Transcript Galileo, Brahe, and Kepler - Pennsylvania State University

Future Telescopes
Areas of Telescope Advancement
• Gather more light
– Larger mirrors (or many smaller ones)
• Sharper images
– Larger mirrors or arrays of mirrors
– Correct for blurring of atmosphere (adaptive optics)
– Space satellites (e.g., Hubble)
• Images of larger areas
– Specially-designed telescope optics
– Cameras with large detector arrays
• More sophisticated instruments
– High spectral resolution
– Multi-object spectroscopy
– Adaptive optics
Day
Night
The largest single mirrors are currently 8 m in
diameter. Rather than use larger mirrors, future
telescopes will contain arrays of mirrors.
Smaller mirrors are easier and cheaper to build,
so larger telescopes often use segmented mirrors
The largest optical/IR telescopes currently have
mirror diameters of 10 m. The next generation of
telescopes should reach 30-100 m
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Improvement in resolution from 1 to 100 m
Large Synoptic Survey Telescope (LSST)
LSST is a 8.4 telescope that will use a wide-field camera to image
2/3 of the sky 1000 times at optical wavelengths from 2016-2026.
The primary goals are the discovery of all large near-Earth asteroids
(>100 m) and measurements of dark energy.
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LSST camera
Searching for Asteroids with LSST
Imaging through a perfect telescope
FWHM ~l/D
in units of l/D
Point Spread Function (PSF): intensity
profile from point source
With no turbulence, FWHM is
diffraction limit of telescope,
~ l/D
Example:
l / D = 0.02” for l = 1 mm,
D = 10 m
With turbulence, image size gets
much larger (typically 0.5 2”)
How does adaptive optics work?
Measure details of
blurring from
“guide star” near
the object you want
to observe
Calculate (on a
Light from both guide
computer) the
star and astronomical
shape to apply to object is reflected from
deformable mirror
deformable mirror;
to correct blurring distortions are removed
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Comparison of normal seeing and AO
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Neptune with AO on Keck (10 m)
Keck AO
2.3 arc sec
normal seeing
Neptune with Hubble and Keck AO
HST
Keck AO
Limitations of AO
• most AO systems are restricted to IR; very difficult in optical
• AO correction applies to only a very small patch of sky
• need bright star near target for wavefront correction, although
lasers can be used to create artificial stars
Stratospheric Observatory for IR Astronomy (SOFIA)
SOFIA is a 2.5 m IR telescope that will soon be deployed
on a modified 747.
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SOFIA will observe at wavelengths that are blocked by the
atmosphere for telescopes on the ground
Example of a SOFIA flight path
Example of a SOFIA flight path
James Webb Space Telescope (JWST)
JWST is a 6.5 m IR telescope that will be launched in 2014. Because
of its large mirror, it will over much better sensitivity and spatial
resolution than any previous IR telescope. It will focus on the first
stars and galaxies, as well as planets around other stars.
Spitzer
JWST
Orbit of JWST
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Atacama Large Millimeter/submillimeter Array
(ALMA)
ALMA will be an array of 54m and 12m millimeter-wave dishes on a
high plain (5000 m) in Chile. It will provide 0.02” resolution at 1mm,
which is comparable to JWST.
Like JWST, ALMA will focus on the first galaxies and the formation
of planets.
The ALMA site
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ALMA science
disk gap created by 5 AU gas giant at 100 pc
ALMA science
Hubble
Nearby galaxies
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Distant galaxies
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ALMA science
ALMA
Nearby galaxies
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Distant galaxies
Square Kilometer Array (SKA)
SKA will be an array of thousands of radio dishes with a total
collecting area of 1 km2 and a baseline of 3000 km. It will be built in
either Australia or Africa and should begin operations in 2020. SKA
will offer both sharp images (<0.1”) and a huge field of view (1 deg),
as well as 100x the sensitivity of VLA. SKA will study interstellar
gas from soon after the Big Bang and the formation of planets.
SKA design
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