It may seem like a simple question but could you explain why the earth revolves around the sun? That’s what listener Josh from New York wants to know. For much of human history we thought everything revolved around us, literally. So how did humans come to the conclusion that we're not the center of the universe? And how did the scientific process help us uncover the true order of things? Looking through telescopes from the vantage point of Australia, host Caroline Steel speaks with astronomers and physicists about the bumpy scientific journey to arrive at this discovery that we now take for granted. Delving into Indigenous astronomy with researcher Peter Swanton, Caroline questions whether Western scientists were really the first ones to grasp this understanding of our solar system. And at the Sydney Observatory, stellar astrophysicist Devika Kamath and Sydney Observatory host Nada Salama show Caroline some of the clues up in the sky that astronomers in the 1600s used to deduce that there was something wrong with earlier models of our solar system. Rhett Allain from Southeastern Louisiana University helps break down the physics concepts at play when it comes to the motion of our planets and the sun. Through her exploration of a seemingly simple question, Caroline asks some big questions as she looks up to the stars – about life, the universe, and the nature of science itself. Produced by Sam Baker for the BBC World Service Presenter: Caroline Steel Editor: Richard Collings Production Coordinator: Jonathan Harris Featuring: Devika Kamath, Astrophysicist, Macquarie University Rhett Allain, Associate Professor, Southeastern Louisiana University Peter Swanton, Indigenous Research Associate, Australian National University (Photo: Caroline and Devika Sydney Observatory)

Anyone who has ever enjoyed a beach holiday will know there’s something special about being by the seaside. But does sea swimming actually have tangible health effects? This week’s listener Holly is a self-confessed water baby, and says her regular surf sessions on Sydney’s iconic Bondi beach make her feel happier and look younger. But could we get some of the benefits from the beach without getting our feet wet? At the Plymouth Marine Lab, researchers have shown that the smell of the sea makes most people feel happier. They’re measuring sea spray aerosols containing natural compounds derived from algae, that dial down the inflammatory response in lung cancer cells. Other scientists in the region have investigated the use of virtual reality to simulate being by the coast, which is proven to reduce the experience of dental pain during treatment. Finally, we visit Teats Hill in Plymouth to find out how a waterside amphitheatre and an urban beach are helping residents feel safer and more connected to one another. Producer: Marijke Peters Presenter: Marnie Chesterton Editor: Richard Collings Production Coordinator: Jonathan Harris Contributors: Dr Frances Hopkins, Plymouth Marine Laboratory Dr Mike Moore, Plymouth Marine Laboratory Dr Mathew White, University of Vienna Dr Easkey Britton Image credit: David Sacks | The Image Bank | Getty Images | 164241179 Created for the #BBCWorldService.

Lazy. Unmotivated. Procrastinating. If those are words you’re used to hearing from your inner critic, you are not alone. Take CrowdScience listener Laurie. On her days off she loves to relax on the sofa, watch TV, put off chores and generally do as little as possible. Meanwhile she sees other family members and colleagues apparently buzzing with energy: going the extra mile at work, taking up hobbies, going to the gym. Why, she asks, is she so lazy? CrowdScience turns to experts to find out whether or not so-called ‘laziness’ is a fundamental part of biology or psychology; why some people have more energy than others; and we offer a few tips for boosting energy and motivation. Or maybe Laurie is just being a bit too hard on herself? With psychologists Professor Fuschia Sirois and Dr Devon Price, anthropologist Professor Herman Pontzer and start-up entrepreneur Akhil Aryan. Presented by Dr Alex Lathbridge Produced by Cathy Edwards for the BBC World Service Editor: Richard Collings Production Co-ordinator: Jonathan Harris Studio Manager: Jackie Margerum Image: Asleep under a book (Credit: RichVintage via Getty Images)

Meet the ostrich, one of nature’s most unusual creatures: a two-metre-tall, flightless bird that struts about the African savannah. CrowdScience listener Pat found herself entranced by seeing them on a wildlife documentary, where two ostriches were exhibiting some bizarre behaviour. According to her, the female was sitting on her eggs in a ‘nest’ that was barely a dent in the ground, while the male was just flapping his feathers around her. So Pat came to us to ask: what are ostriches for? Anand Jagatia starts by meeting one face-to-face at Woburn Safari Park. Tom Robson, Head of Reserves at the park, gives Anand a tour of ostriches’ unique features. He discusses their status as the largest and fastest birds in the world and explains the unusual mating behaviour Pat observed on the TV programme she was watching. Next, to answer why some of these traits exist, Peter Houde from New Mexico State University dives into the ancient fossils. Peter is one of the palaeontologists who has managed to uncover the secrets of ostrich origins. What did their ancestors look like -- and why did they lose the ability to fly? Ostriches are also a part of human culture. Their eggs, for example, have been objects of value for thousands of years. Archaeologist Tamar Hodos from the University of Bristol explains how decorated ostrich eggs have been uncovered from ancient tombs and how they were probably used as pouring vessels as well as status symbols. Anand receives an ostrich egg in the post and manages to cook it using a very specific and British process. Finally, designer Pascale Theron tells us about the history of the ostrich farming industry. It’s a classic rags-to-riches-to-rags tale, a manic boom at the start of the 20th Century all based around feathers that were worth their weight in gold. Presenter: Anand Jagatia Producer: Phil Sansom Editor: Richard Collings Production Co-ordinator: Jonathan Harris Image credit: Phil Sansom & Anand Jagatia

Inside our gut lives an entire ecosystem of bacteria and microbes, called the microbiome. In fact, the human body contains trillions of microorganisms, which outnumber our cells by ten to one. This means that technically we are more microbe than human. But not only do these microbes rely on us to survive, we also rely on them for some vital bodily functions. So what impact do these trillions of microbes have on our health? That’s the question that’s been bothering CrowdScience listener Russell, from Canada. Presenter Caroline Steel investigates. She visits the only museum in the world dedicated to microbes to ask exactly what they are, what they do and why we have so many of them inside our bodies. And she visits a microbiology lab filled with model guts to find out what impact the microbiome has on our physical health and if there is anything we can do to help our microbes function better. Caroline finds out what impacts our microbiome, what we can do to improve our inner ecosystem, and how our microbes can take a disturbing turn on us after we die. Produced by Hannah Fisher and presented by Caroline Steel for the BBC World Service. Editor: Richard Collings Production Coordinator: Jonathan Harris Contributors: Professor Glenn Gibson – Professor of Microbiology, University of Reading Jasper Buikx – Microbiologist and Head of ARTIS Micropia David Good – Doctoral Candidate at the University of Guelph Image Credit: Microbiota of the human intestine/CHRISTOPH BURGSTEDT/SCIENCE PHOTO LIBRARY