Building a 76 mm reflector in two Sundays

Our build-a-telescope workshop runs over two Sundays at the Jayanagar centre, and every child goes home with a working 76 mm reflector they made themselves. Here is what happens.

The first Sunday begins with light. Children learn how a curved mirror collects light and brings it to a focus, using a torch, a shaving mirror and a sheet of paper. Then they receive their kit: a 76 mm primary mirror, a small flat secondary mirror, a cardboard and PVC tube, an eyepiece holder, two eyepieces and parts for a simple wooden base. They measure and cut the tube to length, mark where the focuser goes and drill the holes with mentors guiding the drill.

The mirror cell, which holds the main mirror at the back of the tube, takes most of the afternoon. Children learn to handle the mirror only by its edges and why a fingerprint on it matters. By 5 pm, most tubes have both mirrors installed. The second Sunday is for the mount and alignment. Each child assembles a small rocker-box base that lets the telescope swing up, down and around. Then comes collimation, the careful adjustment of both mirrors so they line up exactly. It is fiddly, and children who master it understand their telescope far better than anyone who bought one.

As the sun sets, everyone carries their telescope to the rooftop and points it at the Moon. The first sight of craters through an instrument you built yourself is the moment we run this workshop for. The fee of ₹6,900 includes the full kit and both days.