Radmila Topalovic
Spring is a time for new life, new starts and rebirth, some of us will spring clean our homes and lives, ready for the summer. Animals that hibernate such as bats and bears wake up in March and April, when food is more plentiful. Many animals undertake arduous migratory journeys in the spring. Some Monarch butterflies migrate 1900 miles from the forests of central Mexico to the U.S. and Canada and grey whales swim more than 5000 miles along the Pacific Coast from Mexico to the Arctic seas in late-March and April.
The Romans 2800 years ago started their 10-month calendar in spring, they designated 1st March as the start of the New Year. This changed to 1st January in 45 BC under Julius Caesar. In England, from 1155 to 1752 New Year’s Day was 25th March. It was changed to 1st January when the Gregorian calendar was adopted. The Babylonians (1890-539 BC) used a hybrid lunisolar calendar, New Year began on the day of the first visible waxing crescent Moon after the vernal (spring) equinox.
Since the winter solstice on 21st December last year, the period of daylight we experience in the northern hemisphere is gradually getting longer. The earlier sunrises and later sunsets remind us we are on our way to summer, when we will enjoy our longest and sunniest days and shortest nights around the summer solstice (or midsummer’s day) on 21st June. Mid-way between these two points in the astronomical calendar is the vernal equinox, when sunrise and sunset are 12 hours apart. This day of equal daylight and night-time takes place on Thursday 20th March at 9:01 GMT this year.
Our planet is tilted relative to the flat disc of our solar system, as shown in figure 1. As the Earth orbits the Sun it can be tilted towards or away from the Sun; at the vernal and autumnal equinoxes it is neither. At the winter solstice observers in the northern hemisphere are tilted away from the Sun, we experience cooler weather and shorter days and the Sun is relatively low in the sky. Observers in the southern hemisphere have their midsummer at this time. At the vernal equinox the Sun crosses from the southern to the northern hemisphere and climbs continuously northwards as we approach the summer solstice, brightening and warming our skies. Meanwhile, observers in the southern hemisphere enter midwinter. British Summer Time (BST) or Daylight Saving Time (DST) starts on Sunday 30th March 2025, clocks go forward one hour at 01:00 GMT and we enjoy an extra hour of daylight in our evenings.
Figure 1: The Earth in orbit around the Sun
There is plenty to see in the night sky this month. Shortly after sunset four planets are visible to the naked eye. Look towards the west in the direction of the sunset, dazzling Venus is prominent at dusk, Mercury sits lower in the western sky. To the far left of Venus Jupiter can be easily seen high in the south, Mars with its reddish glow is positioned east (further left) of the gas giant. Sirius, the dog star and the brightest star in the night sky, forms a lower apex of a triangle with Jupiter and Mars in the south-east. Binoculars may reveal the four largest moons of Jupiter and you will see the heavily cratered surface of the Moon, the crater walls stand out beautifully during the crescent and quarter phases. You can download a stargazing app on your mobile phone to help you navigate the night sky.
Figure 2: The sky on 3rd March at 18:20 GMT. Venus and Mercury low in the west, Jupiter and Mars high in the south, waxing crescent Moon also visible. Taken from Stellarium (astronomy/planetarium software – www.stellarium.org).
About the author
This blog was written by Radmila Topalovic, astronomer and co-author of Night Sky Almanac 2025. Never miss a night sky event wherever you are in the world with this beautiful month-by-month guide to the night sky.