The Perseid meteor shower is at its maximum on the night of August 12 and into the early hours of August 13. Under favourable sky conditions you can generally expect to see somewhere between 60-100 meteors per hour.
The moon is not ideal this year in the early part of the night, but it does set around 12.30am on August 13, so late owls will have excellent dark skies from then on until at least 4am. If you are not a late owl it is still definitely worth heading out after dark. Before the Moon sets there is also a lovely alignment with Saturn and Mars to watch out for on the night of August 12.
Meteors are caused by small particles, typically the size of a grain of sand, burning up in the earth’s atmosphere. The Earth travels around the sun at 30km/s (108,000 km/h) and at this speed pretty much anything that gets in its way becomes super-heated very quickly and vaporised, burning brightly for a fraction of a second and giving the characteristic streak of a meteor.
Some meteors come from particles that are a little bigger and these burn more brightly and for longer, and if you’re lucky you might even see ones which break up into a dazzling spectacle that resembles a celestial firework.
Unfortunately, there is no way to predict when such a meteor might happen, so patience is the friend of the meteor watcher! In exceptional circumstances, where the particles are big enough they make it all the way through the Earth’s atmosphere and land on the ground. These are called “meteorites”. Meteorites are rare, but big ones can wreak havoc — just ask the dinosaurs. Every year we seem to hear that this year will be “the year” for the Perseid meteor shower, and this year is no exception. Predictions of up to 150 meteors per hour have been made and if they turn out to be correct then this will be truly a spectacular cosmic event.
The best way, really the only way, to see meteors is with the naked eye. Meteor showers like the Perseids are named after the constellation from which they appear to originate. This is an optical illusion, but a handy one for the purposes of naming the showers. The Perseids appear to come from the constellation of Perseus, which is low on the northern horizon at sunset — but just look roughly overhead and away from the Moon for the best chance to see some.
As always, give your eyes five or six minutes to adapt to the dark if possible. (For further notes on the Perseids and more observing information see August’s SkyMatters Newsletter at www.bco.ie/skymatters.)
The second event to keep an eye open for is the close encounter between Jupiter and Venus just after sunset on the evening of August 27. This so-called “conjunction” will see the two planets separated by only 0.06 degrees, or 1/500th of the diameter of the full moon.
Meteors bring somewhere between 35,000-80,000 tons of new material to the Earth every year. Most is in the form of microscopic particles, but the odd few can be found as small rocks. Antarctica is a good place to look for meteorites because they are easily distinguishable against the white background of the snow and over the past 30 years more than 33,000 have been found there.