Focus Question: How do astronomers study light?

Telescopes

Focus Question: How do astronomers study light?

Telescopes Tools for collecting and analyzing electromagnetic radiation (light) in ways beyond what we can do with our eyes alone

Properties of Telescopes Aperture: how well the telescope can collect the light. Larger aperture = more light collected (brighter image) Resolution: The ability to distinguish small details of objects http://www.ifa.hawaii.edu/users/lin/ast110-6/applets/angular_resol_car_lights.htm Magnification: how much it can magnify the image. Depends on combination of lenses/mirrors Not as important

Optical Telescopes Studying Visible light

Refracting Telescope Perfected by Galileo Uses lenses to gather and bend visible light Can be a combination of convex (curved outward) or concave (curved inward) lenses A primary lens collects light and sends it to a smaller secondary lens at the back of the telescope tube. Not used much today Primary Lens Secondary Lens

Refracting Telescope: Yerkes Observatory 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.

Reflecting telescopes First developed by Isaac Newton Focus light by bouncing it off of mirrors

A Better Type of Reflector A Cassegrain design uses a second mirror to reflect the light back through a hole in the primary mirror Invented in 1672, this design is the most common in research telescopes today. The detector(s) can be placed behind the mirror in a convenient location for making adjustments

Mauna Kea Observatories There are currently thirteen working telescopes near the summit of Mauna Kea: nine for optical and infrared astronomy three for submillimeter wavelength (microwave) astronomy one for radio astronomy

The Keck Observatory: A Ground-Based Optical Telescope Mauna Kea, Hawaii Twin telescopes with 10m wide mirrors that work together World s largest optical telescope until 2009 now the biggest single reflector is the Gran Telescopio Canarias (GTC) in Spain

Keck Headquarters Astronomers don t actually work at the telescopes on the summit They sit in the remote operations room in the town of Waimea, about 2 hours away and the data is sent to a computer

Model of Keck I Primary Mirror

The grass area behind us represents one of the mirror segments My new buddy David, who works at both Keck headquarters in Waimea and at the telescopes on Mauna Kea

Problems with Ground-based telescopes Earth s atmosphere reflects or absorbs certain wavelengths our atmosphere and magnetic field serves as a shield for x- rays, gamma rays and most UV light Earth s atmosphere blurs images the bending of light by the atmosphere depends on the temperature of the air twinkling (shimmering) effect Light pollution from artificial light sources make it hard to see very faint objects in space

Getting Better Images Telescopes are built on mountaintops so that they are above much of the atmosphere Telescopes are built in remote areas where there isn t much artificial light Modern ground-based telescopes use two newtechnologies: Interferometry Adaptive Optics

Interferometry Technique of using an array of telescopes to collect multiple beams of light at one time High resolution (detail) Used to observe very distant or faint objects

Adaptive Optics Computer-controlled mirror supports adjust the mirror surface many times per second to compensate for distortions by atmospheric turbulence and increase resolution power

Other Types of Telescopes Beyond visible light

Beyond Visible Light Many modern day telescopes do not use visible light to collect images They collect other wavelengths of light from the Electromagnetic Spectrum: radio waves, x-rays, infrared, etc

Ground-Based Radio Telescopes A large dish or network of dishes focus the energy of radio waves on to a small receiver Largest telescopes ever constructed Examples: ALMA - Atacama Large Millimeter Array Atacama desert in Chile 66 networked radio telescopes VLA- Very Large Array New Mexico 27 networked radio telescopes Arecibo Observatory Puerto Rico Largest ever built-- 1000 ft across, 167 ft deep, covers 20 acres of land

Space-Based Telescopes

Space-Based Telescopes Advantages: No distortion by Earth s atmosphere Able to study all wavelengths of light Disadvantages: Expensive to launch and maintain Difficult to repair Short life span

Hubble Space Telescope Launched in 1990, orbits 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 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 Spiral galaxy M106

Other Space Telescopes Spitzer infrared light Fermi- Gamma Ray

Telescopes of the Future

James Webb Telescope 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 James Webb video clip Building the JWST

Thirty Meter Telescope (TMT) Proposed ground-based telescope with a 30-meter primary mirror, the largest ever built Planned for construction on Mauna Kea in 2015 but delayed and surrounded in controversy after protesters blocked the site Incredible resolution would allow astronomers to study very faint and distant objects and learn about: Star formation Exoplanets Supermassive black holes Evolution of the universe http://www.cnn.com/2015/08/27/us/tmt-hawaii-telescopecontroversy/index.html

Potential Scientific Advancement A 30-meter telescope, operating in wavelengths ranging from the ultraviolet to the mid-infrared, is an essential tool to address questions in astronomy ranging from understanding star and planet formation to unraveling the history of galaxies and the development of large-scale structure in the universe. -- TMT website

Cultural/religious beliefs Mauna Kea is home to many archaeological burial sites Shrines and temples are located near the summit Modern Native Hawaiians continue to regard Mauna Kea with reverence and many cultural and religious practices are still performed there.

Community support: malama means take care of or protect

Land Rights: The upside-down Hawaiian Flag symbolizes the belief that Hawaii was illegally annexed by the US in 1959

Greater financial impact $1.4 Billion construction project Estimated 300 temporary construction jobs 120 permanent jobs once the facility opens Hawaii s economy has struggled since the 2008 crash

Environmental Impact Possible damage to the habitat of the Wekiu bug, an indigenous insect that was just recently removed from the endangered species list The Silversword plant species became an endangered species due to cattle, sheep, and goats lower on the mountain Potential for contamination of the Mauna Kea aquifer, which supplies water to the east side of Hawaii Island

What do You think? Should the TMT be built on Mauna Kea?

The Latest News As of October 30 th, 2016 the TMT Board of Governors has identified a site in the Canary Islands of Spain as the primary alternative to Hawaii. In January 2017, a state circuit court judge ordered a new hearing allowing residents to contest the issuance of a building permit on public lands "Mauna Kea continues to be the preferred choice for the location of the Thirty Meter Telescope, and the Board will continue intensive efforts to gain approval for TMT in Hawaii.

http://www.hawaiinewsnow.com/story/31193881/thirtymeter-telescope-officials-considering-sites-outside-ofhawaii