Australasian Science: Australia's authority on science since 1938

Skygazing in July

By David Reneke

Your guide to the night sky this month.

There’s a New Moon on July 11 so, for awhile, the skies are going to be nice and dark. Ideal for stargazing! In fact this month is full of stargazing goodies so see you in the backyard right after dinner, OK?

With the glare of moonlight gone so many more stars are visible and the colours stand out nicely as well. Watch for a lot of twinkling stars this month due to unsteady air currents and water vapour in the atmosphere. Add in a bit of wind and you start to get a ‘star’ which can change colour and make people wonder if they are seeing a UFO.

After dominating the morning sky for months, bright white Venus, now the ‘morning star,’ is rising above the Eastern horizon just before twilight. Be quick to catch it.

So, what’s the difference between the morning star and the evening star I hear you ask? Nothing, they’re actually the same thing, namely Venus. The distinction between “morning” and “evening” merely refers to the time at which the planet is visible. Simple isn’t it? And you thought astronomy was hard!

Jupiter is high above the north eastern sky with Mars rising later and much lower down. Saturn is readily visible all night long and almost overhead, high enough for telescopic observation in the early evening. Saturn will be big and beautiful for many weeks to come.

July is the best time to view the Southern Cross. You can always recognize it by the two ‘Pointer’ stars. The bottom one is Alpha Centauri, our closest star, and through a telescope you can see it’s a double star, two stars really close together in the sky. In fact, they are one of the nicest objects to look at through a small telescope.

On July 28, 29 watch for the Southern Delta Aquarids Meteor Shower. You might see about 20 meteors per hour at their peak. Best viewing is usually to the east after midnight from a dark location.

Hey, have you ever wondered, “What are shooting stars?” ‘Shooting stars’ and ‘falling stars’ are both names that people have used for many hundreds of years to describe meteors, intense streaks of light shooting across the night sky.

If you're lucky enough to spot a meteorite (a meteor that makes it all the way to the ground), and see where it hits, it's easy to think you just saw a star “fall.”

David Reneke is a feature writer for major Australian publications including Australasian Science magazine and a science correspondent for ABC and commercial radio. Get David’s free astronomy newsletter at www.davidreneke.com