Melbourne Henge February 7, 2024

The Autumn equinox this year is on March 20th, where the Sun rises due east and sets due west and day and night are equal length.

Aside from marking the transition from summer to winter, this is an opportuity to see some "City Henges".

Unlike the famous Stonehenge, whose stones are aligned to catch the summer and winter solstices. City henges are found in cities with a regular grid of east-west streets, where the rising and setting sun can shine through these human-made canyons at various times of the year. The most famous is Manhattan henge, where the skyscrapers of New York provide dramatic chasms for the setting sun to illuminate.

Less well known but still dramatic is Melbourne Henge.  Where great views are to be had down Collins Street and Bourke street amongst others as the setting sun washes the streets in golden glow.

Did I say east-west? while our CBD streets are nominally east west, they are in fact slightly out of alignment with true east.

The streets of Melbourne are even more out of true being angled at 250 degrees west, which is why the dates for Melbourne Henge for the setting sun is 7 February and 4 November, not on the days of the equinox.

The 'Henge' occurs twice a year when the sun sets perfectly aligned looking down Bourke St from the steps of Parliament house at sunset.  The Sunset is at 8:28 pm. But the henge phenomenon should be visible along the Hoddle Grid at around 8:20 pm.

 And the  phenomenon can be seen in Adelaide too. We lack the skyscraper canyons, but our CBD east-west streets can still be illuminated with a golden glow.

As Adelaide streets are closer to East-west (North terrace being 87 degrees east and 263 degrees west as measured by my trusty compass) Adelaide henge is closer to the equinox. Our best time This is on the 16th at 19:33, when the sun is setting at 263 degrees. However, the sun moves slowly from this ideal alignment and our streets are broad, so good sunsets almost aligned with the streets such as North terrace, Rundle Mall and Hindle  street should be available over a few days.

In contrast, best theoretical sunrise is not until 28 March, when the sun is 87 degrees from East and rising at 7:25. However, to the east is the Adelaide hills, and by the time the sun rises above then it will have moved off the direct line. Ironically the best time for the sunrise to shine down the street is on the 21st, at 7:36, as the sun just clears the Adelaide hills.

Again, those are the best  times, but a few days either side of those it will still be good. So get up early or stay in the city for sunset, and you might see something wonderful.