Analog Science Fiction and Fact, December 2009

• Serial (2 of 2): To Climb a Flat Mountain, by G. David Nordley - The castaways on Cubeworld climb to another face of the world, locate a shuttle from their wrecked spaceship, and eventually contact the builders of Cubeworld.
• Novelette: Formidable Caress, by Stephen Baxter - On old Earth where time is stratified, one man moved down to the slow lands so he can live long enough to see the Formidable Caress--the collision between the Milky Way and another galaxy.
• Novelette: Wilderness Were Paradise Enow, by H. G. Stratmann - Two very stupid humans land on Mars, where they meet aliens who give them superpowers. It's all a test to see if mankind is fit to continue living, and they fail the test because the women tricks the man and doesn't let him attempt to solve the world's problems.
• Short story: The Jolly Old Boyfriend, by Jerry Oltion - An old boyfriend shows up on Christmas Eve, which wouldn't be unusual except that 1) he's dead, 2) he's dressed as Santa Claus, and 3) he's slightly transparent.
• Short story: The Universe Beneath Our Feet, by Carl Frederick - Buoyant aliens live on the underside of the ice, and religious disagreements about what lies 'below' the ice threaten to break the community apart.
• Short-short: A Flash Of Lightning, by Robert Scherrer - A teacher explains to his class that when the friction of the timeline causes large changes to be progressively dampened until they eventually result in negligible changes, this is called the Butterfly Effect.
• Science Fact: Plate Tectonics, Goldilocks, And The Late Heavy Bombardment: Why Earth Isn't Mars Or Venus, by Richard A. Lovett - Plate tectonics help keep Earth's atmosphere regulated so it doesn't get too hot or too cold.