Saturday, May 26, 2012

Countdown to Transit of Venus

A curious composite image from the TRACE solar observation satellite, watching the planet Mercury move across the sun in 2003.

Parallax shift as recorded by TRACE satellite (orbiting Earth)
 recording the Transit of Mercury 2003.
Image source  
No - Mercury isn't wobbling ... it's the satellite taking the photos that is moving, orbiting Earth on a North-South path. Mercury thus appears to move up or down, depending whether the satellite is North or South of the equator when the image is taken.  While man-made satellites able to photograph Mercury passing the sun are relatively new, people have been measuring the parallax shift during the transit of Venus since 1761 by sending observers to different points across the globe. Australians feel a particular affinity with the Transit of Venus: measuring it was a key motivation for Cook's voyage on the Endeavour.  In two weeks, Venus does it again - the last chance to see it in your lifetime. Australian students and their teachers are particularly fortunate as the ToV event starts and ends with the school day on June 6th.

Looking for activities to do with students? has an impressive one-stop collection of resource links. With so many to choose from, here's a short list we are using in our mathematics faculty to prepare students for watching the event:
  • Two videos we found to be high both engaging and high quality, with mathematical content suitable for all ages:

If you like the idea of using satellite imagery to demonstrate the parallax shift, it's interesting to compare image from TRACE (which does orbit the Earth), to that taken by SOHO (which does not orbit the Earth):

No parallax shift from SOHO images!
Transit of Mercury 2003. Photo: NASA.

Saturday, May 12, 2012

Still alive ...

It's been a long time between posts .. but rest assured I'm still alive - just swamped by teaching right now. Hope to write some more soon on the following topics:
  • Useful metaphors for teaching senior trigonometry
  • Ideas our school is doing for the Transit of Venus 2012 - with some resources
but in the meantime ...

A notice to all new teachers: Get yourself to the doctor ASAP and get vaccinated for whooping cough. Yes - you probably got vaccinated as a child, but immunity only lasts 10 years.   I really really wish someone had told me to do this. Yes - I caught it - most likely from someone at school - I have only just stopped coughing after three months of hacking. And even worse, I could have spread it around. Fortunately my doctor picked it up and gave me the treatment to stop it being infectious. Sadly the treatment doesn't cure the cough - making for a very unpleasant time the last few months. As a new teacher you are particularly vulnerable to catching and spreading the disease. In New South Wales, Australia, there are 20,000 cases diagnosed per year - and probably many many more go undetected - because adults just put up with it. The vaccine is normally combined with a Tetanus booster - just do it!