Weather News

Let there be light

Ben Domensino, Friday September 23, 2016 - 08:42 AEST

Most Australian's slept through the vernal equinox last night.

An equinox refers to the moment our Sun passes directly over Earth's equator, which happens twice each year. In September the vernal equinox, or Australia's spring equinox, witnesses the sun passing into the southern hemisphere.

Think of it as the moment in time our northern hemisphere neighbours handball us the sun, bringing them into autumn as we move through spring.

From now until late December, the sun will keep travelling south relative to Earth's surface, causing it to get progressively higher in Australia's sky. As a result, temperatures will climb and days will become longer in length.

Another way to think of the solstice is the date when day and night are roughly equal in length. In reality though, days are already longer than nights in Australia. Here's why: The centre-point of the sun rises and sets approximately 12 hours apart on the day of the equinox (today). However, at sunrise we see the top half sun peek above the horizon before its centre-point comes into view. Just before sunset, we also see the top of the sun for a few minutes after its centre-point has dropped out of sight. Thanks to these brief half-sun glimpses at either end of the day, the length of daylight in Australia is already 7-10 minutes longer than night on the vernal, or spring equinox.

Celestial mechanics can be difficult to grasp, so if you've had enough for today, take a break and go outside to enjoy the longest day since March.

- Weatherzone

© Weatherzone 2016

Enter a postcode or town name for local weather, or text to search the site. » advanced search

Weather News

» all stories

A very wet weekend for southeast Qld, northeast NSW

11:48 AEST A prolonged rainfall event is set to bring large totals to parts of NSW and Qld from Saturday, with possible heavy falls and flooding. A low-pressure system in the Coral Sea, a deepening coastal trough and persistent easterlies will bring moisture-laden air into southeast Qld and northeast NSW will bring days of rainfall to the region. While there is not a drop of rain on the radar over southeast Qld and Northeast NSW on Friday morning, the mass of cloud associated with a low in the Coral Sea will enhance rainfall over the weekend.