Author: BBC World Service

This week we turn our gaze skywards to tackle three questions about what’s going on above us. Three year old Zac from the UK wants to know what clouds feel like – if they’re supposedly like steam, then how are they cold? Presenter Graihagh Jackson meets a meteorologist who can not only tell us but show us the answer, as we attempt to make a tiny cloud at ground level in the studio. Listener Agnese is looking beyond the cloud base and up to our nearest neighbour. She’d like to know why it is that we can see the Moon during the day. And Graihagh heads out to one of the longest-running and largest steerable telescopes in the world: The 76-metre Lovell Telescope at Jodrell Bank Observatory in the UK. Here, she finds out the answer to Sandeep from India’s extra-terrestrial question: Could aliens find us?

(Image: Clouds in a blue sky. Credit: Getty Images)

The size of brains in the animal kingdom is wildly different, from melon-sized in blue whales to pea-sized in shrews. But does a bigger brain mean a more powerful one? CrowdScience listener Bob wondered just this as he watched various sized dogs running amok in his local park: the Great Dane has a much larger brain than a Chihuahua’s, yet the job of ‘being a dog’ surely requires the same brain power. So why have a big brain if a small one would do? A search for the answer takes Geoff Marsh to dog agility trials, behind the scenes at London’s Natural History Museum and a laboratory that studies bumble bees. It turns out that size does matter, but not in the way you might think. Presenter: Geoff Marsh Producer: Dom Byrne

(Photo: Great Dane HARLEQUIN and a chihuahua Getty Images)

Our species started in Africa, but what was the last habitable landmass we reached? CrowdScience presenters Marnie Chesterton and Geoff Marsh team up to investigate how and when our species journeyed around the world and settled its most far flung landmasses. Geoff heads to some ancient caves in Israel to investigate the ‘false starts’ humans made out of Africa, and Marnie speaks with Professor Lisa Matisoo-Smith in New Zealand, uncovering the development of Polynesian sailing canoes and how they enabled the last landmasses to be found by people. This is a story spanning over seventy thousand years, huge changes in culture and technology, and the repeated remodelling of the earth thanks to the ice ages.

Produced by Rory Galloway

(Photo: Polynesian canoeists at sunset. Credit: Richmatts/Getty Images)

It’s the sort of plot you would expect from a classic sci-fi movie; what if there are viruses trapped deep in Antarctic ice that could wreak havoc on humans?

Crowdscience presenter Alex Lathbridge puts on warm gloves and meets the scientists venturing into the icy wilds. He wants to answer listener Tony’s question - can viral life exist in such inhospitable climes and if so, might it pose us a danger?

Alex meets teams who venture to the Antarctic to find out about how their work to understand climate change leads them to drilling and analysing ice cores that are tens of thousands of years old. He then visits a dynamic husband and wife duo in France who are extracting viruses from 30,000 year old Siberian permafrost and bringing them back to life. He discovers that - rather than killing us all, - their findings of novel giant viruses might contribute to medicine and our understanding of evolution.

(Photo: Scientists working in a laboratory. Credit: Getty Images)

Waste, trash, garbage – whatever you call it, unwanted materials have become a major presence in many of our lives and our environment. Every year it is estimated that humans around the world produce 2 billion metric tonnes of waste. Listener Clare from Devon in the UK wants to start tackling this herself. She would like to know if she can not just sort but process all her own recycling at home.

Presenter Marnie Chesterton attempts to find out by asking the professionals. She heads out to an industrial-scale recycling plant to see if any of their gear could work in our homes, hears from reporter Chhavi Sachdev how waste collectors in Mumbai, India have to balance thrift with risk, and asks environmental engineer Jenna Jambeck whether she thinks solely domestic recycling is possible.

(Image: Garbage bags with various bits of recycling, iron, paper and plastic. Credit: Getty Images)

The ritual of burying the dead stretches back to the obscure beginnings of human history - and perhaps beyond, with archaeologists uncovering evidence of burials that pre-date our own species. But why do we bury our dead? How important is it, and how did the practice evolve? CrowdScience listener Moses from Uganda began pondering these questions after attending a close relative’s funeral.

We search for clues in some of the earliest known burial sites, compare other methods for dealing with human remains, and explore how the funeral practices around the world today compare to those of our ancestors. Did these rituals originally develop for reasons of simple hygiene, or are religious and symbolic aspects the real key to understanding them?

Presented by Anand Jagatia Produced by Cathy Edwards for the BBC World Service

(Photo: A bereaved young woman in black, taking flowers to a grave. Credit: Getty Images)

When CrowdScience listener, Grady, crashed violently on his motorbike in the desert, he thought he was going to die. Years later he still can’t remember the dramatic seconds just before the impact. Where did the memory disappear to? Did the hard hit to the head knock his memories out or are they still in his brain somewhere? CrowdScience turns to brain science to find out if those last few seconds are lost for good or if the brain tells a different story.

Under normal circumstances our brains like to hold onto memories that are emotionally important to us. We can remember our wedding day but not yesterday’s breakfast. But scientists have discovered that during near-death experiences, our brains are flooded with chemicals that disrupt our ability to remember. Grady may never recall how he was able to keep his motorbike steady as he drove off the road because – maybe – the memory was never created in the first place.

Presenter: Marnie Chesterton Producers: Melanie Brown and Louisa Field Sound design: Eleni Hassabis

(Image: A biker helmet lies on street near to a motorcycle accident. Credit: Getty Images)

Magma is the hot, molten rock found beneath the Earth’s crust. It’s so plentiful that it got Greek listener Dimitrios wondering whether we could harness this heat. Could we drill directly into the magma and use it to power our homes, he asks presenter Marnie Chesterton? And from Ghana, Madock also got in touch with CrowdScience to ask why there are lots of volcanoes in some areas of the world, but then none in others?

Marnie dispatches Anand Jagatia to Kenya, a country that is one of the biggest providers of geothermal energy in the world and home to the East African Rift system. At 4,000 miles long, a string of volcanoes sits along this fault line. Anand hikes up one of these to find out why volcanism is so active here. Anand then travels to a geothermal power plant to get to grips with how conventional geothermal energy works, before turning to Iceland, where they’ve drilled directly into magma - albeit by accident. What they discovered was supercritical steam. It’s neither a liquid nor a gas but holds up to 10 times more energy than both. And to find it naturally occurring is the ‘holy grail’ of geothermal power. But can our equipment stand such temperatures?

Presenter: Anand Jagatia and Marnie Chesterton Producer: Graihagh Jackson

(Image: A volcano erupts. Credit Getty Images)