Particle ejection year from 1P/Halley as a function of impacting year at the Earth for the η-Aquariids (circles) and the Orionids (squares). Symbols are color coded as a function of the number of impactors (see sidebar). When several trails from different ejection epochs are involved in producing impactors (e.g., in 2012 and 2013), connected symbols frame the ejection period. The rectangles illustrate the periods when the ejection epoch occurred with 1P/Halley trapped in the 1:6 (red) and 2:13 (blue) MMR with Jupiter. Meteoroids ejected during these intervals may remain in the MMRs and form comparatively denser “clumps” in the stream. Vertical lines show the years of recent η-Aquariid (red) outbursts in 2004 and 2013 and Orionid (blue) outbursts in 2006-2007.