zondag 21 april 2013

Reducing uncertainty: Jupiter really has four big moons, I just wasn't sure

This week I had to defend science a lot (which means I was a lot on facebook and twitter, following discussions between religious people, scientists and people that just like to shout things). I noticed that the definition of science is unclear, not well understood and just disregarded in internet discussions. I know that you cannot be right on the internet (You will miss a good night sleep, next to a gorgeous lady (xkcd)), but I can try ;). There are many definitions of science but I like the following one:

"Science has the purpose to reduce uncertainty with use of observation and discussion"

It clearly states that science does not (really not, so please keep this in mind) have absolute answers to all the questions in life, but tries to keep us busy (with a lot of discussion) by reducing the uncertainty in the answers. It says don't panic, just look around and enjoy. Observations play a primarily and important role in this process. My link to the rest of the blogpost (I got some feedback of a dear friend, who is reading this blog, saying that I jump from subject to subject without clear preparation for the reader. I think it just keeps you focused :)).

A historic observation which changed mankind's view of the world, also changed me in some sense. It happened on a late summers evening. I visited my parents house in Renesse (known by Dutch youth for its interesting summer holiday parties, but known by astronomers for the clearest sky in whole of the Netherlands). My dad and I were enjoying some good whisky that evening. We were gazing at the sky,  the moon was very visible making the scene fantastic (or maybe the whisky, lets just say we had some good discussions). During that summer also the planet Jupiter was clearly visible in the night sky. Being a little bit intoxicated by a very good 'tasters choice' edition of a 16 year old Lagavullin whisky, we decided to make pictures of Jupiter, hoping to catch a glimpse of its moons (who are not visible with the naked eye, even if you squint your eyes and put your hands like a binocular).

Our theory was to use a long shutter time and a fully deployed (zoomed in) camera lens to catch a few photons reflected of the surface of the four Jovian moons. Making an engineering-based camera holder (in other words, study books and the camera strapped together with a lot of duck tape), such that the camera was immovable and pointing towards the largest planet of our solar system. We totally forgot that in those few seconds (shutter time), the Earth moved a little bit, making Jupiter and its moons, seen as five parallel white lines in the night's sky. But we did not give up and experimented for a few minutes when suddenly we saw the same figure as Galilei Galileo did (and Simon Marius, but he was three days to late, see previous blog), changing our perspective of our view of mankind. For me it was the beginning (well sort of, one of the several beginnings) of my scientific mindset.

This picture was taken on 21 august 2010 23:51:27 (Amsterdam time). In a backyard of a house in Renesse, Schouwen Duiveland, Zeeland (So you can figure out which dot belongs to which moon, ephemeris data can be found here).

The camera we used was a simple Canon EOS 350D Digital, with a 70.0-300.0 mm lens. For this observation, we used the following set-up of the camera: Iso 800, 300.0 mm lens, F 5.6 and a shutter time of 1/3 second. This also solved the movement of Earth (the Earth doesn't move a lot in a blink of an eye), resulting in round (non striped) dots being Jupiter and its four large moons.

1 opmerking:

  1. We were quite surprised that with a shorter shutter time and a somewhat normal setup of the camera we got this result.

    It's an example of good space engineering: "to boldly go .... "