Why bother with space · 2020 August Star Safari

Instructions to read before looking up – August night sky

About August

The history section features Augustus, the “first citizen” of Rome.

In Ancient Rome, August was synonymous with respected and impressive.

If July is named after Julius Caesar, Roman military genius, August is named after Julius’ Caesar grand-nephew Augustus, who later became his adopted son. He was the first Roman emperor following the Republic, which was destroyed by his great-uncle when he proclaimed himself a dictator.

Augustus called himself the first citizen and the sixth month of the year in the Roman calendar, Sextilis, was named after him. (Britannica). August has 31 days just as July because the Roman Senate decided that both leaders were of equal prestige. The picture on the left is of a statue of Emperor Augustus and the background is made with Starry Night Pro 8 and is the night sky in August.

Julius Cesar and Octavian Augustus are the only two Roman leaders whose names lasted for two thousand years in our calendar.

What’s the Sun up to?

The Sun rises at 7:29 AM on the first of August and earlier and earlier every day so that on the 31st of August it will rise at 6:47 AM and is setting at 5:25PM on 1st of August and later and later 5:55 PM on the 31st of August. The days are getting obviously longer.

In August, the Sun transits first the zodiacal constellations of Cancer, and then moves into Leo on the 11th of August where it stays until September 17th. The zodiacal constellations are those stars visible behind the plane of our solar system, about 8 degrees each side of the ecliptic.

This is why we say they form a band in the sky, called the Zodiacal Band. What’s a constellation?

Since the Sun is transiting both the space we call Cancer and Leo it means we cannot see the stars in these constellations, they are behind the Sun. Need to remind everyone that it’s dangerous to look into the Sun? Of course, if you have solar telescope, that is well maintained and is designed for looking at the Sun, then you can look at the Sun.

The Sun in Leo means only one thing: opposite the Sun (that 180 degrees on the other side of the zodiacal band) is Aquarius. Aquarius will rise just after sunset and be visible all night long.

The Milky Way

The Milky Way is so striking here in New Zealand, that in the absence of a polar star, we believe everyone should find directions by it.

August is another one of those months when you can admire the centre of the Milky Way crossing Zenith at about 8PM. This is quite awesome here which means that if you’re not a late nighter, you can just come straight from work and do astronomy starting at 6PM. That’s fantastic!

When it’s at its highest, the Milky Way stretches here from North to South through Zenith. It’s like a surf of stars on the sky. The top of the wave is the centre of the Galaxy. This is happening right now so you better find yourselves some dark skies and prepare to be amazed!

Here in the southern hemisphere we have such a different perspective, the south celestial pole is leaning towards the centre of our galaxy the Milky Way. We are all used to it being talked about Milky Way as being a river. I am going to challenge that. Here is like the surf of the planetary ocean.

And yes, in the northern hemisphere we can say it looks like a river, the reason being is that in the northern hemisphere Earth’s axis points towards the edge of the galaxy. And the best you can get is a resemblance to a riverbed. Scorpius doesn’t come up more than 30-40 degrees above the horizon so you don’t get to see all that galactic bulge at once. Many ancient references call the Milky Way a river. Latins called it via lacteea – the milky way – literally.

So next time you visit the southern hemisphere or if you are already here take a moment and pay attention to the Milky Way. Follow it south to bump into the Southern Cross – that is in the wake of the Milky Way. Follow it north and you will see Altair and Vega near the horizon, distant harbingers of the North.

Scorpius and Orion

Mortal enemies in ancient Greece, hence they’ve been placed in opposite parts of the sky – or at least that was their mnemonic, Scorpius and Orion look like noting that would indicate they can symbolise a scorpion or a human.

At this time of the year, in Aotearoa, the Māori names for Scorpius is Te Matau A Maui – the fishhook of Maui that drags the Milky Way from the sky all night long.

Orion the hunter is upside down to what you’d be accustomed here at the antipodes and is in the morning sky, you can admire it for a few hours before sunrise.

Bright stars

On the Ecliptic

The ecliptic marks the plane of our solar system bearing the zodiacal constellations. The ecliptic is “a great circle on the celestial sphere representing the Sun’s apparent path during the year, so called because lunar and solar eclipses can only occur when the moon crosses it.

As seen from Wellington the ecliptic runs through the northern part of the sky. In Europe, we see the Sun in the southern part of the sky. That’s why everyone here looks for houses that face north. Very close to the ecliptic are Spica in Virgo, Zubenelgenubi in Libra, Antares in Scorpius and Algedi Prima, Algedi Secunda, Dabih Major and Minor and Deneb Algiedi in Capricorn. The ecliptic intersects the Milky Way in Scorpius and Sagittarius.

Stars in the Milky Way

Starting from the centre of the Galaxy, going North are Shaula, the stinger of Scorpius, Kaus Australis and Nunki in Sagittarius, a beautiful cute star Ionnina in Scutum, then Altair in Aquila and the beautiful open cluster Coathanger in Vulpecula, Albireo and Vega. Unfortunately, the last 3 objects are very close to the horizon, especially in our hilly Wellington and will be very hard to see.

Circumpolar objects to New Zealand

What does that mean?

Circumpolar are objects that rotate around the celestial pole. These objects are above the horizon at all times in a given latitude. For instance the Plough is circumpolar from Britain but here in Wellington we cannot even see it, it’s hidden by the Earth. We could if Earth would have been transparent. Here on the other hand we have the Southern Cross with the pointers that are circumpolar.

The Diamond Cross and the False Cross are circumpolar too. Canopus and Achernar are also circumpolar. The same for the Magellanic Clouds, Omega Centauri, 47 Tucanae, the Jewel Box, the Southern Pleiades, the Gem Cluster and Omicron Velorum. (This one sounds like Emperor Palpatine).

The Southern Cross and the pointers are still in a good position to see. Being circumpolar it means they turn around once every 23 hours and 56 minutes. That’s why they are always somewhere else in the sky. But if you look roughly south, they will be there. Around mid- August after sunset the first of the pointer, Alpha Centauri is at Meridian (Imagine 12 O’clock on an imaginary clock of the sky) and the Southern Cross would be the hand marking 1 o’clock. By 9 o’clock the Southern Cross would be marking 3 o’clock. By the same hour, Canopus will be due exactly south. At 4 degrees altitude, it will be hard to see unless you’ll have a sea open horizon ahead.

In August, these will depend on which day you look and what hour.

Visible objects on the south circumpolar lid (it looks like a giant lid) are 47 Tucanae and the Small Magellanic Cloud, the southern pleiades, Eta carinae, NGC3532,

Other dark patches

The other famous dark patch is the Coalsack, near the Southern Cross. The coalsack is also known as the flounder, which is the Maori name for it. In deed, if you find a truly dark sky, you will see the resemblance.

However, talking about naming objects in the sky, the name of coalsack is also very appropriate as the dark patch, made of interstellar dust matter holds inside it the jewel box, or the Kappa Crucis Cluster, NGC 4755.