Astroblog: Orionid Meteor Shower, Morning 21-23 October 2018

Thursday, October 18, 2018

Orionid Meteor Shower, Morning 21-23 October 2018

Morning sky as seen from Adelaide facing north-east at 2:00 am ACDST on 22 October, the Orionid radiant is indicated with a starburst. Similar views will be seen elsewhere in Australia at an equivalent local time. Click to embiggen.

The Orionids are a worthwhile shower that somewhat favours the Southern Hemisphere,best seen between 2-5 am, the radiant, the point where meteors appear to originate from, being just under Betelgeuse, the bright red star in Orion.

If you draw an imaginary line between Procyon and Aldebaran, then drop another imaginary line from Betelgeuse to the horizon, the radiant is just next to the intersection of those two lines.

The Orionids are the debris from Halley's comet. The Orionids maximum is on October 21 UT (October 22 Australian time).

This year the nearly full Moon interferes with the shower, but is far enough away that you can block its light out for reasonable viewing.

The best viewing is the morning of the 22nd, when between 3-5 am under dark skies you should see about a meteor every 3-4 minutes, although reasonable rates will be seen the mornings before and after (see table below).

You can find out the predicted rates for your location using the NASA meteor flux estimator (use 8 Orionids and make sure you set the dates to 21-22 October 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.
You can follow the progress of the shower at the IMO Orionids live page.

If you decide to 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). Look to the north-east, and the distinctive red star Betelgeuse below the saucepan will be easy to spot. The meteors should originate just below here. However, let your eyes roam a bit to pick up meteors that begin their "burn" a fair distance from the radiant.

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 adaption 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 21st, 22nd and 23rd of October for a number of cities under dark sky conditions (rates under suburban or city light conditions will be lower). Rates will be similar at the same latitude as these cities, and rates will be intermediate at spots between these cities.

Town	Morning October 21	Morning October 22	Morning October 23
Adelaide	10 meteors/hr	14 meteors/hr	11 meteors/hr
Brisbane	12 meteors/hr	16 meteors/hr	15 meteors/hr
Darwin	15 meteors/hr	19 meteors/hr	19 meteors/hr
Perth	11 meteors/hr	15 meteors/hr	12 meteors/hr
Melbourne	10 meteors/hr	13 meteors/hr	10 meteors/hr