Sticky Post

We are currently not maintaining our blog here. Please go to our Facebook Page for latest updates!

Monday, June 4, 2012

Preparations for Transit of Venus Part 3 - Telescope Viewing

Previously, I shared about the various filters and projection techniques that can be used to view the Sun, however, through the course of our preparations I've often forgotten how small Venus is going to be compared to the Sun.
Its easy to get caught up in the hype about an event that won't happen again for another 105.5 years. Some of us here, have nicknamed this event "the little black dot", as this is just what we are expected to see, a tiny black dot. Recently I read some articles that say Venus will be so tiny, it will be hard to spot using just a solar filter alone, like the ones I shared in Part 1 of the series of posts.

In light of that, its probably best to use a more magnified view like telescope or binocular projection (see Part 2). Even better, would be direct viewing through a telescope which should ONLY be attempted with the aid of suitable TELESCOPE SOLAR FILTERS. Which is exactly what we'll be using for our transit event.

Here's one of our telescope filters in action last week:

The filters are almost like mirrors, reflecting most of the light, so that only a tiny amount of light from the Sun is allowed to enter the telescope. There will be quite a number of these telescopes set up around the observatory grass area by ourselves (scobbers), TASOS (The astronomical Society of Singapore) and Aljunied Astronomy Club for visitors to look through.

We will not be opening our main observatory telescope as the telescope will be too high for some (e.g. children) to reach safely due the position of the Sun. We also found that in large scale events the narrow staircase becomes too congested, such as in this photo from our 2009 solar eclipse event:
Instead, I'll be connecting a video camera to the main telescope to provide a live video feed of the event that can be shown on a TV below, near the queue line, so that visitors can get to see the transit whilst their standing in line.
Above is a photo of a solar filter attached to the guide scope on the main observatory's telescope. As you can see its just like a mirror and I can also see that I need a haircut.
During testing I took some photo of the Sun through this telescope (and filter) with my phone and got some rather nice images:

This is similar to what visitors through the telescopes on Wednesday. The top image shows some cloud moving in front of the Sun. The second one shows some faint sunspots in the centre of the Sun, caused by magnetic storms, which are often the source of solar flares.
Later I attached a DSLR camera directly to the telescope for a closer look at the sunspot:

Amongst the sunspots there were quite alot of other black dots and specks. Which turned out to be bits of dust and other marks on the lens. Despite, cleaning the accessible parts of the lens some of the marks remained. I guess when a telescope is more than 20 years old and in use every week, its bound to pick up these kind of marks. Perhaps its also time for a full service.

In addition to the telescopes we'll also have a number of solar projection boxes called Venuscopes that can display a large reflection of the Sun and hopefully Venus as well.

The transit of Venus may only be a little black dot, but its not every day that we get to observe something moving in front of the Sun, and its something that telescopes all over the world will be trying to view. In addition to Science Centre's event there will also be telescopes set up at NUS, Galaxy CC and few other places in Singapore to witness this rare event.

Finally, if the weather is cloudy or you don't want to be standing in line, the transit can also be viewed online or even from space. NASA's SOHO satellites has various solar cameras that will witness the event. The website currently shows images of Venus approaching closer to the Sun over the next few days:

Also some overseas observatories will be screening live webcasts of the event such as ExploratoriumSlooh.comBareket Observatory (Israel) and Astronomers without borders. Happy transit watching!

No comments:

Post a Comment