by Samir Dhurde

As a subject that acquaints us with the vast universe and our place in it, any mention of Astronomy draws the attention of many. It is also good to attract students towards Science and hence is a very useful tool for teachers.

Yet, as something to practice for oneself, hardly anything beyond watching the moon and stars can be done without needing a telescope. This is a hurdle that Astronomy communicators and teachers come across when they want to share all these objects and beautiful sights that they talk about in their presentations etc. These optics and other resources are often costly and not easy to come by.

Many colleges too have started courses in Astronomy connected to a Physics syllabus. The instruments bought for the practical sessions are however seldom used due to their high cost and a demand for time consuming maintenance. This is a serious problem that can be addressed by the availability of cheaper, DIY alternatives that people could relate to. With these people could also concentrate more on the observations and the Science rather than whether they are going to break the instrument.

One case to mention, in the perspective of India, is a small DIY telescope. There a many examples available to buy as kits, like the wonderful Galileoscope. Built on the same idea (and hence a similar name – (Galileoscope++), it however aimed to get people to know how to make a telescope in a programme carried out India by the Inter-University Centre for Astronomy & Astrophysics(IUCAA) and many associated Universities. This is a telescope made using a 2 inch achromat objective lens, an eyepiece and a lot of small parts that are sourced from the local plumbing raw materials supplier. Each part in this, that can be “broken” (except the lenses, which people have to learn to respect anyway), is easily replaceable, even by a child! These cost ~ US$ 45, with the lens covering ¾ of the cost and made locally in India too. The two plus-points are that it uses an achromatic lens and that at this cost it also includes an Alt-Az mount!


Gplus telescope sunimage
G++ telescope Sun image

The success of this telescope lies in the fact that hundreds have been made and used by urban and rural schools, astronomy clubs as well as individuals. The teachers have given them to students to take home and to return them the next day, resulting in many confidence building, ‘original’ observations. It has also been modified for university teachers and outreach. It can be turned into a very safe Solar viewer. It has also been used for sun related college level experiments, eg. the study of Limb Darkening, by adding a light-dependent resistor (LDR, also called a photocell).

A few more examples of low cost tools for Astronomy, developed and used over many years are listed as below. They had been developed under the creative purview of Arvind Paranjpye, previously the in-charge of the public outreach programme of IUCAA and presently the Director of Nehru Planetarium, Mumbai.

CD Spectroscopes: A good use of modern trash like used CDs and DVDs, this is a great tool to study very good quality spectra of any light source. These can be made out of a piece of CD and a cardboard box. The only expertise needed is to know what angle to keep the light source and the CD, which causes the diffraction.

CD spectroscope closeup
CD Spectroscope close-up

CD spectroscope using
Students using a spectroscope

Coelostat:  A device to steadily track the slowly moving Sun in the sky and direct its light to a single point through the daytime. This can be used for anything from making a constant light source inside a classroom to study the spectrum of the Sun. All it needs is a motor tweaked to a speed of one rotation per day, and some knowledge of positional Astronomy to calculate some angles.

safe solar viewSafe solar-viewing

safe solar viewing

Night-sky Photometer:  This is a very low cost photometer that came out as a by-product of the research at the IUCAA instrumentation lab. Again, using a photosensitive diode or LDR and a predesigned circuit, it can be built by teachers or students themselves as a project. It can be used along with the above telescope too! The use can range from giving kids a feel for how measurements are important in Science, to studies of atmospheric extinction data from which is useful even for Astronomical observatories.

teachers making photometer
Teachers making photometer

In places where computers are available, all these tools can be combined with free software like SalsaJ  to be used as the stepping stone for knowing what professional Astronomy is like.

These are only a few ideas bringing the most vital aspects of observational Astronomy within the reach of learners and amateurs. Some of these ideas are not new or indigenous as such but their effectiveness has been well tested in many places in India and various other places in the world, where there is acute lack of resources. Using this post for the Global Astronomy Month, we can make it clear that Astronomy can be done to a considerable level of advancement without needing expensive instruments.

Gplus telescope wkshp group foto
A group of proud students with their freshly made G++ telescopes at one of the many IUCAA sponsored workshops

Educators sometimes also need inexpensive ideas to explain some concepts. We are happy to share some that we have documented here.



blogprofileSamir Dhurde is in-charge of the popular outreach programme - SciPop, of the Inter-University Centre for Astronomy & Astrophysics (IUCAA) in Pune, India. He loves working with children the whole day and is a Radio Astronomer in his free time. His is also actively involved in efforts to make quality outreach an integral part of science institutes’ mandate in India. Being involved in several national campaigns, aimed at taking science to everyone through very simple methods, he loves traveling to reach the remotest people of his vast and beautiful country.


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