Optical Astronomy

For much of the history of astronomy, almost all observation was performed in the visual electromagnetic spectrum with optical telescopes. The Earth's atmosphere is relatively transparent to the visible portion of the electromagnetic spectrum, however, the quality of celestial images are hindered by turbulence and thermal variations in the air.  In addition, light pollution from nearby light sources obscure observation of faint objects. 

For observation purposes, the optimal location for an optical telescope is undoubtedly in outer space. There the telescope can make observations without being affected by the atmosphere. The Hubble Space Telescope and the next generation, the James Web Telescope, are direct solutions for the atmospheric problem.
Space Weather

On February 11, 2010, NASA launched the Solar Dynamics Observatory (SDO). This program is designed to understand the causes of solar variability and its impacts on Earth.  SDO is designed to help us understand the Sun's influence on Earth and Near-Earth space by studying the solar atmosphere on small scales of space and time.  To see the Sun's activity in the last 48 hours, click here.

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Space Telescopes are very costly to lift into orbit. Thus, the next best locations are on mountain peaks that possess good atmospheric conditions.  Examples of these peaks with important observational telescopes are: Mauna Kea, Hawaii; La Palma, Canary Islands and Cerro Paranal, Chile. 

Advances in very large mirror manufacturing and the resulting telescopes have vastly improved light-gathering capability allowing very faint magnitudes to be observed. Additionally, the use of adaptive optics, speckle imaging and interferometric imaging have dramatically improved the resolution that can be achieved with earth based optical telescopes.
The Large Binocular Telescope (LBT)
Two 8.4 meter mirrors

The Future of Ground Based Optical Astronomy

The next big breakthrough in Optical Astronomy will be the completion of the Giant Magellan Telescope (GMT).  This telescope will employ six off-axis 8.4 meter or 27-foot segments surround a central on-axis segment, forming a single optical surface with a collecting area of 24.5 meters, or 80 feet in diameter. The GMT will have a resolving power an order of magnitude greater than the Hubble Space Telescope.

The telescope will be located high up on Chile's Atacoma Desert, approximately 8,500 feet above sea level. This location offers superb observing conditions with minimal atmospheric disturbances.
Giant Magellan Telescope
  Artist drawing of finished GMT
The telescope will utilize a very advanced optical system known as "adaptive optics." The telescope's secondary mirrors are actually flexible. Under each secondary mirror surface, there are hundreds of actuators that will constantly adjust the mirrors to counteract atmospheric turbulence. These actuators, controlled by advanced computers, will transform twinkling stars into clear steady points of light. It is in this way that the GMT will offer images that are 10 times sharper than the Hubble Space Telescope. 

Utilizing the GMT, astronomers will be able to observe some of the earliest events that occurred right after the "Big Bang" or origin of our universe.

The GMT will take approximately 10 years to become operational.

A GMT mirror under construction
  8.4 meter mirror under construction