Looking for something spectacular to brighten up a cold, dark winter night?
Well, this weekend may have something in store: not one, not two, but three meteor showers active at the same time, combining to deliver a celestial fireworks display almost all night long.
While the best night for viewing will be the evening and night of Saturday, July 30 into the early hours of Sunday morning, all three showers will be near their maximum starting tonight. So you’ll have plenty of opportunities to see the show barring bad weather or other commitments.
Best of all, there will be a new moon, which means there won’t be much glare to spoil the show.
What are meteor showers?
The solar system is full of remnants left behind from the formation of the planets more than 4.5 billion years ago. Some of this debris (comets and asteroids) move in orbits that cross Earth’s path around the sun.
Every time these comets and asteroids hurtle toward the sun, they throw up debris. Over hundreds or thousands of years, their orbits become entangled in vast streams of dust.
The Earth continually passes through these streams of debris as it moves around the sun, giving rise to the annual meteor showers. Every year, we return to the same spot in our orbit, encounter the same debris stream, and put on another pleasant spectacle as this debris burns harmlessly 80 kilometers above.
In the depths of the Australian winter, Earth moves through a patch of space where three debris streams intersect our planet’s orbit. These three streams give birth to the protagonists of this weekend’s show: the South Delta Aquariids, the Alpha Capricornids and the Austrinid Pisces.
The International Meteorological Organization has animated 3D visualizations of the South Delta Aquariid and Alpha Capricornid meteor streams, showing how the debris is distributed through space.
The 3D visualization of the Alpha Capricornid meteor stream lets you move around the solar system and see the debris stream in action. (Provided by: International Meteorological Organization)
A tale of three rains
So let’s introduce the stars of the show.
The southern delta aquarids are the most active of the three showers, with the meteors moving the fastest. Most of the meteors you’ll see this weekend will likely be members of this stream.
The origin of the South Delta Aquariids is the subject of some debate. They are one of several meteor showers apparently linked to a parent object, as if a large comet collapsed long ago, leaving behind a large amount of debris, which may include fragments large enough to be comets in their own right.
Over millennia, the debris has spread, so that Earth bumps into it several times each year. At the moment, the South Delta Aquariids are tentatively bound to a comet called 96P/Machholtz, which is the most active object in the debris stream.
The South Delta Aquariids have been known to offer some surprises. In 2006, they produced a burst, with some people seeing more than 60 meteors per hour at their peak. No breakouts are predicted for this year, but you never know what might happen!
The second of our rain triumvirate is the Alpha Capricornids. These produce the slowest meteors of the three showers. They also have a reputation for being a “fireball” shower, often producing spectacular meteors that outshine the brightest stars.
These are the meteors you are most likely to capture on film and provide a great opportunity to practice astrophotography.
The final rain, the Austrinid Pisces, are perhaps the least studied of the three. Like Alpha Capricornus, they are a minor shower that produces only a few meteors per hour, even at their peak. Its meteors are medium speed.
So where and when should I look?
The key for observers is to determine when the rain “radiant” will be above the horizon. The radiant is the point in the sky from which all meteors in the shower appear to radiate.
Meteor showers are named after the location of their radiant. The Alpha Capricornis, for example, radiate from a point close to the star Alpha Capricorni.
The meteor showers will be high in the eastern sky around 11:00 PM local time. The planets Jupiter and Saturn, as well as the bright stars Fomalhaut, Altair (in the northeast), and Achernar (in the southeast) will be visible, weather permitting. (Provided: Museums Victoria/Stellarium)
In the case of our winter trio, we are very lucky. The three radiants rise from early to midnight from Australia and reach a reasonable altitude around 10pm.
As a result, you can see meteors anytime after mid-afternoon. The best rates will be visible from 10 p.m. until dawn.
Once you’ve set up in a comfortable spot from which to observe, try to avoid looking at your phone. You want your eyes to adjust properly to the dark so you can see the faintest meteors. Looking at a screen, even for a second, will bring you back to square one.
In the morning around 5am local time on Sunday, July 31, meteor showers will appear to radiate from the western sky. The planets Saturn, Jupiter and Mars should also be visible. (Provided: Museums Victoria/Stellarium)
We find the best place to look when we see a meteor shower is about 45 degrees above the horizon, and about 45 degrees to the left or right of the radiant.
Therefore, in the early evening, it would be better to face east or northeast. At midnight, and immediately after, it would be best to look north. And in the hours before dawn, you should face west or northwest.
And don’t worry once it’s over! While these three showers are shaping up to put on a decent show, they aren’t the best meteor event of the year. These are the Geminids, coming out in December. So there is still a lot to look forward to!
Jonti Horner is Professor (Astrophysics) at the University of Southern Queensland and Tanya Hill is an Honorary Fellow at the University of Melbourne and Senior Curator (Astronomy) at Museums Victoria. This piece first appeared on The Conversation.