The Perseids are usually the biggest meteor show of the Northernern summer but a pesky full moon will make them hard to see in two weeks time. But that means that it’s the Southern Delta Aquariids time to shine, unencumbered by the silver light of the Moon, as they peak tomorrow night.
This meteor shower lasts from mid-July to mid-August and is easily visible in the Southern Hemisphere where the radiant – the areas where the meteors seem to come from – is high in the sky. The spectacle is also visible in the Northern Hemisphere when looking south.
The hourly rate of this shower is estimated to be 25 per hour, according to the International Meteor Organization. That's about one meteor striking across the sky every couple of minutes. With an entry speed of 41 kilometers (25 miles) per second, they are of medium speed. More intense showers have been witnessed in previous years but this year doesn’t seem to be one of them.
Meteors are caused by debris left around Earth’s orbit by a comet or asteroid producing an outburst or falling to pieces. The parent body of this meteor shower is not known, but a likely candidate is Comet 96P Machholz, a sun-grazing comet, that gets as close as 18.5 million kilometers (11.5 million miles) from the Sun.
2
