We have recently seen the destructive power of extreme weather events, such as cyclones and the flooding in southwest Queensland. It left in its 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 found that under the right circumstances, a solar storm could trigger economic damages of up to almost 50 billion dollars a day. Whilst cyclones 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 aurorae 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.

During early May, the Earth crosses the orbit of Comet Halley, and this produces one of the southern hemisphere’s most famous meteor showers, the Eta Aquarids, named for the star in the constellation of Aquarius, from near which the meteor shower appears to originate. If you’re brave enough to venture outside at about 3.00am, look about 10 degrees up the eastern sky. Spend some time looking and you could be rewarded with up to 60 or more “shooting stars” per hour. The best time is around May 5-6.
Comets are small, fragile, irregularly shaped bodies composed of a mixture of dust and frozen gases. Think of a comet as a “dirty snowball”. They usually follow highly elongated paths around the Sun. Most become visible, even in telescopes, only when they get near enough to the Sun for the Sun's radiation to start evaporating the volatile gases, which in turn blow away small bits of the solid material, usually no bigger than dust grains. These are left behind by the comet and form what astronomers call meteor streams.

If the Earth's orbit crosses through a meteor stream, these small particles enter the Earth’s atmosphere at great speed, typically at over 40,000 kms per hour. The friction generated by this re-entry completely vaporises the dust, resulting in a brief bright flash, usually referred to as a shooting star. When we strike a large number of these particles, we experience a meteor shower.

Let’s now turn our attention to the evening sky. Over in the east, Scorpius, the Scorpion (one of the few constellations in our sky that resembles what it is supposed to represent) is difficult to miss. It will keep us company over the coming chilly winter months. Its brightest star, Antares, is a star of gargantuan proportions. If we replaced our Sun with it, then all the planets from Mercury through to Jupiter would all find themselves engulfed within it! Just below the tail of Scorpius, you can find the star clusters designated M6 and M7. Take the trouble to observe these with binoculars. They make a beautiful sight, with many bright stars sparkling like diamonds against a background of gold dust.

In the north-eastern sky, the brilliance of red Arcturus, shadows the other stars in the area, whilst Sirius, the brightest star in the sky begins to perform his mighty dive into the western horizon. It will disappear from our night sky by the end of the month and won’t return to the evening sky until late this year.

Unmistakable, high in the southern sky, is the famous Southern Cross. Surrounding it on three sides is the constellation of Centaurus, the centaur. Its two brightest stars, Alpha and Beta Centauri, are referred to as the Pointers, because they follow the Southern Cross around the sky and always point to it. Alpha Centauri is actually the closest star system to the Earth other than our own Sun, at a distance of just over 4 light years.

The third brightest star in the Southern Cross is Gamma Crucis; you can locate it at the apex of the cross. In the early evening during May, it is the highest in the sky of the stars that make up the Southern Cross. Look at it carefully, and you’ll see that it is a red star. It is a prelude of what will happen to our Sun.

Today, our Sun is a yellow star, steadily fusing hydrogen into helium at its core. Billions of years from now, though, it’ll use up its hydrogen. The Sun will expand, engulfing the planet Mercury, and possibly Venus and even Earth, and its surface layers will cool and redden. In other words, the Sun will become a red-giant star.

But that won’t happen for another five billion years or so. For now, Gamma Crucis is the closest red giant to Earth, at a distance of almost 90 light-years. This bright star produces about as much energy in an hour as the Sun does in an entire week.

As a red giant, Gamma Crucis is nearing the end of its life. Someday, it’ll cast its outer layers into space, exposing its hot, dense core. Eventually, over billions of years, the leftover core will cool, leaving only an invisible cosmic cinder.

Between the Southern Cross and the southern horizon, you’ll notice two small fuzzy blobs in the sky – these are the Large and Small Magellanic Clouds. You’ll need a dark sky to see these. When the first Portuguese explorers sailed into southern waters, they saw these faintly glowing clouds that weren't visible from their homeland. They named the little clouds for Ferdinand Magellan, the explorer who'd organized the first trip around the world. The Magellanic Clouds became beacons for southern navigators.

The only bright naked eye planet in the evening sky during May is Mars, located within the constellation of Cancer, the crab. A very disappointing sight in a telescope, as it is over 213 million kilometres from Earth at the beginning of May. That recedes to 252 million kilometres by the end of the month. We really need to wait until the early 2030’s before the 2 planets come close enough to each other to afford great views through a telescope.

The Moon is at First Quarter on May 4th, Full on the 13th, at Last Quarter on the 20th, and New on May 27th.
Happy observing!