For meteor shower enthusiasts like me, there's another chance to see a minor shower this week, as the Delta Aquariid meteor shower start up tonight and persist for the next week and a half.
The Delta Aquariids isn't one of the more spectacular meteor showers we see during the year, and the view this year is spoiled somewhat due to the light from the waning gibbous moon. However, there's still a good window of opportunity for ideal viewing. The constellation Aquarius (where the shower appears to radiate from) rises above the horizon at around 9 p.m. (local time), but if you can get out and away from the city lights from about 10:30 p.m. to 11:30 p.m. (local time), that will be between when the sky gets completely dark and when the moon rises. Aquarius will be in the east for that time, but just look up to see the meteors streak overhead.
The meteor shower reaches its peak in the early morning hours on July 29th, and with the most ideal conditions, this shower delivers about 15-20 meteors per hour.
There's a couple of unusual things that set the Delta Aquariids apart from other meteor showers, though.
The first is that there are actually two Delta Aquariid meteor showers. The first shower, the Southern Delta Aquariids, is going on now, peaking on July 29th, and continuing through until August 6th. The second shower, the Northern Delta Aquariids, peaks in mid-August. The meteors for these showers come from two different comets, that both flew along roughly the same path through the inner solar system, so the meteors appear to radiate out from roughly the same spot in the sky (near the star Delta Aquarii).
The second is that the comet that formed the Southern Delta Aquariids — Comet 96P/Machholz — has a very unusual composition, compared to other comets we see. This might just mean that it's from an isolated part of our solar system's Oort cloud — the spherical cloud of icy objects that's thought to extend from beyond the orbit of Pluto out to around 1 light year from our Sun. However, it's also possible that it could be an alien visitor to our solar system!
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Some tips for viewing:
• Check your local weather report for cloud conditions before you go out. No sense in heading outside if you're not going to be able to see the stars. An excellent site to use is the Clear Sky Chart. Find the chart for your location (or as close as possible) here, and then follow the guide below your chart to know how to read it.
• Find somewhere dark. That's a bit obvious, but you might be surprised by exactly how many stars and other astronomical objects we miss out on seeing because we live under streetlights and lighted signs nearly all our lives. Even getting just outside the city might not help, because light pollution is pretty far-reaching, and it 'accumulates' with all the sources from cities around as well (southern Ontario is inundated by it). Also, try to be watching from somewhere where there aren't any direct light sources in your field of view. There's a link to the light pollution conditions below the clear sky chart, or you can try using the Dark Sky Finder site to locate good viewing locations near you.
• Give yourself some time for your eyes to adjust to the dark. It varies from person to person, but it typically takes about 20 to 30 minutes for your eyes to completely adjust to the darkness.
• Dress accordingly. It's pretty warm these days, but it'll cool down when you're out skywatching. Also, you might end up walking through a park or wilderness to find a good place to watch, and you may end up sitting or lying on the ground while watching, so make sure you're wearing clothes you'd be comfortable hiking in. Bringing along a blanket to sit or lie down on would also be good. Bringing a good insect repellent couldn't hurt either, since mosquitoes tend to be most active from dusk to dawn.
• If you plan on being out for awhile, bring along a thermos of coffee or hot chocolate, just in case. It might get cool out and it'll give you some energy too.
• Try watching on any night the shower is going on, but if you can, save your trip out for the nights closets to when the shower peaks. You can always catch some good meteors on any night of the shower, but your changes get better right around the peak.
• Remember that when a time is listed for the best viewing of a meteor shower, that's your local time, no matter what time zone you live in. However, the exact day and time of a meteor shower's peak is usually in Greenwich Mean Time, so you'll have to adjust for your local time zone, if necessary.
(Image created by author, using Stellarium 0.12.0)
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