'clock represents missing data.
Spitzer Space Telescope - IR
Space - The Spitzer Space Telescope is an
infrared space observatory launched in 2003
Images from Spitzer
The Helix Nebula, often photographed for its colors and
resemblance to a giant eye.
Image from Spitzer
Images of the stormy atmosphere of a brown dwarf, creating a
detailed "weather map“ for this class of cool, star-like orbs.
(This image is a composite of Spitzer and Hubble data.)
Palomar Observatory - Visible
California - this observatory operates several telescopes,
including the famous 200-inch Hale Telescope (5.1 m)
Images from Palomar
On right: IC 410, IC 405 (Flaming Star Nebula), and environs. This image is a composite
from B&W images. The images were recorded on 2 types of photographic plates,
one sensitive to red light and the other to blue, and then digitized. Credit: David De
Martin
Hubble Space Telescope – Visible, UV
Space- This
telescope was
carried into a low
earth orbit by
the space shuttle
in 1990.
Hubble's four
main instruments
observe in the
near UV, Visible,
and Near IR.
Images from Hubble
•
•
image of the nearby spiral galaxy Messier 74. Bright knots of glowing gas light up
the spiral arms; regions of new star birth shining in pink.
On right- this is commonly known as the Sombrero galaxy because in visible light,
it resembles the broad-brimmed Mexican hat. However, in Spitzer's IR view, the
galaxy looks more like a "bull's eye.“ This image is a composite of both telescopes.
Chandra X-ray Observatory
Space - The Chandra X-ray
Observatory is the
world's most powerful
X-ray telescope. Since
the earth’s atmosphere
absorbs the vast
majority of X-rays, they
are not detectable from
Earth-based telescopes.
Images from Chandra
“Chandra has allowed astronomers to watch a young neutron star cool steadily over
time. By giving us a snapshot of the temperature roughly every two years for the
past decade.
Compton Gamma Ray Observator
Space – operated in Earth’s orbit from 1991 to
2000. It featured four telescopes in one
spacecraft covering x-rays and gamma-rays
Images from Compton
This computer processed image represents a map of the entire sky. These gamma-ray
photons are more than 40 million times more energetic than visible light photons
and are blocked from the Earth's surface by the atmosphere. A diffuse gamma-ray
glow from the plane of our Milky Way Galaxy is clearly seen across the middle.
Why are all these telescopes in space,
or remote places on Earth?
Because astronomers are anti social.
Because astronomers like to go to exotic places to
do their work.
To reduce the interference from the atmosphere and
the electromagnetic signals from human activity.
The Electromagnetic Spectrum
You need to
memorize
these in
order!
Let’s learn some details!
Speed of Light
All light travels at the speed of light (c) which is:
C= 3.0 X 108 meter/sec
or 186,000 miles/sec
Wavelength, Frequency, and Energy
Wavelength – The distance from one point
on a wave to the same point on the next
wave. (Symbol = λ )
The units are in meters. It can be kilometers
to picometers.
Frequency – The number of waves that pass
by in a given time period .(Symbol = ν or f )
The units are 1/sec or hertz (Hz)
As the wavelength increases, the frequency decreases (& vice versa).
They are INVERSELY related through the equation: c=
Energy
Light with the highest
energy has the
highest frequency,
but the
smallest wavelength.
The equation that relates
energy to frequency is
E = h
where h= 6.626 X 10-34 Jsec
1.
Which color light has the longest wavelength?
A) Red
B) Green
C) Blue
2.
Which color light has the highest frequency?
A) Red
B) Green
C) Blue
3. Which color light has the highest energy?
A) Red
B) Green
C) Blue
4. Which color light has the greatest speed?
A) Red
B) Green
C) Blue