Transcript Telescopes & Electromagnetic Radiation

Big Question:
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do astronomers study light?
Telescopes
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Tools for collecting and analyzing
electromagnetic radiation (light) in ways
beyond what we can do with our eyes alone
Properties of Telescopes
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Aperture: how well the telescope can collect the light.
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Larger aperture = more light collected (brighter image)
Resolution:
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The ability to distinguish small details of objects
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http://www.ifa.hawaii.edu/users/lin/ast110-6/applets/angular_resol_car_lights.htm
Magnification: how much it can magnify the image.
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Depends on combination of lenses/mirrors
Not as important
Comparing the 2 Types of Optical Telescopes
Refracting Telescope
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Invented by Hans Lippershey, but perfected by Galileo
uses lenses to gather and bend visible light, making
things seem larger.
Can be a combination of convex (curved outward) or
concave (curved inward) lenses
An objective or primary lens collects light and sends
it to a smaller eyepiece or secondary lens at the back
of the telescope tube.
Not used much today
Reflecting telescopes
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First developed by Isaac Newton
Focus light by “bouncing” it off of mirrors
Most commonly used type of telescope today
A Better Type of Reflector
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A Cassegrain design uses a second mirror to reflect the
light back through a hole in the primary mirror, and is very
common in research telescopes.
The detector(s) can be placed behind the mirror in a
convenient location for making adjustments
Can be combined with lenses to improve image further
First Light Project
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Images taken by Cassegrain Reflector with 20” primary
mirror
Images taken in black and white using a variety of filters
Filters function to view certain colors in an image. For
example, the Blue Filter (B) will allow mostly blue light
through and absorb the other colors (or wavelengths).
The Z Filter (Z’) is for wavelengths in the near-infrared
part of the spectrum. The Visible Light Filter (V) is for
wavelengths in the middle of the visible spectrum like
yellow and green.
Jupiter- feedback from FTN team
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“Your facts are terrific in your justification. Studying our solar
system is definitely important to our understanding of how it
was formed, the differences in the types of planets, and how to
compare that to exoplanet systems around other stars.
Jupiter is also important to astronomical history. When Galileo
was observing Jupiter in the early 1600s, he discovered its four
largest moons, now called the Galilean moons (Europa,
Ganymede, Calisto, and Io). The importance of these moons,
however, was that they introduced the concept that objects
were orbiting other planets, suggesting Earth wasn’t the center
of the solar system, as had been previously thought.”
In the Jupiter images the B filter images show more of the
cloud banding detail, whereas in the z’ filter image, two of the
four Galilean moons are visible.
Jupiter with B filter
Jupiter and two Galilean
Moons with Z filter
NGC 4414- feedback from FTN team
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“Though small, this is a nice, bright galaxy to observe.
Indeed, Supernova 2013 df was discovered in June of 2013
by four Italian amateur astronomers who are members of
the Italian Supernova Search Project. It was only the
second SN to be recorded in NGC 4414, the first was in
1974. Unfortunately, while SN2013df reached an apparent
magnitude of 13 at the time, its brightness has now
decrease beyond what we will discern with the FTN
telescope.”
NGC 4414 with V filter
M104 (Sombrero Galaxy)
– feedback from FTN team
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As you stated, this galaxy is known for its edge-on view of
the very bright core and broad ring of obscuring dust. It is
one of the largest galaxies at the southern edge of the
Virgo Galaxy Cluster. It was also the first galaxy found to
have a large redshift in its spectrum, meaning it is moving
away from us at high speeds. Originally thought to be a
faint nebula within our own galaxy (when discovered in
the 1780s), this discovery helped to determine that M104
was outside of the Milky Way and in fact another galaxy.
M104 with R filter
(Sombrero Galaxy)
M51 (whirlpool galaxy)
– feedback from FTN team
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“Great justification and research. In most images, the
companion galaxy M51b (NGC5195) appears to be
attached or tugging on one of the arms (you’ll see this
effect in your data), but from a detailed Hubble Telescope
image taken in 2005, it was determined that NGC 5195 is
actually passing behind the Whirlpool”
Compare the M51 images. Can you see that the image
with the B filter shows some brighter splotches in the
spiral arms? Those are areas of “recent” star formation
where new, bright blue (HOT!) stars have been formed in
clusters.
