A tilted perspective

The Bad Astronomer (and Dave P) both mention a website that claims that the Earth has changed its tilt. This claim is wrong and anybody can easily prove this for themselves.

Most nine year olds in the UK could probably tell you that the Earth spins and the axis of that spin is tilted by about 23.5 degrees. They should also know that that tilt causes the seasons. This is correct and you can check it for yourself by playing around with a torch (the Sun) and something round like an apple or orange (the Earth) or go look it up in pretty much any basic astronomy book. The rotation of the Earth causes the Sun, planets and stars to appear to rise in the east and set in the west. Check this yourself by going outside on a clear evening at sunset.

The website claims that the tilt has increased by another 26 degrees. Let's assume that this had happened (let's not worry about the sheer impracticality of this happening for now) and try to work out how we could test this hypothesis. Well, there are two ways a tilt could be applied and the website is unclear on which they mean. Firstly, the whole Earth could tilt by 26 degrees. If that was the case, the north star - the star that is over the north pole - would no longer be above the north pole. It would now be 26 degrees away from it. That is quite a long way and would be very noticeable in star trail photographs. Try this for yourself; go outside on the next clear night, locate the north star and then just watch it for a couple of hours. I checked it on Friday and Saturday night at it was in the same place as normal for where I live.

OK, perhaps the website isn't referring to the whole Earth tilting. Perhaps the surface of the Earth has just "slipped" relative to the rotation axis of the planet. If that was the case, what would the effect be? Well, that would mean that pretty much every point on Earth was at quite a different latitude to what we would expect. That would then mean huge changes in daylight, sunset and sunrise times for all of us. As the Bad Astronomer rightly points out, parts of Europe would be above the arctic circle and so should be experiencing very little daylight at all as it is winter. However, the sun seems to be rising and setting at times I would expect for this time of year so that rules out that kind of tilt.

Both these possibilities have observable predictions. These predictions do not require multi-million dollar equipment to test though; you can go outside with a bit of paper, a pen and a watch and disprove them within a few hours. Given how easy it is to show these predictions do not match with the real world, I can only assume that the website is some kind of spoof. Unfortunately, not everyone is as clever as a nine year old (nine year olds are pretty smart I'll have you know) so I suspect that this will be spread as "true" amongst adults who are not smart enough to think for themselves.

Posted in astro blog by Stuart on Thursday 11th Oct 2007 (14:52 BST) | Permalink
[an error occurred while processing this directive]
[an error occurred while processing this directive]