Explore Scientific

Galileoscope Telescope Kit


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The Original Galileoscope, Developed by Leading Astronomers, Optical Designers, and Educators

"I am surprised that my Galileoscope has become my working scope. Yet, I am reminded of what we often hear in the amateur astronomy community - The best telescope is the one you use most." - David O. Treviño, Cloudy Nights

Created as a cornerstone project for the 2009 International Year of Astronomy (IYA), the Galileoscope telescope kit solved a long-standing problem: the lack of a high-quality, low-cost kit suitable for both optics education and celestial observation. The Galileoscope was also a cornerstone project of the 2015 International Year of Light (IYL).

Over the course of the project managed by volunteers and promoted mainly through word-of-mouth, more than a quarter-million Galileoscope kits have been distributed to teachers, students, and other enthusiasts in more than 110 countries for science education and public outreach.  

The program was only expected to last through the IYA, but the global astronomy education and outreach community loved the kit and asked its creators (Stephen M. Pompea, Richard Tresch Fienberg, Douglas N. Arion, Thomas C. Smith, and Douglas Isbell) to keep it in production, and after nearly ten years of serving the educational STEM community that team was preparing to wind down.

But the demand by the educational community has remained strong, and a search ensued to find a worthy successor of the Galileoscope.  Explore Scientific was approached in late 2018 to take over manufacturing and distribution, and we both felt the project was a good fit for Explore Scientific.

Now we can ensure that educators and students around the world can continue the legacy of unlocking the learning process of exploring the universe with telescopes that people assemble themselves with the original Galileoscope Kit!

  • This high-quality telescope kit was developed by leading astronomers, optical engineers, and science educators to showcase how early astronomers made their discoveries.
  • The 50mm diameter telescope offers 25X to 50X magnification.
  • Includes standard components such as a base that fits most tripods (not included) and a 1.25 focuser that accepts a wide variety of optional additional eyepieces
  • Includes everything you need to build your own telescope and eyepieces
Galileoscope design drawing

Galileoscope design drawing. Courtesy Merit Models.

Quick Links:
Optical Design Mechanical Design Focuser
Galilean Eyepiece 2× Barlow Lens Tripod (not included)


The Galileoscope is a refracting telescope, or refractor: a long tube with a big lens (the objective) at the front end and a small lens (the eyepiece) at the back end. The great Italian scientist Galileo’s telescopes were refractors, too, but the Galileoscope improves upon his 400-year-old design in several important ways, as described below.

While assembling the kit, which requires no tools or adhesives, you can learn basic optical concepts, including how lenses form images. With your completed 2-inch-diameter, 25- to 50-power telescope, you can enjoy sharp views of lunar craters and mountains, Jupiter and its moons, and Saturn’s rings. The kit is augmented with free, standards-based optics-education and observing activities, available in multiple languages.

The Galileoscope is suitable for students of all ages from 8 to 88!The Galileoscope comes in a cardboard box measuring 19½ by 6¼ by 4¼ inches (49.5 by 15.9 by 11.1 cm) with a shipping weight of 2.6 lb (1.2 kg). 

Here are the instrument’s key optical characteristics:

Objective diameter: 50 mm (2 inches)
Objective focal length: 500 mm (f/10)
Eyepiece focal length: 20 mm
Magnification: 25x (50x with Barlow)
Field of view: 1½° (¾° with Barlow)
Eyepiece eye relief: 16 mm (22 mm with Barlow)
Eyepiece barrel diameter: 1¼ inches (31¾ mm)


The field of view is the angular diameter of the circle of sky you see when you look into the telescope’s eyepiece. The full Moon is about ½° wide, so the Galileoscope’s field at 25x is three Moons wide.  This is just big enough to encompass the splendid Pleiades star cluster in Taurus, one of the objects Galileo marveled at 400 years ago. If you double the magnification to 50x using the included Barlow lens, the width of the field of view is correspondingly halved.

Barcode: 09830403681