Transit of Venus with Joel Tan

The most recent transit took place last Wednesday on 6 June 2012.

After attending an optics-related sabbatical in Term 1 2012, one of our Secondary 4 students, Joel Tan, was inspired to use this new knowledge to design a device which could be used to view the transit of Venus across the Sun. The idea was to allow the observer to aim at the Sun as if looking directly at it, but with reduced intensity. As of now, we call the device the 'Solar Scope'.

Though the Solar Scope had not worked as well as Joel had expected on the day of the transit (he could not see Venus through his device ):), he is not discouraged! He is continuing his work to improve on the device in hope of being able to see sunspots in the future. Joel is also extremely fortunate to have advice from Mr Ronian Siew and Mr Tan Peng Kian along his 'Solar Scope' journey.

We are working on some videos on Joel's experimentations with his Solar Scope. Stay tuned!

  1. Transit of Venus
  2. Significance of Optics

1. Transit of Venus

A transit of Venus across the Sun takes place when the planet Venus passes directly between the Sun and Earth. During a transit, Venus can be seen from Earth as a small black disk moving across the face of the Sun. The duration of the transit is usually in hours (the transit of 2012 lasted 6 hours and 40 minutes). A transit is similar to a solar eclipse by the Moon.


Transits of Venus are among the rarest of predictable astronomical phenomena. They occur in a pattern that generally repeats every 243 years, with pairs of transits eight years apart separated by long gaps of 121.5 years and 105.5 years. The last transit of Venus, which is also the last of the 21st century, occurred on 5 and 6 June 2012.

If Venus and Earth revolved around the sun on the same plane, there would be five inferior conjunctions – and five transits – of Venus every eight years. However, Venus’ orbital plane is inclined to Earth’s orbital plane by 3.4 degrees. Because the orbital planes of the two planets don’t quite mesh, a combination of factors is necessary for a transit of Venus to take place in Earth’s sky.

external image Transit_diagram_angles.png

Links to more information on Transit of Optics:

2. Staring at the Sun: The Significance of Optics

This is probably one of the most known conventional wisdom:

    • "Don't look at the Sun or you'll go blind."

While many argue over whether sun-gazing can result in complete blindness, it is mostly agreed that staring at the sun may result in some sort of eye damage (medically known as solar retinopathy). The damage is usually photochemical in nature and not due to heat. UV light from the Sun alters the chemistry of the cells of the retina.

So, how do we go about looking at the Sun (and in this case, Venus) without damaging our eyes? This is where optics come into play. Reducing the intensity of light from the Sun using various instruments allow us to stare right at the Sun without causing significant damage to our vision. With this aim in mind, Joel designed and constructed the 'Solar Scope'. The scope is based on the idea that glass windows reflect approximately approximately 4% of light.


3. Hwa Chong High School Open House 2012


4. Viewing the Transit