M51 B filter
M51 V filter
Buhl Observatory Sky Watch
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http://www.carnegiesciencecenter.org/planetarium/buhlplanetarium-skywatch/
Ground-Based Optical Telescope:
Yerkes Observatory
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A 40 inch refracting
telescope is located
inside the Yerkes
Observatory at
University of Chicago.
It was created in 1897
and remains the
largest refracting
telescope ever used.
Ground-Based Optical Telescope:
The Keck Observatory
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Mauna Kea, Hawaii
Largest optical telescope (visible light) until 2009
Twin telescopes with 10m wide mirrors
Mauna Kea is the highest peak in the Pacific and is home to 12
telescopes.
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Why?
Adaptive Optics
In modern ground-based research telescopes, a computercontrolled mirror support adjusts the mirror surface many
times per second to compensate for distortions by
atmospheric turbulence
Beyond Visible Light…
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Many modern day telescopes do not use visible light to
collect images
They collect other wavelengths of light from the
Electromagnetic Spectrum
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radio waves, x-rays, infrared, etc
The Helix Nebula
in different wavelengths
Infrared light
Visible light
Ground-Based Radio Telescopes
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A large dish or network of dishes focus the energy of
radio waves on to a small receiver
Largest telescopes ever constructed
Examples:
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ALMA - Atacama Large Millimeter Array
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VLA- Very Large Array
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Atacama desert in Chile
66 networked radio telescopes
New Mexico
27 networked radio telescopes
Arecibo Observatory
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Puerto Rico
Largest ever built-- 1000 ft across, 167 ft deep, covers 20 acres of land
Arecibo Observatory,
featured in the Bond
movie “Goldeneye”
VLA Observatory, featured in
Contact and a Transformers
movie
Interferometry
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Technique of using an array of telescopes to collect
multiple beams of light at one time
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High resolution/detail
Used to measure dimensions of very distant objects
ALMA image showing planet formation
around HL Tauri
VLA image of Cygnus A
(a galaxy emitting strong radio waves)
Problems with Earth based telescopes
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Earth’s atmosphere reflects or absorbs certain
wavelengths
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Earth’s atmosphere blurs images
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our atmosphere and magnetic field serves as a shield for xrays, gamma rays and most UV light
the bending of light by the atmosphere depends on the
temperature of the “air”
“twinkling” (shimmering) effect
“Light pollution”
Solution? Put the telescope in space.
Hubble Space Telescope
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Launched in 1990, 380 miles
above Earth
Named for American Astronomer
Edwin Hubble (1889-1953) who
discovered the expansion of the
universe
Reflecting telescope - Collects
visible light, infrared, and ultraviolet
Primary mirror is 8 feet across
Chandra X-ray Telescope
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NASA launched it in 1999
Orbits Earth 200 times higher
than Hubble
Resolving power: equal to reading
a road sign from 12 miles away
Contains special grazing-incidence
mirrors (because x-rays can pass
through normal mirrors)
Looks at quasars, binary stars, and
black holes
Chandra video
Spiral galaxy M106
James Webb Telescope
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A large infrared telescope
Will be launched in 2018
6.5 meter mirror
Longer wavelength
coverage and better
sensitivity than the
Hubble
Will observe galaxy &
star formation and
potential for life on
other planets
https://www.youtube.com/watch?v=X
1m68NSaTYs
Disadvantages of Space –based telescopes
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Expensive to launch and maintain
Difficult to repair
Short life span
Spitzer - infrared
Fermi- Gamma Ray
Same Space -- Different Light
Radio
Infrared
Optical
X-ray
Orion Nebula -- Hubble and VLA/GBT
X-ray image of a supernova in the
large Megallanic Cloud
Optical telescope image of same
supernova in Megallanic Cloud
Radio telescope image of same
supernova in Megallanic Cloud
X-Ray
Optical
Radio