2月17日的Astro Sundial应用程序分析

The hour lines from 6 to 18 (hour angle of the Sun) are shown at the bottom: subtracting 12 gives the hours that are missing or have passed since the transit. The virtual stylus is placed perpendicular to the screen, with the smartphone facing south; in dark red is the projection of its shadow whose length depends on the elevation of the Sun above the horizon. The orange circle indicates the length of the shadow when it is equal to that of the stylus. The analemna is shown at the top indicating the discrepancy, in minutes, due to the equation of time, between solar time and local time (not daylight saving time). By touching the screen, a (movable) table is displayed containing a lot of data relating to the position of the Sun and more. The zodiac sign in which the Sun is located is the astronomical one and not the astrological one! Warning: This app works fully only for latitudes between 30 degrees and 70 degrees north. Hourly, solstitial and equinoctial lines are not plotted for these latitudes.