Gemini North Telescope

The Gemini project is a multi-national partnership of seven countries that has resulted in two identical 8.1 metre telescopes - one on Hawaii's Mauna Kea mountain (Gemini North) and the other on central Chile's Cerro Pachon mountain (Gemini South). As well as the United Kingdom, the others partners in the project are the United States, Canada, Chile, Australia, Brazil and Argentina. Gemini North began taking observations in February 1999, after 10 years of planning.

Gemini North
Gemini North Telescope
Credit: Gemini

Some facts about the telescope:

  • Observatory location: Mauna Kea, Hawaii
  • Height above sea level: 4,139 metres (13,580 feet)
  • Moving Mass: 342 metric tonnes
  • Mirror diameter: 8.1 metres

This long exposure image (see right) reveals the rotation of the Earth around the North Celestial Pole. Over time the stars seem to trace out circles around the imaginary rotation axis of our planet. Only stars on that axis point will appear to stand still - such as the North Star (Polaris). Whilst we would find it hard to notice any star movement, the rotation is obvious in this 45 minutes exposure.

Image of possible planet
Credit: Gemini

A special feature of the Gemini North Telescope is an adaptive optics system that can rapidly distort the mirror to correct for distortion caused by the Earth's atmosphere. One benefit of this is the ability to separate very distant objects that are very close to each other. Without the correction, they would merge together as one blob, but with the correction, they can be identified as individual objects.

The image to the left appears to show a gas-giant exoplanet in orbit around the star 1RXS J160929.1-210524, some 500 light-years away. However, it will several years of observing this object to ensure that the object is in fact gravitationally tied to the star.