Annual Variations in Meteor Shower Fluxes from Radar Observations

Many meteor showers have different maximum activity levels in different years. The activity of the Geminid meteor shower, whose parent is asteroid 3200 Phaethon, is currently increasing, according to models of the stream evolution and visual observations [1]. The
$\eta$
-Aquariid shower, which comes from comet 1P/Halley, shows occasional outbursts where the activity increases by a factor of two or more [2]. Understanding the variations in meteor shower activity helps to constrain models of meteoroid stream evolution, which in turn improves predictions of the future activity of showers. It can also shed light on the past activity of comets or asteroids and the mechanisms by which they lose mass.