Shower comments
Quadrantids: Named after the disused constellation Quadrans Muralis, the Wall Quadrant, now amalgamated into northern Boötes. The peak lasts only a few hours, so can be easily missed, while the radiant, though circumpolar from Britain, is very low in the evening hours, rising overnight to be highest towards dawn. The Earth should pass closest to the node of the meteoroid stream around 07:30 UT on 2012 January 4, and theoretical considerations suggest there is the possibility of a strong, probably quite short, peak happening within a few hours of that time. A waxing gibbous Moon on January 3/4 makes this a tricky year for observing unfortunately, but it should set for most UK sites within 45 minutes of 04h, leaving a couple of pre-dawn hours with darker skies. Peak ZHRs are occasionally variable (recent highs were 180 in 1992 and 160 in 2008 - for the latter only, see ENBs 236 & 238), and a second, lesser, maximum has been found sometimes since 2000, mainly in radio observations, about 9-12 hours after the main peak. Thanks to recent IMO video reports indicating weak activity is apparently present from December 28 to January 12, the shower's activity period has been extended accordingly, though it is likely visual observers will struggle to see any Quadrantids other than on a few nights either side of the maximum, as this was typically the case in the past. Medium-speed meteors.
Lyrids: Peak rates are normally ~15-20, but short-lived, more active bursts have been recorded sometimes, most recently in 1982 (when ZHRs were ~90). The maximum time can vary. It is expected between roughly 21h on 2012 April 21 to 09h UT on April 22, so is suitable for overnight observing from Britain. New Moon occurs on April 21 and so moonlight is not a problem in 2012. The radiant is low in the sky at the start of the night and gains altitude as the night progresses. The radiant is on the Hercules-Lyra border at the peak, not so near Vega as some people expect. Medium-speed to swift meteors. The probable parent body is Comet Thatcher of 1861 (whose orbital period is about 415 years).
η Aquarids: This shower is never easy to see from the UK, as its radiant rises shortly before dawn, about 01:30 UT, but occasional members have been spotted by British watchers. A further complication in 2012 is that peak activity occurs only 2 days before Full Moon. Activity is marginally easier to note from these latitudes after the peak, when the radiant rises a little earlier. An excellent shower in pre-dawn dark skies from the southern hemisphere though, and the rates, which may be variable, could be only a little down on their possibly cyclical highest in 2012 (variable ZHRs from ~40-85). Rates often remain good for several days across the maximum too. Very swift meteors, often with long paths because of their low radiant, and fine persistent trains. The stream was laid down by Comet 1P/Halley, along with their autumn twin the Orionids. Halley was last at perihelion in 1986 (period around 76 years).
June Boötids: An unpredictable source, the June Boötids produced an unexpected outburst in 1998, when ZHRs of 50-100+ were observed for over 12 hours, with rates seen on just one date. Before this, only three returns of the shower were known, from 1916, 1921 and 1927. Another ZHR ~50 outburst happened on 2004 June 23, but a similar event predicted for 2010 June 23/24 proved disappointingly very weak (ZHRs < 10; see ENBs 291, 292 & 295). The shower is associated with Comet 7P/Pons-Winnecke, last at perihelion on 2008 September 26. Late June's First Quarter Moon (on June 27) will be low in the sky and so will add little to the problem of Britain's short, twilight midsummer nights for watchers - and even casual observers here easily spotted the 1998 return. No activity is expected this year, though recent IMO video results have indicated very weak rates may happen annually from the shower, on or around June 24, so worth keeping watch then just in case, and also around the 1998 peak's repeat time, on June 27. The June 24 video June Boötids were radiating from an area about 10° south of the expected one, however. Very slow meteors.
δ Aquarids: Although the summer ANT radiant is uncomfortably nearby to their north, this shower should be strong enough to stand out as distinct from the ANT meteors. It is not seen at its best from the UK, thanks to its southerly radiant. Great care must be taken to separate δ Aquarids from ANT and CAP meteors in July-August. Minor adjustments to their "last active" and maximum dates have been made for 2011, though the better rates may persist at similar levels from July 28-30 anyway. Moonlight will be a serious problem near maximum, being between First Quarter and Full Moon. Medium-speed meteors.
α Capricornids: Slow meteors, occasionally beautifully bright, but their activity is never very high. Unfortunately, moonlight will seriously hinder observations of activity around maximum this year. The shower radiant actually overlaps that of the ANT and this has caused problems for visual observers recently, who have struggled to identify the CAP as a distinct source.
