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How the sunset point moves along the horizon through the year

All year

The spot on the skyline where the sun goes down is not fixed. It slides north through spring and south through autumn, covering about 65 degrees of horizon over a year from this latitude, and it moves fastest around the equinoxes at roughly half a degree a day before slowing to a near stop for two or three weeks around each solstice.

Why this time of year

The weeks either side of an equinox are the fastest the setting point moves all year, so a landmark you pick near an equinox shifts visibly within a week or two. Then watch it grind to a halt as the solstice approaches.

How to notice it

  1. Pick one standing spot with an open view west and use it every time: a doorstep, the end of the driveway, one fence post. The whole thing only works if your feet go in the same place.
  2. Pick one landmark on the far skyline near where the sun goes down. Prefer the farthest one you can see, which removes most of the error from small shifts in where you stand.
  3. Once a week, note how far the setting point sits from that landmark. A strip of tape on a west-facing window works, or a photo from the same spot.
  4. Compare after a month. Near an equinox expect roughly three to four degrees a week, about seven sun-widths. In the three weeks around a solstice expect it to look parked.

Try this with kids: Find the thing on the skyline the sun goes down closest to tonight. Come back in a week, stand in exactly the same footprints, and see which way it moved.

solstice is from the Latin for sun standing still, the day the setting point reaches the end of its range and reverses

Safety

  • Do not stare at the sun, including a low sun that looks dim and orange. This works from the glow where it meets the skyline, using brief glances, or from the bright afterglow once the disk is down.
  • Never point binoculars, a telescope or a camera viewfinder at the sun.
  • Pick a spot away from traffic. West-facing sightlines put the low sun straight into drivers' eyes.

Sources

  • www2.hao.ucar.eduNSF NCAR High Altitude Observatory: the same-location and distant-landmark method, and the solstice standstill quantified at about 10 arcminutes a day twenty days out, 5 arcminutes ten days out and under 1 arcminute in the final three days, against a naked-eye detection limit of at most 4 arcminutes. Its near-30-degrees-either-side figure is computed FOR 36 DEGREES NORTH, which is why this entry does not reuse it directly.
  • earthsky.orgEarthSky, at about 40 degrees north: the sun sets about 7 degrees north of due west 14 days after the March equinox, which is about half a degree, one sun diameter, a day. Also that at mid-northern latitudes there is a two to three week window around the solstice in which you probably will not discern any movement.
  • gss.lawrencehallofscience.orgGlobal Systems Science, Lawrence Hall of Science, UC Berkeley: the equinoxes are the times of maximum rate of change of sunset and sunrise horizon positions, while around the solstices those positions do not change much from day to day.
  • aa.usno.navy.milUS Naval Observatory: the sun's declination runs from +23.4 degrees at the June solstice to -23.4 at the December solstice, passing through zero at the equinoxes. This is the quantity whose rate of change is maximal at the equinoxes and near zero at the solstices.
  • aa.usno.navy.milUS Naval Observatory seasons API, called directly during the refute pass and returning for 2026: September equinox on the 22nd at 21:05 daylight time, December solstice on the 21st at 16:50 standard time.

Checked against these sources on September 6, 2026.

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