The Galileoscope™
Tripod not included

In the year 1609, Galileo Galilei became the first person to turn the newly invented telescope towards the heavens. In honor of that auspicious event, 2009 has been designated the International Year of Astronomy.

The Galileoscope™ is a small telescope shipped as an assembly kit specifically developed for outreach activities in the International Year of Astronomy 2009. It is so designed as to offer children and adults all over the world an affordable, high quality telescope that resembles Galileo Galilei's first telescope. However, Galileo's telescope was made of crude optical glass, while the modern Galileoscope comes with an achromatic lens which nearly eliminates chromatic abberration (false colors).

As a cornerstone project for the IYA 2009, the Galileoscope is sold online without any profit, namely for just 15 US dollars (plus shipping)!

When purchasing your Galileoscope, you will be encouraged to donate Galileoscopes to those who could never afford buying one. The primary objective of this project is to get as many telescopes into the hands of as many people as possible -- all around the planet. Everybody should be given a chance to experience the wonder felt by Galileo Galilei 400 years ago.

Make sure to visit the official Galileoscope website:

Robert Brenner
Chinen, Okinawa, June 20, 2009

The Galileoscope is NOT a solar telescope. NEVER point it or any other equipment at the Sun! Instant blindness is the most probable consequence.

Optical construction:refracting telescope
Objective lens diameter50mm
Focal length:500mm (f10)
Eyepiece focal length20mm
Magnification25x (50x with 2x barlow)
True field of view1.5° (0.75° with barlow)
Eyepiece eye relief16mm (22mm with barlow)
Exit Pupil2.0mm
Field Stop13mm
Star transit time360sec (0° decl, 20mm eyepiece)
Maximum magnificationca. 80x (6mm eyepiece)
Minimum magnificationca. 15x (30mm eyepiece)
Prime focus magnification12x
Light gathering area196cm²
Light gathering power51x (vs 7mm eye pupil)
Angular resolution*2.3"
Limiting star magnitude*11.0
Smallest visible Moon features*>15km

* approximate and purely theoretical for ideal observation conditions, which is normally not the case.

What you get for 15 dollars is out of this world. A refracting telescope with a 50mm (2-inch) achromatic glass objective lens of 500mm focal length, one 20mm eyepiece which delivers a power of 25x, plus a 2x Barlow lens which boosts magnification up to 50x using the included 20mm eyepiece. Interestingly, the Barlow can alternatively be assembled as a <0.5° narrow-field 17x 'Galilean' eyepiece to better simulate the optical limitations of Galileo's first telescope.

The 20mm Plössl-like eyepiece offers a long eye relief which is comfortable for eyeglass wearers. The optical tube attaches to a standard photo tripod. What truly amazes is the standard 1.25-inch eyepiece barrel which accepts any optical accessories designed for this diameter. In other words, you can insert your own favorite eyepiece or webcam. The kit consists of snapable plastic parts and can therefore be assembled in 5 minutes or less without need for tools, glue or tape. All specifications at a glance:

With the Galileoscope you can observe the Moon, the bright planets (the phases of Venus, the moons of Jupiter and the ring of Saturn), bright deep sky objects (such as the Great Orion Nebula, Andromeda Galaxy, The Pleiades, M13, M4, etc.), plus so many more stars than can not be seen with the unaided eye.

If you are not satisfied with the supplied plastic lens eyepiece and Barlow (no more can be expected for 15 dollars) you can insert any 1.25 inch barrel eyepiece from your existing collection. The most compact solution would be a zoom eyepiece, such as the common 8 - 24mm design, although we are then talking about a quite different cost level. You may also desire a star diagonal when pointing the scope to objects in high altitude. Note, however, that the light optical plastic tube maybe poorly balanced on the tripod when using heavy eyepieces and diagonals.

Inherent to refracting telescopes, the view through the eyepiece is 180° right rotated, or upside down, but this is of no importance to astronomical observation considering that there is no up and down in space. The included eyepiece offers a wide field of view which spans three times the full moon. The Pleiades star cluster fits nicely into this field. When using the included Barlow, the field is halved though still encompassing the full moon.

Simulated Moon with barlow (50x)Simulated Pleiades in the eyepiece (25x)

Although there is not much assembly fun involved, the Galileoscope is a wonderful first-scope for young children to experience how simple optics perform on the Moon and the bright planets. Like Galileo Galilei, children will be fascinated at seeing that the band of the Milky Way consists of thousands of stars (under dark skies).

Too bad, that it won't ship timely for Father's Day 2009!

Since as of June 2009, the Galileoscope is not yet being shipped, I have used a similar scope kit, Spica, to capture the Moon with a Logitech QuickCam 3000 Pro webcam in prime focus (no filters attached) on May 3rd, 2009 - 11:24 GMT in Okinawa. The image is a composite of two single frames, the upper and the lower limb of the Moon stitched together with unsharp mask applied. It spans over a width of 30.3 minutes of arc, or about the diameter of the full moon. This color image shows an absence of chromatic abberration. The principle optical difference between the Galileoscope and Spica is aperture, Galileoscope 50mm, Spica 40mm. Both come with an achromatic primary lens. Due to the Galileoscope's larger aperture you may expect a slightly better image quality and resolution.