Billions of viruses are raining down on you from the upper atmosphere every day
![](https://i.cbc.ca/1.4954465.1545332136!/fileImage/httpImage/image.jpg_gen/derivatives/16x9_780/germany-weather.jpg)
The next time you go outside and take a deep breath of fresh air, think about this: as you stare up into the sky, billions of tiny invisible viruses are raining down on you.
![](https://i.cbc.ca/1.4951522.1545169240!/fileImage/httpImage/image.jpg_gen/derivatives/original_780/picture2-dpi-300-jpg.jpg)
Lab grown lungs are transplanted in pigs today, they may help humans tomorrow
![](https://i.cbc.ca/1.4951380.1546269997!/fileImage/httpImage/picture1-dpi-300-jpg.jpg)
Lab grown lungs are transplanted in pigs today, they may help humans tomorrow
![](https://i.cbc.ca/1.4759866.1532459233!/fileImage/httpImage/image.jpg_gen/derivatives/16x9_620/the-best-earth-based-view-of-mars-ever.jpg)
Dec. 29, 2018 — Water on Mars, lab-grown lungs and more: The biggest science stories of 2018
![](https://i.cbc.ca/1.4951360.1545169738!/fileImage/httpImage/image.jpg_gen/derivatives/16x9_780/bioengineered-lung.jpg)
Lab grown lungs are transplanted in pigs today, they may help humans tomorrow
![](https://i.cbc.ca/1.4955925.1552578265!/fileImage/httpImage/britain-culture.jpg)
Even kids as young as four want to punish freeloaders
![](https://i.cbc.ca/1.5479612.1582931315!/fileImage/httpImage/image.jpg_gen/derivatives/original_620/radar-truck.jpg)
We've been cloud seeding for decades, but now we finally know it works
![](https://i.cbc.ca/1.4667468.1681241786!/fileImage/httpImage/tiny-garden.jpg)
Even kids as young as four want to punish freeloaders
![](https://i.cbc.ca/1.4847670.1538509053!/fileImage/httpImage/image.jpg_gen/derivatives/original_780/exomoon-kepler-1625b.jpg)
Dec. 29, 2018 — Water on Mars, lab-grown lungs and more: The biggest science stories of 2018
![](https://i.cbc.ca/1.4954465.1545332136!/fileImage/httpImage/image.jpg_gen/derivatives/16x9_780/germany-weather.jpg)
Billions of viruses are raining down on you from the upper atmosphere every day
![](https://i.cbc.ca/1.4824344.1536957783!/cpImage/httpImage/image.jpg_gen/derivatives/original_780/tropical-weather-north-carolina.jpg)
Dec. 29, 2018 — Water on Mars, lab-grown lungs and more: The biggest science stories of 2018
![](https://i.cbc.ca/1.4954211.1613083719!/fileImage/httpImage/image.jpg_gen/derivatives/original_780/mars-express-in-orbit-around-mars.jpg)
A lake of water was found on Mars — and may be the first of many
![](https://i.cbc.ca/1.3199665.1517961534!/fileImage/httpImage/image.jpg_gen/derivatives/original_780/china.jpg)
Dec. 29, 2018 — Water on Mars, lab-grown lungs and more: The biggest science stories of 2018
![](https://thumbnails.cbc.ca/maven_legacy/thumbnails/27/331/Quirks-640x360.jpg)
We've been cloud seeding for decades, but now we finally know it works
![](https://i.cbc.ca/1.4950606.1545147895!/fileImage/httpImage/tess.jpg)
TESS, the planet hunting space telescope, is on track to discover a sky full of exoplanets
![](https://i.cbc.ca/1.4954841.1545337963!/fileImage/httpImage/afp-17y9gl.jpg)
The year in climate change: Fires and heat-waves show things are heating up