Rare outbursts in activity can occur when the Earth travels through a denser part of the cometary debris stream; for example, in 1998, rates suddenly spiked and spiked again (less spectacularly) in 2005.
Rijetka pojačana aktivnost se javlja kada Zemlja prođe kroz gušći sloj ostataka kometa; na primjer to se dogodilo 1998. i nešto slabije 2005.