Sunrise and sunset

Measured day rise and set times
Measured day rise and set times

So the weekend mini-project was to read out the light sensor (an LDR with a 10k resistor in series) at one of the outdoor wireless thermometers that sends its measurements every so many minutes to the router. And from this we can get the rise and set times which are plotted. The jumps are the transitions from daylight savings time. The other thing you see is that the point of earliest sunset and latest sunrise do not match. This is related to your position on Earth, the orbital parameters of the Earth’s orbit and the obliquity of the rotation axis relative to the ecliptic. In principle you could try to estimate where I live from this data, the times are local, the only thing you need to know is that it is somewhere in our GMT+1 winter timezone. The scatter in the plot is caused by the way sunlight projects into the sensor, the LDR sees the northeasterly skies and during sunset it observes the shadow of the house, while at sunrise there are some trees in the garden.

Last update: 19-4-2015

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