At TFL, we're making journeys safer for everyone.

And that includes improving safety on London's roads.

That's why we and London boroughs are lowering more speed limits to 20mph.

Because 20mph roads have already reduced collisions resulting in deaths or serious injuries by 24%.

That is how we're making journeys in London safer and brighter for everyone.

Such TFL improvement plan to the Mayor of London and TFL every journey matters.

This is CBS. I am the world. I'm John Batcheson. Hotel Mars Episode N, a comet in the sky.

Our forebears believe that comets were associated with the birth of kings, the death of kings

or catastrophe. And they could prove it each time. Here we are in the 21st century.

And comets are associated with learning more and more about the makeup of our solar system,

the primary elements. Comets appear to be part of our world and then yet they pass us by.

What can we learn from them? David Livingston, my colleague in co-host,

co-pilot of hotel Mars. And we invite the President of Earthrise Institute,

former Adjunct Professor at American Public University System. Alan Hale. Alan is our guide on

comets. He is one Hale part of the very famous Hale Bob comet. But this comet we're talking about

is in the sky right now. It's called Comet ZTF. Alan, a very good evening to you. Thank you for

this. Before we get to ZTF and its lore, what is a comet? How is it distinguished from an asteroid?

We keep sending probes to asteroids and we're led to believe that comets are special. How so?

Good evening to you. Actually, the difference between comets and asteroid is very

interesting question. It's no easy answer, but that starts to get a little complex. But both comets

and asteroids are leftovers from the formation of the solar system four and a half billion years

ago. Asteroids are more rocky in terms of their composition, whereas comets are more volatile.

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