Friday, 19 August 2011

Photos examined by astromers, and the core of the planet isn't iron

Well, the photos have been developed and most of them were quite good. Turns out Tom is fairly handy with a camera. Frank has sent the pictures off to an astronomer friend of his, and we hope to have some kind of estimate of the planet's location soon. Most of the pictures looked very much as we expected (see the adjacent picture from an amateur photo site). The only thing Frank has been able to determine from them so far is the rotation of the planet. Doing a calculation using the length of the star streaks and knowing the shutter speed, Frank says that a 'day' on the planet is a bit less than 32 hours. Much longer than here on Earth, but Tom says that it doesn't feel longer; he just has more time to get things done.

The fact that a 'day' is longer there can be the result of a couple different things. Either the planet actually rotates slower, or it has a much larger diameter. A larger planet should have a stronger gravitational field, but only if the composition is similar to Earth's. From the lack of magnetism over there, Frank has hypothesised that the planet is lacking the iron core that forms the basis of Earth's magnetic field, so although it might be larger, it has less mass. In other words, it is less dense.

So, based on his guess about the core, Frank's next experiment is going to test the exact gravity there, using a Kater's Pendulum. I suggested that he also measure the size of the planet the same way Eratosthenes did, but he just laughed. Apparently we'd have to explore a bit more of the planet to be able to get measurements like that.

BTW we can't just keep calling it 'the planet', so Frank thinks we should name it, but I'm certain that the natives already have a name for it. We just need to ask them. What do you think? Let us know in the survey.

I'll report on it next week.

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