Astronomer Philip Plait — who fell in love with Saturn after first viewing the gas giant, with its mesmerizing rings and moons, through a telescope as a child — shares some of the amazing discoveries we've made about the planet in recent years. Then actor Martin Sheen describes how his travels in the developing world have opened his eyes, and his heart, to the needs of others. And a Florence-based tour guide and culinary expert lets us in on where to find the best food in her adopted home.

An Easter Island-based travel writer and lecturer lets us in on what life is like on the cruise-ship circuit. Then journalist Lyse Doucet recounts her career as the BBC's chief international correspondent and delves into the issues her profession grapples with today.

Bradt guidebook author Joshua Zukas, who focuses exclusively on Vietnam, shares why he enjoys challenging misconceptions about his adopted home. And a writer who has spent his life captivated by the mighty Mississippi River takes us on a virtual tour of America's great waterway, from Minnesota to the Gulf of Mexico.

One of Rick's tour guides opens our eyes to the idyllic "Swiss Riviera" that borders Lake Geneva. Then a British journalist and safari expert takes us into Africa, sharing the best ways to find authentic safari experiences. And a hiking-and-biking tour operator tells us how to escape the crowds of Europe's grand cities by spending a few days hitting the trail.

Find out why Germany's "second city," the industrial northern port of Hamburg, is a first-choice getaway for many of the country's residents. Then get the inside scoop on Rick's "Art of Europe" TV miniseries, which explores the backstories of the continent's greatest artworks. And consider what drives some death-defying athletes to go all-in for "extreme sports."

Two Dutch tour guides help us get the picture on what's new on Amsterdam's eclectic exhibit scene. Then a Blue Badge guide lets us in on where to go in London to see the exciting ways the venerable city is reinventing itself. And a journalist delves into the inexact science of borders and ponders the complicated relationship between physical geography and national identity.

A budget-minded travel blogger shares timely tips for keeping costs down — so that you can keep your travel dreams alive. Then a British journalist with a passion for rail travel enthuses about the special magic of the sleeper train. And an American writer based in Chile tells us what he loves about living in South America.

Celebrate Norwegian roots in America as we mark the 200th anniversary of a major wave of immigration to the US from the Scandinavian nation. Then join an expert of the offbeat as he delves into some of the more curious places and things held dear by people around the world. And listen in as callers share their favorite travel memories of the year behind us. Plus, learn from Scottish tour guides about Edinburgh's lively New Year's Eve traditions of Hogmanay.

Christmas is a little different across the pond — where Santas dwell on farms or in the woods, festively decorated boats stand in for sleighs, and fermented trout is a must-try treat. Learn about holiday traditions observed in France, Norway, Greece, London, the Spanish Basque Country, and small-town Italy, as a slate of Rick's guides share their customs and memories of this festive season.

Hear a Francophile's recommendations for some of the most magnificent religious architecture to explore in Paris. Then vicariously experience a winter solstice ritual from inside an ancient tomb in Ireland, and warm up to the custom that's central to life in Finland: the sauna. Plus, kick off the Christmas season with local holiday traditions from Tallinn, Rome, and Venice.