The Urban Stargazer's Tube: Build Your Own Dark Sky Viewfinder

In our brilliantly lit cities, the glow of light pollution washes out all but the brightest stars, making casual stargazing nearly impossible. This project offers a simple, low-cost solution: the Urban Stargazer's Tube. By creating an isolated, dark viewing chamber that shields your eyes from direct, peripheral light pollution, allowing them to fully adapt to the dark and reveal faint celestial objects normally invisible in the urban sky.

Cardboard

The primary material for the tube structure.

Black Paint (Acrylic)

To create a light-absorbing interior and exterior.

Glue Gun & Glue Sticks

For fast and secure assembly of the tube sections.

Utility Knife

For accurately cutting the cardboard pieces.

Ruler

To ensure straight cuts and for scoring the fold lines.

Cutting Mat

To protect your work surface and provide a measured grid.

Pen/Pencil

For marking measurements.

Eraser (Optional)

To clean up pencil marks.

Paint Brush

To apply the black paint.

Use your ruler and pen to mark the dimensions of the three sections on the cardboard.

The tube will be in the shape of a hexagon (6 sides)

Width (all) = 20cm

Length:

Biggest

1. Piece = 60cm
2. Sides= 10.0cm

Middle

1. Piece = 57.6cm
2. Sides = 9.6cm

Smallest

1. Piece = 55.2cm
2. Sides = 9.2cm

Place the cardboard on the cutting mat. Use the metal ruler as a guide and carefully cut out the three marked rectangles with the utility knife.

Scoring is making a shallow cut (not all the way through) to allow the cardboard to fold cleanly.

Place the ruler along these six marks, press lightly on the blade and cut along the lines, creating a hinge

4. Lay the three scored pieces flat. flip the boards, the unscored side will be the interior. Paint the interior fully with black acrylic paint. (Painting the exterior is optional)

The inner surface must be a deep, non-reflective black to prevent any ambient light that enters from bouncing back into your eye.

5. Once dry, fold each of the three pieces along the scored lines into the hexagonal prism shape.

6. Use the hot glue gun to seal the final long seam on each piece, forming the closed tube. Hold the seam firmly until the glue is cool and set. You now have three separate hexagonal tubes.

7. Finally:

1. Slide the Middle Piece over the smallest piece, aligning the two ends on one side (the viewing end).
2. Slide the Biggest Piece (Outer) over the middle piece, aligning the viewing end.