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We are only a few days away from the maximum of the Perseid meteor shower ... and it could be a rather good one this year.
Perseid meteor activity can be seen each year from the third week of July through to the third week of August, but the best rates are seen during a few nights around August 12th. Perseid meteors are those whose paths when traced backwards across the sky appear to have come from a small area of sky near the top of the constellation of Perseus (see later for chart).
The "normal" Perseid maximum is predicted for Aug 12d 13h UT, which means that the best observed rates from this for UK observers are likely to occur late in the night of Aug 11-12 (Thurs-Fri). From a reasonably good UK observing site, you might expect to see 30-40 Perseids (plus half a dozen or more sporadics) per hour at this time. (Don't be misled by the "ZHR" of 80 often quoted - rates this high can only be approached from exceptional observing sites). Good rates should also be seen during the nights of Aug 10-11 (Wed-Thurs) and Aug 12-13 (Fri-Sat). Although a gibbous Moon will be present initially, it will be low in the S-SW sky for UK observers and will set around the middle of the night, leaving the later part moon-free.
It is known, however, that there is a 12-year resonance in the orbit of the Perseid meteor stream, related to the gravitational effect of the planet Jupiter. This led to the Perseids producing higher than usual rates at maximum in 1968, 1980, 1992 and 2004. Observers hope that 2016 will continue this sequence. There is no chance of a Perseid meteor storm, but we might hope to see rates approaching double their normal level for a while (possibly increasing the rate specified above to 50-60 per hour) ... but there is no guarantee of this! The predicted timing of any enhanced rates from this resonance seems to depend on who you ask. However, almost all predictions specify times during the night of Aug 11-12 - so the best approach will be to stay out observing as long as you can and hope that you get lucky.
The usual advice regarding meteor observing applies:
- Find as dark an observing site as possible, with a clear view of the sky
- Keep your eyes dark adapted - use a dim red torch when recording what you see
- Don't look directly at Perseus, look at an area of sky 30-40 degrees away from the radiant and at an altitude of around 50 degrees above the horizon
- Stay out as late as possible. Although Perseids can be seen throughout the night, observers who stay out later are rewarded with high observed rates due to Perseus climbing higher in the sky.
The chart below shows the position of the Perseid radiant for the night of maximum. The radiant position actually moves about a degree per night right to left. On Aug 7, for example, it is located close to the Perseid Double Cluster.
More advice regarding Perseid observing can be found on page 25 of the latest issue of Popular Astronomy and in this guide
A guide to visual meteor observing in general can be found here
Do let us know what you have seen. You can email your results to firstname.lastname@example.org, or mention @popastro in your Tweets
Added by: Tracie Heywood