Fiona MacLeod focuses on what it is like to work as an astronomer.

Martin Buchan, aged nine, wants to be an astronaut. This car-eer choice has been prompted by a project on space which his class at Coaltown of Wemyss primary school, Fife, has started as part of the Earth, material and solar system element of the five to 14 science curriculum.

He wants to know if Ian Mulvany, the final-year astrophysics student taking the school party around Edinburgh’s Royal Observatory visitor centre, has ever been to space. When Ian says he hasn’t, Martin is disappointed and the conversation is over. He turns to the nearby telescope that dwarfs him by several feet.

The visitor centre on Blackford Hill encapsulates almost a century of star-gazing. The ornately embellished verdigris east tower houses the magnificent telescope built in 1928, which is still operated by a combination of rope pulleys, cogs and wheels.

A computer gallery displays the latest CD-Roms about space and astronomy with a background soundtrack of David Bowie’s “Star man”.

The giant telescope hasn’t been used since 1975, when the expanding city’s light pollution made it impossible to see the stars clearly. Now the Observatory is purely a visitor centre, welcoming at least five schools a week in the summer.

The Observatory provides worksheets, compiled by the staff with guidance from schools. These guide the pupils through the first exhibition space: the Discovery Zone. The light, bright room is full of hands-on appeal. There is plenty to touch, twiddle and look through as children are asked to think about light. The pupils shine beams through lenses and prisms to reveal that white light is made up of all the colours of the rainbow.

“What is the biggest source of white light you can think of?’’ asks Ian. Lots of hands shoot up. “The sun’’ is the correct answer. From there we establish that the sun is a star, that observatories look at the stars, and that the sun is not actually the biggest star known, just the closest one to us.

The Discovery Zone leads to a larger exhibition room called Reaching for the Stars. This has a more static display of information on the history and work of the Observatory and is aimed at older primary and secondary students.

There is a hushed chorus of “Wow!” as we enter the dark domed room at the top of the tower. The grey, functional circular room resembles the inside of an early aerodrome hangar. In the centre is a huge 36-inch telescope.

The roof of the dome is opened by nothing more high-tech than a rope pulley, which two of the girls are allowed to tug. Once we are looking up to the sky, the dome starts to rotate. Clanking metal wheels on ratchets, heavily oiled and running smoothly, circumnavigate the room. The pupils sit rapt as Ian explains how the telescope works.

One pupil gets a closer view than most. Scott Rollo looks only slightly unnerved as he is strapped into the black metal astronomer’s chair and cranked high into the dome, where the staff once sat and looked at the stars.

“At this age they are really enthusiastic,” says teacher Muriel Keane. “They are particularly motivated by finding things out for themselves.”

The rooftop Computer Gallery is a large space filled with high-tech appeal and more wow-factor relics of the space age. There is the tip of an Australian rocket, still intact after falling to earth.

Mrs Keane is delighted with the school’s day out. “I thought it was excellent, really well presented and with plenty to keep the children’s interest. They thoroughly enjoyed it.”

For Ian Mulvany, taking school pupils around the Observatory is always a challenge. “The younger pupils are always so interested, you have to concentrate to keep up with them. My favourite question was being asked, ‘If stars are so far away, how can we see them?’ I wittered for a whole 10 minutes on that one, finally saying there was nothing to get in the way.”

The Royal Observatory Visitor Centre, Blackford Hill, Edinburgh is open Mondays-Saturdays 10am-5pm, Sundays noon-5pm. Group visits Pounds 2 per child; one adult free per 10 children. Contact education officer Carolyn Chinn, tel: 0131 668 8405. The gallery houses temporary exhibitions by SchoolWorks, part of the educational charity Science Projects