Perseids: From 1988-1999, the Perseids produced a double maximum, but from 2000-2003 only one main peak was seen. The primary peak was associated with Comet 109P/Swift-Tuttle's most recent perihelion in 1992 (period ~130 years). Highest activity between 2004-2010 has been variable, with average ZHRs from ~80 to 180 in different years (180 in 2009 only, perhaps topping-out around 230 briefly; see ENBs 273 & 275), and sometimes with several maxima. No predictions of an enhanced peak are in-force for 2011, with the normal maximum due on Sunday August 12 between 07h-19:30 UT, perhaps at its highest near 11h. Observations of much of the rise towards maximum in 2012 will be hindered by the Moon, which is Full on Aug 2 and will be very slow to move out of the evening sky in the week which follows. However, by maximum night it will be a waning crescent in Taurus and therefore an irritation rather than having a significant effect on observed rates.
κ Cygnid: Rates are generally low, but occasional bright fireballs (possibly in periodic bursts every 6 to 7 years) have been seen from this source. Slow meteors. Moonlight will not be a problem in 2012. Recent IMO video results have indicated the maximum may be nearer August 14 and also found problems in defining the radiant position.
α Aurigids: Recent IMO visual and video analyses have resulted in a complete revision of details for the swift-meteor, generally minor, near-Auriga showers, active at times between late August till October. Even so, there may be others apart from the three currently recognised - the α and δ Aurigids and the September ε Perseids. The parameters for all have been amended in our Showers List table. The α Aurigids are probably associated with Comet Kiess, last seen in 1911, whose period is around 2500 years, unusually long to produce what appears to be an annual shower. A bright-meteor, if badly moonlit, outburst occurred from them on 2007 September 1, when ZHRs reached ~130 (see ENBs 228 & 233). It was predicted in advance, but other unexpected outbursts have happened too, giving estimated ZHRs of ~30-40 in 1935, 1986 and 1994. The maximum is due around 19h UT on Aug 31 in 2011, and so badly effected by the Full Moon. The radiant can be usefully-observed from midnight UT onwards in Britain.
September ε Perseids: This shower seems to have been that which produced an unexpected outburst of swift, bright meteors on 2008 September 9 (see SPA ENBs 253 & 254). However, its radiant location at the peak is actually closer to β or ρ Persei than ε! The shower is properly observable from the UK by 22h UT, and can be watched thereafter all night, something which is helpful this year.
Draconids: Past showers have typically happened only when their parent comet, 21P/Giacobini-Zinner (period around 6.6 years), was at perihelion in the autumn, as in 1998, when short-lived ZHRs of circa 700 occurred. Other returns have given rates up to storm levels (the last storm was in 1946). A largely unexpected outburst happened in 2005 (when the comet returned that July; see ENBs 184 & 185), so it is worth checking on in most years, just in case. Another brief outburst, reaching a ZHR of 250-300 occurred on 2011 Oct 8. The comet passed through perihelion in early 2012 and so high rates are not expected this October. However observations at similar intervals after previous perihelion passages have suggested that low ZHRs of 5-10 may still be visible and so it is worth watching for such activity. Very slow meteors, and apparently very fragile meteoroids. The radiant is best placed for observation during the evening, whereas the Moon which is at Last Quarter and in Gemini will only be present later in the night
Southern Taurids: Like their Northern branch (see below), both showers are associated with weakly-active Comet 2P/Encke, which has the shortest orbital period of any comet known (3.3 years). The two showers give low rates, but occasional fireballs spice up their prospects. Recent IMO visual and video investigations have led to significant changes in how we think of the Southern Taurids particularly, with amendments to the activity period and especially the maximum, which now appears to happen almost a month earlier than had long been thought, around October 10. It is likely not a very sharp peak however, while this earlier date means the meteors then will be radiating from an area around the eastern Pisces to northern Cetus borders, rather than from well within Taurus as used to be the case. Sadly, October's full Moon occurs on the 28th. Slow meteors.
Orionids: Linked to Comet 1P/Halley, like their May counterpart, the η Aquarids. ZHRs are usually quite good for two to three nights centred on their peak, and may be about 25 this year from a recent IMO analysis. Activity could be still stronger, following the higher returns (ZHRs ~35-80) found from 2006-2010 inclusive, when such rates persisted for two or more nights at these levels. No repeat is expected this time. A quite strong sub-maximum has been noted occasionally around October 17-18 as well (most recently in 1998). Maximum night, October 21, is a Sunday, but good rates should also be seen during Oct 20-23. The Moon is at First Quarter on Oct 22 in the Sagittarius/Capricornus area and so will provide some interference while the radiant is still low in the sky, but will not be an issue later in he night. Very swift meteors, with good persistent trains.
