This page was last amended on 1st August, 2010

Meteor showers, August 2010

Arguably the best meteor shower of the year, the Perseids, occurs in August - see below.  But first a little background on meteors in general. 

There are essentially two sorts of meteors (colloquially known as "shooting stars") , sporadic meteors and annual meteor showers.

Sporadic meteors appear at random in any part of the sky and at any time of the year, and annual showers are visible only at specific times of the year.  Also annual showers generally appear to come from specific parts of the sky – the “radiants”.  The showers are named after the constellations in which their radiants are found – Geminids, originating in Gemini, Leonids originating in Leo, etc.  The suffix “-ids”, tacked on to the constellation name, means “belonging to” or “connected with”.

But even sporadic meteors are not totally random – there are more seen at some times of the year than at others, and September is known for one of the highest rates – up to 20 meteors per hour.  On the other hand, many of the meteor showers, as opposed to the sporadics, are associated with comets that shed a dusty debris stream along the comet's orbit. When the Earth travels through this stream at a later date, we see a meteor shower.

So on to this month’s big event – the best meteor  shower of the year.  It also promises to be particularly good this year because the Moon sets quite early so there is no Moonlight to wash away the fainter meteors.

There are two really good meteor showers each year: the Perseids in August and the Geminids in December.  There are more Geminids per hour than there are Perseids, but in one respect the Perseids win hands down – the weather!  I’m sure we all prefer sitting to watch the sky during a warm Summer night than during a cold Winter one!

We can normally see about 6 sporadic meteors per hour in the summer, but on 12th August we can see up to 80 bright streaks of light per hour shooting across the sky.  They are tiny specks of dust burning up in the earth’s atmosphere at about 35 miles per second!  These specks of dust are debris left behind by the comet Swift-Tuttle occasionally coming close to the Sun during its 130 year orbit.  You can see some Perseids from the last week in July until about 20th August, but the night of 12th August is when they are at their best by far.  They can be seen in any part of the sky, but appear to originate from the constellation of Perseus about 50 above the N horizon.