I'm not sure if it is modern or not but the earlier skiers used either a spear or long pole.
Back then it was easier for early skiers to remember to bring them because they only used one long pole.
im planning a Skiing trip next winter That's cool, are you going to go skiing for a competition or as a means of transport or something else? no, i just do it for fun. anything i should know  in advanced for my Skiing trip? Not about your trip but you may be interested to know that the first skier with two ski poles was depicted way back in 1741. Oh no way? I would have though two poles is a modern thing.
Early skiers used one long pole or spear.