We recently saw the destructive power of hurricanes Milton and Helene, as they cut a path of destruction through various states in the US. They left in their wake flooded businesses, broken roads, power outages, and other problems. The repair bill will run into billions of dollars.

We recently saw the destructive power of hurricanes Milton and Helene, as they cut a path of destruction through various states in the US. They left in their wake flooded businesses, broken roads, power outages, and other problems. The repair bill will run into billions of dollars.

A major storm on the Sun, however, has the potential to dwarf those losses. A recent study by the American Geophysical Union found that under the right circumstances, a solar storm could trigger economic damages of up to almost 50 billion dollars a day. Whilst hurricanes (we call them cyclones in Australia) cause local damage, solar storms have the potential to affect vast swathes of planet Earth at once.
The Sun produces storms all the time — big eruptions of charged particles that race outward at millions of kilometres per hour. Most of the time, these storms miss Earth. But when they do hit, they can knock out satellites, disrupt communications and air travel, and even knock out power grids. In 1989, an especially big storm knocked out power to Quebec, Canada. Smaller storms produce the colourful auroras that we see at high latitudes in both hemispheres.

In fact, the biggest solar storm on record happened in 1859. That storm has been dubbed the Carrington Event, after British astronomer Richard Carrington, who witnessed the megaflare and was the first to realize the link between activity on the sun and geomagnetic disturbances on Earth.

During the Carrington Event, aurorae were reported as far south as Cuba and Honolulu in the northern hemisphere, while southern lights were seen as far north as Santiago, Chile and Brisbane, Australia.

In addition, the geomagnetic disturbances were strong enough that U.S. telegraph operators reported sparks leaping from their equipment; some bad enough to start fires. In 1859, such reports were mostly curiosities. But if something similar happened today, the world's high-tech infrastructure could grind to a halt.

At stake are the advanced technologies that underlie virtually every aspect of our lives. Of particular concern are disruptions to global positioning systems (GPS), which have become ubiquitous in mobile phones, airplanes, and automobiles. In addition, satellite communications, also essential to many daily activities, would be at risk from solar storms. Every time you purchase petrol with your credit card, that's a satellite transaction.

But the big fear is what might happen to the electrical grid, since power surges caused by solar particles could blow out giant transformers. Such transformers can take a long time to replace, especially if hundreds are destroyed at once.

Let’s turn our attention to the evening sky now and forget about disasters for a while. Low in the northeastern sky, the Pleiades, or more commonly known as the Seven Sisters, can be seen glowing like a small bright cloud. Examine them with your binoculars, and they'll transform into a myriad of jewels against the black of the night. The Pleiades is really a cluster of several hundred stars about 425 light-years from Earth. The stars were born about a hundred million years ago from a single large cloud of gas and dust, which makes them all sisters. That seems appropriate, since the Pleiades are the daughters of Atlas in ancient Greek legend.
Keep your gaze fixed to the north-east, but about half-way up the sky. Using the starchart, locate the constellation of Cetus, the whale, and then a star labelled Mira – “the wonderful”. Only, it may not be there!

Centuries ago, skywatchers gave Mira its name because it does something wonderful: it periodically appears and disappears.
Today, Mira's the model for an entire class of stars that do the same thing. Like Mira itself, these stars fade then brighten again over a period of a hundred days or longer. Mira completes its cycle in about 11 months. It reached its brightest for this current cycle in late May and is currently fading and therefore invisible to the unaided eye. It’s predicted to reach its maximum brightness again in April 2025.
At its brightest, Mira is quite brilliant. But it doesn't get that bright every time it peaks; sometimes, it's barely bright enough to see with the unaided eye. And at its faintest, you need a large telescope to see it.
Mira variables are old stars. They've used up the supplies of hydrogen fuel in their cores and ballooned into red giants; stars that are much larger yet cooler than the Sun.

These stars get brighter and fainter because they're expanding and contracting; perhaps as the result of shock waves that begin outside their cores. When the star contracts, it gets hotter, so it looks brighter. When it expands, its surface temperature drops by several hundred degrees, so the star gets fainter.
This rhythmic pulsation can be dramatic. Mira's diameter may vary by almost 100 million kilometres; that’s about two-thirds the distance from Earth to the Sun.

“How far can you see?” is one of the most common questions I get asked when showing someone the night sky.
And during November, we are perfectly placed to answer this question. The Great Andromeda Galaxy (labelled as M31 on the star chart), located low in the northern sky is the farthest object we can see with the naked eye. It is the closest of the large galaxies and contains approximately two hundred thousand million stars, about twice as many as our own galaxy. You can see it as a faint smudge of light away from city lights.

The light from the Andromeda Galaxy takes over 2 and a half million years to complete its journey to the earth. Just think about that. The light from the Andromeda Galaxy had already been travelling for a million years before the very first hominids roamed across the plains of east Africa.

By the time the very first ancestors of modern man started making stone tools in China and Africa, the light had completed over 85% of its journey. Travelling at 300,000 kilometres per second, the light raced across intergalactic space to the Milky Way galaxy. When the slaves of Egypt built the great pyramids 5000 years ago, the light from Andromeda was already well inside our own galaxy.

Almost 2800 years ago, Chinese astronomers observed an eclipse of the Sun. They would have also known of that little smudge of light in the night sky, but would have been totally unaware of what it represented.

The Greek and Roman empires rose and crumbled; Christopher Columbus discovered the West Indies; and Galileo pointed his first telescope to the heavens. Still that light travelled. By the time Neil Armstrong walked on the Moon in 1969, only 55 years remained of its journey.

So, when you next go out on a clear November night and look at that smudge of light that we know as the Andromeda Galaxy, try to imagine that immense journey and all the history that has passed since then.

Planetary observers have a visual feast awaiting them this month. Venus, that brilliant beauty in the western sky rules the early evening. Nothing shines brighter. The glamour body of the solar system, Saturn, is still high in the sky. Its rings will be exactly edge-on to us early next year. Look very low in the west soon after sunset on November 3rd and you’ll glimpse the thin crescent of a 2-day old Moon and just below and to the right of it, the elusive planet Mercury.

The Moon is New on the 1st of November, at First Quarter on the 9th, Full on the 16th, and at Last Quarter on the 23rd of November.

Happy stargazing!!