merry dancers

plural plural-only

Beams of the northern lights when they rise and fall alternately without any considerable change of length.

Japanese Meaning

北極光が、光線の長さに大きな変化を伴うことなく、交互に上昇・下降する際に見られる光の帯

We stood in silence watching the merry dancers flare and subside across the Arctic sky.

私たちは黙って立ち、長さがほとんど変わらずに交互に上下するオーロラの光の筋が北の空に揺れ動くのを見つめた。

Sense（1）

Beams of the northern lights when they rise and fall alternately without any considerable change of length.