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Sunsets are moving north

Here’s what happens if you take a photo of the sun each day at sunset, for several days in a row. You can see the sun’s northward motion along your horizon.

Photos taken in March 2015 by Abhijit Juvekar in Dombai, India.

Photos taken in March 2015 by Abhijit Juvekar in Dombivli, India, part of the Mumbai metropolitan region.

Abhijit Juvekar posted this photo to EarthSky Facebook yesterday (March 24, 2015), in an illustration of the fact that – at this time of year, as seen from across the globe – the sunsets are moving a little farther northward each evening. For us in the Northern Hemisphere, it means the sun’s is taking a higher and higher path across the sky. We’re feeling the sun’s light and warmth more directly than a few months ago, and the days are getting longer. Meanwhile, in the Southern Hemisphere, the northward-moving path of the sun ensures that winter is coming to that part of the globe. Abhijit wrote:

We all see the daily motion of sun across the sky, indicating the rotation of Earth. However, in order to know the revolution of Earth in orbit around the sun, we can mark/image the sunset/sunrise position with respect to a fixed foreground landscape.

Using same camera setup, just click the images every day or on alternate days, and combine them using a Photoshop layer mask to mark the position of sun’s disc each day with respect to a fixed horizon line.

At this time of year, you will clearly see that the sun is gradually moving towards the north day by day. It continue to move in north until it reaches maximum north on the June solstice, and then start moving backwards and gradually reach to maximum south on the December solstice day.

For observers in Southern hemisphere, the same is true, but the seasons are reversed.

This method is also useful for locating the exact geographical east and west points from a fixed observing site, by noting the respective sunrises and sunsets on the days of equinoxes.

It’s a simple experiment and fun to try even with mobile camera or digicam setup. All you need to do is click the images of Sunset using same focal length on regular interval days.

Read more info here.

The method can also be used to make a solar analemma as mentioned here.

Try it out.

Thank you, Abhijit!

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Bottom line: Abhijit Juvekar in Dombivli, India took a photo of the sun on two days in March, 2015, showing the northward movement of the sunset along the horizon.

Deborah Byrd

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