Northern Taurids: In the period leading up to the slow-meteor Northern Taurid maximum, around late October to early November, sometimes there can be an especially fireball-rich spell (most recently in 2005 - for links see the Meteor Section Reports 2005 webpage), during one of the Taurid "swarm" returns. The most recent "swarm" event was in 2008, which produced good rates for a few days during this spell, but no unusual fireball numbers (links to reports are available on the Meteor Section Reports 2008 webpage). The next "swarm" return may occur in 2012. There are fewer changes for the Northern Taurid parameters than those of their Southern counterpart discussed earlier, but the activity period has been amended to start in late October and end in mid December. The maximum is scheduled for November 12, close to New Moon.
Leonids: The proximity of the shower's parent comet 55P/Tempel-Tuttle helped produce strong to storm returns during 1998-2002 inclusive, at perihelion last in 1998 (period 33 years) and there have been strong enhancements in rates due to encounters with lesser filaments in later years, most recently in 2008 and 2009. Peak rates in 2012 will probably occur on November 17th (a Saturday), although there is also a prediction of a possible enhancement to a ZHR of around 10 at around 06hUT on November 20th. Moonlight will not be a problem around maximum in 2012 as on maximum night it lies in Sagittarius and so sets before the radiant rises. Very swift meteors, often trained. Note that the activity period has recently been extended to run almost throughout November thanks to the latest IMO findings.
Geminids: Associated with asteroid 3200 Phaethon, rather than a comet, and their meteoroids seem to be rather denser than those in most meteor showers too. Good rates can be seen for around two nights over their peak, but drop away very quickly after the maximum. Unlike many meteor showers, they are easily-observed throughout the night. Regular British observers often consider them the best, reliable, annual shower of the year visible here at present, though the winter weather can be trying. Medium-speed, often bright, meteors. Their peak is due on 2012 Dec 13-14 (Thurs-Fri), most likely within a few hours of 23:30. New Moon occurs on Dec 13 and so moonlight will not be a problem in 2012.
December Leo Minorids & Coma Berenicids: The minor Coma Berenicid shower underwent a degree of confusion in recent times, after IMO video results found apparently identically very swift, mostly faint, meteors radiating from an area about 15° west of where previous visual observations had suggested it should be, as well as from the anticipated radiant. It now seems there may be two minor showers active here, of which the December Leo Minorids is marginally the stronger, and apparently the longer-lasting. Initially thought that both peaked around December 20, the Coma shower is now believed to reach its weak maximum a few days sooner (and from a somewhat different position than earlier indicated). It may be that visual observers will struggle to identify the sources as separate, given previous apparent difficulties in this respect. With these shower only being readily observable lete in the night, moonlight will not be too much of a problem. The December Leo Minorid radiant is usefully-observable after 22:30 UT, while the Coma Berenicid radiant area is so-placed only after 01h.
Ursids: Linked with Comet 8P/Tuttle (period around 13.5 years; last at perihelion in late January 2008). Their peak rates can be quite variable, from ~10-50+, with especially good activity last in 1986. Theoretical work has suggested some enhancements occur about six years after the comet's perihelion, others near years when the comet is at perihelion (though why this latter should happen is unclear, as the comet's orbit currently passes a little outside the Earth's orbit). These theoretical considerations are only a rough guide to reality however, as enhanced ZHRs between ~25-40 were reported from 1988, 1994, 2000, 2006, 2007 and 2008, since the stronger 1986 return. With First Quarter Moon occurring on Dec 20 in Pisces, observations in the first half of the night will suffer serious moonlight interfence, but there will be a moon-free period later in the night. The radiant, in Ursa Minor, is circumpolar from Britain.
Antihelion Source comments
This Source has a large, diffuse radiant area near the ecliptic, present most of the year, which tracks along slowly, roughly opposite the Sun in the sky, hence its name. Activity from it is never high, and observed rates can be virtually nonexistent for UK watchers when the radiant area is at its most southerly, from May to July. Some near-ecliptic sources are strong enough to stand out from it, such as the SDA, and possibly the CAP, in late July, while the two autumnal Taurid showers are so strong they effectively replace the ANT while they are present. Medium speed meteors, comparable in brightness range to the sporadics. You will need to extrapolate the radiant's centre for dates not listed, or see the ANT radiant drift chart in the current month's meteor activity webpage, accessible from the Meteor Section's homepage.