The ground beneath your feet feels completely still... but the continents are actually moving all the time.

In this episode of Why Though?, Dr Matt Agnew explains why continents drift across the Earth, how tectonic plates slowly carry them around the planet, and how that movement creates mountains, deep ocean trenches and earthquakes.

What you'll discover:

• Continents move just a few centimetres each year... about as fast as your fingernails grow
• Long ago, every continent was joined together in one giant supercontinent called Pangaea
• Earth's crust is made of enormous tectonic plates rather than one solid shell
• When plates collide they can push up mountain ranges like the Himalayas
• When one plate slides underneath another, it creates deep ocean trenches through a process called subduction
• Earthquakes happen when pressure builds between stuck plates before suddenly being released

Why Though? The show for little scientists who love asking big questions. Subscribe so you never miss an episode.

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It looks like magic. It makes spooky fog that pours down instead of floating up. And it never leaves a puddle. So what is dry ice actually doing?

Dr Matt Agnew unpacks the weird science of dry ice, what sublimation is, why the fog pours downward like a waterfall, and why dry ice behaves so completely differently from the ice in your freezer.

What you'll learn:

• Normal ice is frozen water... dry ice is frozen carbon dioxide, the gas we breathe out
• Dry ice skips the liquid step entirely... straight from solid to gas with no puddle
• Scientists call that process sublimation, one of the most interesting phase changes in science
• The fog is mostly not carbon dioxide at all... it's water vapour from the surrounding air getting chilled so fast it becomes visible
• Cold air and carbon dioxide are both heavier than regular warm air, so the fog pours downward like a fog waterfall
• Dry ice is essentially a natural fog machine used in theatres, film sets and Halloween displays worldwide

Key Science Ideas:

• Sublimation: When a solid skips the liquid stage and goes straight to gas
• Carbon dioxide: The gas we breathe out, and what dry ice is made of
• Water vapour: Invisible water in the air that becomes visible when it gets suddenly cold
• Phase change: When matter moves between solid, liquid and gas states
• Density: Why cold air and carbon dioxide both sink rather than rise

Safety note: Dry ice is extremely cold and must only be handled by adults wearing insulated gloves. It should only be used in well ventilated spaces. This is a watch and learn episode.

Why Though? The show for little scientists who love asking big questions. Follow or subscribe so you never miss an episode.

Follow Dr Matt Agnew:

Instagram: instagram.com/drmattagnew

TikTok: tiktok.com/@drmattagnew

YouTube: youtube.com/@whythoughpod

Website: drmattagnew.com

Find Why Though? podcast across the internet and share with your friends!

Instagram: instagram.com/whythoughpod

TikTok: tiktok.com/@whythoughpod

Facebook: facebook.com/whythoughpod

Hosted on Acast. See acast.com/privacy for more information.

A cheetah? A race car? A rocket? All great guesses. All completely wrong. The fastest thing on Earth is something you can't hold in your hand... and understanding it means understanding lightyears, the speed of light, and why space distances break normal numbers.

Dr Matt Agnew runs the ultimate speed race from Usain Bolt all the way to the speed of light, and explains what a lightyear actually is along the way. Spoiler... most adults get it wrong.

What you'll learn:

• Usain Bolt tops out at around 44 kilometres per hour... the slowest in this race by a long way
• A cheetah sprints at 100 to 120 kilometres per hour... basically a furry rocket
• An F1 car reaches around 350 kilometres per hour... blink and it's gone
• NASA's Parker Solar Probe is the fastest human-made object at 690,000 kilometres per hour
• Light travels so fast it feels instant... and in one second it can circle the entire Earth about seven times
• A lightyear isn't time, it's distance... how far light travels in one whole year, about 9.5 trillion kilometres
• The closest star to Earth after our Sun is Proxima Centauri, just 4.2 lightyears away

Key Science Ideas:

• Speed of light: About 300,000 kilometres per second... the ultimate speed limit of the universe
• Lightyear: A unit of distance, not time... how far light travels in one whole year
• Proxima Centauri: The closest star to Earth after our Sun, 4.2 lightyears away
• Parker Solar Probe: NASA's spacecraft and the fastest human-made object ever built
• Astronomical scale: Why scientists need special units like lightyears to measure enormous distances in space

Fun Experiment: The Lightyear Myth Buster

Ask three people in your house or school what a lightyear is. Most will say it's a unit of time. They're wrong... it's distance. Explain that a lightyear is how far light travels in one year, about 9.5 trillion kilometres. You've just done your first myth-busting science experiment, and you didn't need a single piece of equipment.

Why Though? The show for little scientists who love asking big questions. Follow or subscribe so you never miss an episode.

Why Though? The show for little scientists who love asking big questions. Follow or subscribe so you never miss an episode.

Follow Dr Matt Agnew:

Instagram: instagram.com/drmattagnew

TikTok: tiktok.com/@drmattagnew

YouTube: youtube.com/@whythoughpod

Website: drmattagnew.com

Find Why Though? podcast across the internet and share with your friends!

Instagram: instagram.com/whythoughpod

TikTok: tiktok.com/@whythoughpod

Facebook: facebook.com/whythoughpod

Hosted on Acast. See acast.com/privacy for more information.