Mauna Kea in Hawaii: Astronomy on the World's Highest Island Mountain Four thousand years ago, a volcano exploded in a far away area of the Pacific Ocean. Today, the Mauna Kea volcano is inactive. It is on the Big Island in the state of Hawaii. It is the highest mountain on any island in the world. It is also the highest mountain in the Pacific Ocean. And it is one of the best places in the world to study the heavens. This is because the air is clear, dry and generally free from pollution. Astronomers from around the world come to the Manna Kea observatory to explore the universe. Go Up to the Mountaintop Astronomers must compete for observation time on Mauna Kea. But visitors are welcome any time. They must either walk up more than four thousand kilometers to the top of the mountain. Or they can join a guided vehicle tour that leaves from the Mauna Kea Visitors Center, about two-thirds of the way up the mountain. Erik West is our guide for the trip up the mountain. Mr. West says visitors who want to drive up the mountain must have a special kind of four wheel-drive vehicle. He also explains some health and safety issues because of the height of the mountain. Being at such a high elevation can affect people's health. Visitors must not have any heart or breathing problems. They must not have dived deep underwater in the past twenty-four hours. And visitors must be over the age of sixteen. Now we are ready to drive our vehicles up the mountain. One behind the other, the cars follow a steep road during the forty-five minute drive. They drive over lava rock created by the volcano when it was active. Tour Around the Astronomy When we reach the top of the mountain, we get out of our vehicles. We see a group of domed observatories that look like a garden of giant mushrooms. The air up here is cool. Mr. West warns that the air can make people sick because it has forty percent less oxygen than at sea level. He says it has different effects on people. Some people feel light-headed, dizzy or sick to their stomachs. If any people get so sick that they need oxygen, they must leave and go back down the mountain. The first large telescope was built on Manna Kea in nineteen seventy. Now there are thirteen groups of observatories. One of them is called SMA, or Submillimeter Array. It includes eight different telescopes that operate together. Eleven countries and several universities are involved with the telescopes. Tile biggest telescopes are the ten-meter Keck telescopes. Mr. West says telescopes keep getting bigger because astronomers want to be able to collect as much light as possible. How the Astronomy Works The Keck One and Keck Two are world's largest optical and infrared 红外线) telescopes. Their mirrors are divided into thirty-six hexagonal(六边形) parts. They work together as one piece of reflective glass. During the day, Keck One is a sleeping giant of steel devices closed inside a protective covering. The dome covering weighs about seven hundred tons. It is about thirty meters to the top of the dome. The whole minor structure is about twenty-four meters tall. The real action begins at sundown. The dome opens and starts rotating to where the astronomers need it. The mirror rotates to the place where they will be observing. Throughout the night, the mirror moves to follow an object as it crosses the sky. But the astronomers are not near the telescopes. They are in the control room keeping warm. Over the years, astronomers have made many important discoveries here. They have discovered new moons around Jupiter (木星). They have taken pictures that help measure the expansion of the universe. They have observed hundreds of small objects orbiting the Sun past the orbit of the planet Neptune(海王星). Mr. Rolf Kudritzki, the director of the University of Hawaii's Institute for A