Since 2000, the National Astronomical Observatory of Japan (NAOJ) has been operating one of the largest and most sophisticated telescopes in the world at the summit of Mauna Kea in Hawaii. The Subaru telescope saw first-light (i.e. started observing) early in 1999 and is currently conducting routine research. Along with other observatories around the world, is making many important discoveries about the Universe we live in.

Some facts about the telescope:

• Observatory location: Mauna Kea, Hawaii
• Height above sea level: 4,139 metres (13,580 feet)
• Moving Mass: 600 metric tonnes
• Mirror diameter: 8.3 metre

Rather than the normal dome shape, the Subaru enclosure is cylindrical and rotates as one with the telescope. It is designed to reduce atmospheric thermal turbulence that can result in the telescope producing poor images. It does this by having special ventilation grills that open at night to funnel the air through the enclosure.

The most significant feature of Subaru is its relatively thin (23cm) primary mirror. With a diameter of 8.3 metres, this makes the mirror fairly flexible, and allows astronomers to attach 261 computer-controlled pressure supports and sensors. These monitor the mirror and automatically push it back into the correct shape. This method is called adaptive optics and can also be used to correct problems caused by Earth's atmosphere.

The following two images are good example of the power of Subaru. The image on the left is of the Helix nebula, which is a planetary nebula in the final stages of its lifetime. The image on the right is a typical spiral galaxy.

The Helix Nebula - NGC 7293

A typical spiral galaxy