What's in the skies for April 2025 - Venus becomes a Morning Star

Welcome to the highlights of our Southern Skies for April 2025!

It's now well past the autumn equinox in Australia and New Zealand. The Sun is moving into the northern parts of the sky, and the days are getting shorter.

• Venus is in the early morning sky.
• Saturn is now starting to appear in the pre-dawn skies. 
• Jupiter and Mars are still visible just before sunset, although they will gradually sink into the Sun's glare at sunset over the coming weeks. 

1st of April is the traditional April Fool's joke day...although with the world as it is the moment, even the best of them had trouble keeping up with reality!

5th of April is First Quarter Moon.  As always, the Lunar phase we suggest for new telescope users as being the best time to start observing the Moon as the Sun is low in the sky from the Lunar surface and produces dramatic shadows and highlights across the Moon's mountains and craters.

Mars in Gemini

Look outside towards the northwest early in April to spot the unmistakable red glow of the planet Mars nestled in the constellation of Gemini which is also known as "The Twins."

The view from Sydney around 8.00pm in the second week of April 2025

The Twins refer to the brightest stars in Gemini, Castor and Pollux, named after two twins in Greek mythology. These stars form the heads of the twins. The brightest of the two is Pollux, even though the slightly dimmer Castor has the label of "Alpha" in the constellation which is normally reserved for the numero uno in terms of how bright a star is. This due to a measurement error back in the day when stars catalogues were being drawn up. Despite being called the twins, the two stars are very different. Castor is actually a six-star system some 52 light years away. It's quite a fascinating and complex collection of binary stars. Orange coloured Pollux is a giant star, 34 light years away. Despite them appearing close to each other in the sky, the "twins" are actually only close due to their line of sight view from Earth. 

13th of April - Full Moon.

The entire Lunar surface that faces Earth is in full daylight and brightly lit.  Did you know that the Moon reflects back into space just 12% of the light it receives from the Sun? In other words, its "Albedo" is 0.12.  This explains why Moon rocks brought back to Earth by Apollo missions are so dark, yet the Full Moon appears so bright. If the Moon had the same Albedo as the clouds around Venus - 0.7 - it would several times brighter.

20th of April - An Easter treat: a planetary nebula.

Hopefully the Easter Bunny will have delivered the goods and you'll be relaxing over the long weekend. 

Where to find the planetary nebula, NCG 3132 around 9.30pm on Easter Sunday in the southwestern sky as seen from Sydney

High up in the sky is a planetary nebula called NGC 3132, known as the "Southern Ring Nebula" or the "Eight-Burst" Nebula.  A planetary nebula is the shell of gas ejected by large, red giant stars towards the end of their lives. Star like these around one to eight times the mass of the Sun, with larger stars producing supernova. They're not planets at all - they appear like faint ghosts of the large Solar System planets and were called this by early telescopic astronomers. 

You'll be able to spot NGC 3132 even in a small telescope. Stepping up to a 6" or 8" Dobsonian will reveal more details. 

21st of April is Third Quarter Moon. 

Like the first quarter, a perfect time for Lunar observations with the Sun in the sky on the Moon's surface producing dramatic shadows that highlight features. 

The Southern Cross high in the sky - great viewing for binoculars

At little bit later in April and a few hours after dark, the famous constellation of the Southern Cross or Crux is riding high in our Australian skies.

The view south around 10.30pm Sydney time on the 21st of April 2025

Nearby are the familiar two bright pointers to the constellation of Southern Cross or "Crux". If you head out before the Moon rises a bit after 11.30pm, you'll discover it's an ideal time to explore the dense star clouds of the Milky Way as they run through this part of the sky and into the nearby constellation of Carina. There's large collection of deep-space objects within our home galaxy that are easily spotted even with a small telescope, but don't forget just about any pair of binoculars will also worth using on this part of the sky.

Both of two Magellanic Clouds can be seen and appear like a detached parts of the Milky Way and are also worth spending time on.  They're galaxies, home to billions of stars and large regions of star formation. We'll be talking about galaxies in an upcoming blog entry.

25th of April - pre-dawn Solar System treat.

If you're rising early to attend ANZAC Day Services you'll be greeted by a wonderful alignment of the crescent Moon, Saturn, Venus and even Mercury- all shining brightly in the pre-dawn sky. 

The orbit of Venus has taken it away from the sky near the setting Sun and is now a bright "morning star" - after the Sun and Moon it's the brightest object in the sky. 

The Moon, Venus, Saturn and Mercury on the 25th of April around 5.30am as seen from Sydney

It will also be an opportunity to spot the Solar System's innermost planet, Mercury. The small rocky world is often hard to observe due to its closeness to the Sun and can only be low spotted in the pre-dawn or dusk skies.

27th of April - New Moon

There's no Moon visible in the night sky: the perfect time for deep-sky observing or astrophotography. 

Cheers,

Earl White 

BINTEL

4th April 2025