November 22, 2015
By Sean Adkins
Every night, all over the world, people look up at the sky and wonder about the distant stars. Here in Hawaii we have the privilege of looking up at a very dark sky, but even here with the naked eye we can only see a few thousand stars. This is mainly because of the small size of the lens in our eye, which limits the amount of light it can gather, and also limits the detail we can see for those incredibly distant objects.
This week we will celebrate the 25th anniversary of first light on the Keck I telescope, an event that started the process that has made Hawaii today the best-known place on earth for scientific discovery in astronomy, and the Keck Observatory the home of the two most scientifically productive telescopes on earth.
First light, the first time light from the night sky is focused into an image by a telescope, is a very special event for the community of people required to build and use them, accompanied by a nearly mystical sensation as it culminates years of dedication to completing the project and bringing the Universe a little closer to all humankind.
Since the invention of the telescope 400 years ago, we have been looking at the sky in with much bigger manmade eyes, seeking to learn more and more about our Universe. This has been possible because we have been able to build larger and larger telescopes. For a time telescopes were developed with either lenses or mirrors, but the understanding of telescope design improved, and telescopes using mirrors became the choice for larger telescopes. In 1977 the largest telescope on earth was the Hale telescope at Mount Palomar, with a mirror 5 meters in diameter. Astronomers at the University of California knew that their research was reaching the limit of what could be done with the Hale and smaller telescopes, and so they started a project to design and build a 10 meter telescope. This was a very ambitious goal, since even the Hale was known to have limited performance because of the tendency of its mirror to change shape as the telescope was pointed at different places in the sky.
A 10-meter mirror would be nearly impossible to build, and its weight and cost made the prospect of doubling the size of the Hale seem improbable. But, on November 24, 1990 the Keck I telescope on Maunakea in Hawaii saw first light. It would be a 10-meter telescope made of 36 hexagonal segments, each 1.8 meters across. At first light it only had 9 segments – matching the same size as Hale – with the last of the 36 segments installed 18 months later.
Getting to this point required solutions to many difficult engineering problems, and it is thanks to the incredible efforts of hundreds of people in Hawaii and vision and leadership of astronomer and physicist Dr. Jerry Nelson that solutions were found and Keck I, and then its twin, Keck II were built.
These two telescopes have become the two most scientifically productive telescopes on earth, thanks to the excellent conditions offered by the Maunakea site, and the creativity of the astronomers who use the telescopes.
Discoveries made using the Keck Observatory telescopes include studies of the most galaxies, the confirmation of the accelerating expansion of the Universe, the discovery of a super massive black hole at the center of our galaxy, the understanding that one of every 5 sun-like stars in our galaxy have earth‑sized planets capable of supporting life, and the measurement of the spectrum of the most distant galaxy ever recorded.
Keck Observatory is managed and operated every night by more than 100 members of our communities here in Hawaii. Surprisingly, less than 10 percent of the staff are astronomers, the rest are engineers, programmers, technicians and business and administrative support positions.
The proven segmented mirror design of the Keck Observatory telescopes is now the preferred solution for all other large telescopes, including the next space telescope, JWST, and the even larger ground‑based telescopes astronomers will use to continue exploring our Universe. Hawaii is internationally known as the place where many of the major discoveries in astronomy have been made and we can all be very proud of what we have accomplished fueled from the universal need of humans to discover the heavens.