Star gazing

Far from the light pollution of cities, mountains are the ideal place to watch the stars and planets in the velvety sky. Discover the joys of astronomy with an astronomical telescope, or any other suitable observation system, and some good advice from a guide from the National Union of Mountain Guides.

Some Mountain Guides specialise in astronomy. They organise "astronomy treks" in the mountains with specially adapted instruments.

While Galileo invented the first astronomical telescope, which Newton improved with his reflecting telescope, some guides today use a far more powerful telescope which can be carried into the mountains in "backpack" mode.

This telescope, which is hand made and custom built in France has been designed for mobile astronomy. It is therefore practical for the mountains, but also for treks and tips far away in the mountains or deserts around the world, sites which are particularly good for observation. With its 30cm diameter mirror it provides 450x magnification in absolute terms.

Before you begin observing, the telescope must be collimated. This consists of aligning the mirrors with each other using a laser. The light capturing potential and the sharpness of the observed image depends on everything being perfect aligned.

That familiar celestial body, the Moon is magnified 100 times here. This photo shows it 4,000 kilometres away, instead of the usual 400,000 kilometres that separate it from us (about 1.28 light-seconds). © Erwan LE BERRE

Saturn is much further away (1,322 million km) and magnified 200 times here. For celestial bodies which are so far away, the telescope must be motorised so it can be calibrated to be in perfect alignment with the earth's rotation. An SLR camera, with its lens removed is simply fitted to the telescope, which becomes its lens. The motor which moves a few millimetres at a time will allow a long enough exposure time to capture the low light levels. © Erwan LE BERRE

Captured with a non-portable telescope, the Orion Nebula is the jewel of the winter night sky in our hemisphere. It is a true interstellar nursery where stars and planets are born "live" under the watchful eye of the astronomer. Or rather with a "slight delay" of 1,300 years since this constellation is located about 1,300 light-years away. © Erwan LE BERRE

The directory on the National Union of Mountain Guides website lets you identify the registered professionals specialising in astronomy (search by activities/ specific features and then "astronomy"). They will share their knowledge with you throughout the year, beyond the period of the so-called "Night of Stars" at the beginning of August.