The Universe Tonight
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Beyond the International Year of Astronomy 2009: From Galileo to the Subaru Telescope, and Moving Toward the Future
By Dr. Kumiko Usuda, Outreach Scientist at Subaru Observatory, NAOJ
Why do we look up at the night sky and wonder about the Universe? People have developed and studied astronomy because we want to know the "world" in which we live and to find answers for some fundamental questions: Where did we come from? Where are we going? In order to answer these questions, we have been studying the Universe by using an appropriate tool: the telescope. In 1608 a Dutch optician combined two lenses and invented the telescope. In the following year, 1609, Galileo Galilei, an Italian scientist, heard about the invention and made his own telescope. He pointed his telescope to the night sky and discovered craters on the Moon, four moons around Jupiter, the waxing and waning of Venus, and a multitude of stars that make up the Milky Way. Galileo was surprised to observe so many new things that no one had seen before. His observations changed the prevailing picture of the Universe.
The invention of a new observational technology often leads to new discoveries, e.g., new objects or details of an object's structure, which then may change beliefs about the Universe. New discoveries generate new questions. Consequently, scientists and engineers try to develop innovative technology to answer issues raised by the new questions. The iteration between a discovery and technological innovation has stimulated the evolution of the astronomical telescope. Over the past 400 years, technology has enabled us to make larger telescopes. The Subaru Telescope atop Mauna Kea is one of the world's largest optical and infrared telescopes; its aperture is about 300 times larger than those of Galileo's telescopes. With the 8.2-m (27 ft) primary mirror, Subaru can see objects about 100,000 times fainter than Galileo's telescopes can. Subaru has found the most distant galaxies, thanks to its light-gathering power and the Prime Focus Camera with wide coverage of the sky. In the future, larger telescopes may enable us to find more distant galaxies in the early Universe.
In the midst of the telescope's 400-year history, spectroscopy, a breakthrough technique, was established for analyzing light. Joseph von Fraunhofer, a German scientist, developed the spectroscope and discovered Fraunhofer Lines in the spectrum of the Sun in 1814. When we divide sunlight with a prism, we see a rainbow spectrum. By observing a spectrum and studying lines, astronomers can obtain information of a star or a galaxy such as its existing elements, temperature, or motion. Today astronomers and engineers have developed a multi-object spectrograph (MOS), which can observe spectra of multiple objects at the same time. For example, Subaru's Fiber Multi-Object Spectrograph (FMOS) can obtain up to 400 spectra at one time.
In the first 300 years of the history of the telescope, scientists only studied outer space in visible light. Radio astronomy started in the United States in 1931 and then, the first infrared and X-ray telescopes have followed. When we observe an object in different "lights", that is, in different electromagnetic waves, we see different things. Using radio and infrared telescopes, we can observe gas and dust, the materials that stars are made of. By using X-ray telescopes, we can detect active and burned-out stars.
Dr. Kumiko Usuda completed her Ph.D. thesis and graduated from the Graduate School of Department of Astronomy, Faculty of Science, University of Tokyo, Japan in 1998, and moved to Hilo with her husband. After her children were born in Hilo, she visited her children's preschool to talk about outer space, and started a new career. She was affiliate research fellow at Subaru Telescope, NAOJ until 2006 before moving to the PIO (Public Information and Outreach) office of Subaru. Her job as astronomical education and public outreach takes her into the local community visiting a lot of classrooms, having science workshops at Ellison Onizuka Science Day, and other events. She also shares hands-on activities at teacher training workshops.