If I'm entirely honest I don't completely understand how some of these factors combine together into different scenarios. I'm also not showing UTC+08:45/Eucla or Broken Hill because there are limits to how far I'm willing to push my sanity. Nevertheless, please let me know if anything looks wrong. | Guardian graphic Notes and methods It’s already well known that it’s possible to use the angle of shadows to assess the time in an image. SunCalc , a tool which simulates the movement of the sun through the sky on different dates and locations across the Earth, can be used to do this relatively easily. Firstly, here’s what daylight hours look like for each of Australia’s capital cities. This uses the estimated position of the sun at a given time and date, and does not take into account things like the weather. I'm an amateur astronomer, I am trying to find a very accurate terrain profile for my city, useful to input that in an astronomy software and then be able to calculate the times at which the principal stars below the horizon will rise and set. For that reason the following maps compare the amount of daylight hours for each area within a given time period for different situations.

However, sometimes the angle of these shadows might not be clear or there may not be sufficient reference points in a video or picture to accurately judge the angle. The most common argument in favour of daylight saving is how it makes daylight hours more available in the evening, typically after work. Importantly, it’s not necessary to know the actual height of the object casting the shadow. What matters is only the proportional length of the shadow compared to the object. This means that the measurements seen in this article bear no relation to the actual heights and lengths of the objects and shadows. But since we’re only interested in their proportions in comparison to each other, this doesn’t matter. But it’s an interesting topic, and one with no shortage of strongly held views. Some people think it should be abolished, while others advocate for changes like shortening the daylight saving period, or just permanently moving the whole Australian Eastern Standard timezone (AEST) forwards by half an hour, and then removing daylight saving. A contour plot of the hours of daylight as a function of latitude and day of the year, using the most accurate models described in this article. It can be seen that the area of constant day and constant night reach up to the polar circles (here labeled "Anta. c." and "Arct. c."), which is a consequence of the earth's inclination. A plot of hours of daylight as a function of the date for changing latitudes. This plot was created using the simple sunrise equation, approximating the sun as a single point and does not take into account effects caused by the atmosphere or the diameter of the Sun.

But first a disclaimer – working with timezones, daylight saving and dates in general is famously hard in programming. Also, did you know that the timezones database relied on by a huge number of computer systems is maintained by a handful of volunteers? It is! I am using SunCurves to assess the amount of sunlight a parcel of potential agricultural land has. The land has a slight slope and we are unsure if it will receive enough sunlight between April and August to grow crops. We’re not adding any daylight here, we’re just aligning it with the afternoon where you can really appreciate it more,” he said. So with all that in mind I’ve toiled deep into the code mines to produce a series of graphics that use sun position calculations to show how daylight saving currently affects daylight hours in Australia, and what would happen if things changed. But just as the angle of a shadow can be used to work out the angle of the sun from North (the azimuth), so the relative length of a shadow can be used to work the angle of the sun from the horizon (the altitude).

The sunrise equation or sunset equation can be used to derive the time of sunrise or sunset for any solar declination and latitude in terms of local solar time when sunrise and sunset actually occur.

I used Suncurves to create a schedule for myself in 2015. My goal is to wake up "with the sun" each day to get my body’s circadian rhythm synchronized with daylight-based zeitgebers help me get better sleep. Suncurves tells me when the sun will get up tomorrow. So I set myself a bedtime alarm for visible sunrise minus 9 hours to ensure I am getting a solid 8 hours of sleep each night. Suncurves is helping me achieve my health goals!