Ben and Zoe watched, mesmerised, as long shimmering curtains of light wove their way through the dark sky. The colours swirled and flashed above their heads.
Zoe clutched Ben’s arm. “What’s happening?” she breathed. “It’s so weird!”
To her surprise he was grinning from ear to ear. “Don’t be scared. It’s the aurora borealis.”
“The northern lights!” cried Zoe. “Of course! This is awesome! I’ve always wanted to see them – but I never thought they’d be like this.”
They gazed up as luminous yellow ribbons danced across the sky, followed by waving beams of red and green. At times the children could almost see giant faces and shapes in the billowing colours.
“Now I can see why there are stories about them being gods in the sky,” murmured Zoe.
“They’re actually caused by particles from the sun colliding with the oxygen and nitrogen atoms in the atmosphere,” Ben told her.
“Thanks, Mr Walking Encyclopaedia,” joked Zoe. Then she caught her breath. “I think I know why our BUGs stopped working,” she said thoughtfully. “It must be all this electrical activity.” She scanned the area. “But look how well it’s lighting up the terrain.”
“You’re right,” said Ben, pointing eagerly. “I didn’t see that tall bank of snow ahead.”
Zoe nodded. “Could be the very place for a polar bear den.”
They jumped on to their RATs and set off for the snow bank, which shimmered with the reflected glow from above.
“Thank you, northern lights,” Zoe yelled up at the sky. “We can see really well now. It could be day. Sorry we haven’t got time to watch the whole show.”
They skidded to a stop where the bank began, sending up a shower of snow.
“It’s much bigger than I thought,” said Ben. He looked up and down the long ridge through his thermogoggles. “It’ll take hours to search this lot.”
“Got an idea,” said Zoe. “If it’s the weird electricity of the aurora borealis that’s interfering with the BUGs then it might only be their satellite function that’s affected.” She held her BUG out in triumph. “I was right,” she said. “Look, the scent disperser’s OK and the animal cry analysis.”
“Great, then we can set that to pick up the cubs’ call,” said Ben. “It has a much wider range than the thermogoggles.”
“The lights are getting fainter,” said Zoe, looking up to see a fading red glow in the distance. “It’ll be dark again soon. We must search as quickly as we can while there’s still some extra light.”
They moved along the bank, scanning every centimetre of snow with the goggles and checking their BUGs for an indication that the cubs were nearby. But the glow in the sky was fast disappearing, and soon they were relying on their headlamps and the pale moonlight to find their way.
Zoe stopped and held up her BUG. It was flashing. “Polar bear cub cry,” she read excitedly.
“Where’s it coming from?” said Ben.
“That’s strange,” said Zoe, frowning. “It can’t be coming from a den. The cry’s well away from the bank.” She spun round and pointed at a jagged point of ice that rose up from the snow. “Behind there, I think.”
Ben set off quickly, his boots sending up sprays of snow as he ran.
“Slow down,” warned Zoe. “You don’t want to scare it.”
As they rounded the point of ice, Zoe saw something in the beam from her headlamp.
It was a tiny bear cub.