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Tuesday, August 07, 2018

 

Australian Perseid Meteor Shower - Morning August 12-14, 2018

Perseid radiant as seen from Darwin at 5:00 am local time, August the 13th, looking north. Click to embiggen.Perseid radiant as seen from Brisbane at 5:00 am local time, August the 13th, looking north. Note how much lower the radiant is than in Darwin.

You may have seen Facebook posts (or twitter notifications ) saying that on August 12/13 there will be a meteor shower that will be the brightest ever seen by mankind with Thousands of shooting stars. Well nope. This is the Perseid meteor shower, and though a reliable and good northern hemisphere shower, and hundreds of meteors may be seen under the very best condition, this year the rates will be around usual, nice but not spectacular.

The Perseid Meteor Shower runs from July 17–August 24, and peaks in the early morning between Saturday August 12 - Sunday August 14 AEST. The midpoint is August 12, 20h UT to 13, 08 h UT (6 am on the 13th AEST-6pm AEST on the 13th).  See the International Meteor Calendar for 2018 for further details.

Despite this being a quite reasonable meteor shower in the northern hemisphere, for most of Australia the radiant is below the horizon, and only the very occasional meteor will be seen shooting up from the northern horizon. Only observers in northern Australia (at the latitude of Brisbane or further north) will have decent rates.

This is a good year, while the peak occurs after sunrise in Australia, it still occurs reasonably close to radiant maximum height, this years peak is about usual (with a ZHR of 110 meteors per hour predicted) the Moon is near new and will not interfere.

However, these ZHR predictions are ideal rates for sites with the meteor radiant directly overhead, under the darkest possible skies with nothing obscuring the sky. From Australia, we will see much lower rates than these ideal ones. Anyone south of Brisbane will see only the occasional meteor, say maybe one or two per hour (or less), the further north of Brisbane you are, the more meteors you will see.

You can check predictions for your local area at the NASA meteor flux estimator (choose 7 Perseids and 12-13 or 13-14 August 2018). Unfortunately, both Chrome and Firefox have changed their security settings to prevent plugins from running, and the flux estimator only runs under Internet Explorer now.

People around the latitude of Darwin have the best chance of seeing meteors, possibly as many as one every 3 minutes at the peak (see table below). At the latitude of Alice Springs  you will see around a meteor every 6 minutes, Cairns is intermediate between Darwin and Alice Springs. At the latitude of Brisbane you will see a meteor every 10 minutes (again, see table below).

To see the meteors, you will need to be up from around 3:30 am local time on the morning of the 12th, 13th or 14th (yes, a really horrible hour of the morning), with best views 4:00 am-5:30 am on the 13th. The meteor shower will be located due North, with the radiant just above the northern horizon (see charts above). Cloud cover predictions can be found at SkippySky.

When you get up, allow at least 5 minutes for your eyes to adjust, and be patient, it may be several minutes before you are rewarded with you first meteor, then a couple will come along in quick succession. Choose a viewing spot where you can see a large swathe of sky without trees or buildings getting in the way, or with street lights getting in your eyes. The darker the spot the better (but do be sensible, don't choose a spot in an unsalubrious park for example).

A lawn chair or something similar will make your observing comfortable (or a picnic rug spread on the ground and a nice pillow), and having a Thermos of hot coffee, tea or chocolate to swig while watching will increase your comfort. (Here's some hints on dark adaptation of your eyes so you can see meteors better).

The following table show the predicted peak rates at around 5 am local time on the mornings of the 12th, 13 and 14th of August for a number of cities under dark sky conditions. Rates will be similar at the same latitude as these cities, and rates will be intermediate at spots between these cities.

TownMorning August 12Morning August 13Morning August 14
Alice Springs7 meteors/hr10 meteors/hr9 meteors/hr
Brisbane4 meteors/hr6 meteors/hr5 meteors/hr
Darwin15 meteors/hr24 meteors/hr20 meteors/hr

Rates on the morning of the 15th are similar to that of the 14th. Note, those of you who have Stellarium, in version 13 they have added meteor shower radiants (rates set in the planets dialogue, F4). However while the radiants are shown, the simulated meteors come from random points in the sky, not the radiants.

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