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CARL AZUZ: On the Vernal Equinox, what's officially

the first day of spring in the Northern Hemisphere,

we're thankful you've set aside 10 minutes to watch "CNN 10."

I'm Carl Azuz at the CNN Center.

In the US Midwest, the north central part of the country,

there are states of emergency in Nebraska, Iowa, and Wisconsin.

Lots of rain plus melting snow plus a late winter snowstorm

brought by a bomb cyclone have left many places under water.

Part of the problem was that the ground was still

frozen when the rain came, and it wasn't

able to absorb the water.

So it found its way to rivers and streams

and caused them to burst their banks and spread water

all over.

On Tuesday morning, the National Weather

Service said more than 8 million people

were under flood warnings.

Nebraska was hit particularly hard.

Its governor said the flooding was

the most widespread disaster Nebraska had ever faced.

US Vice President Mike Pence traveled there

yesterday to survey the damage.

Nebraska's governor is hoping the federal government

will allow public funding to be used to help those affected.

In 17 places across the state, flood records were broken.

And in Iowa, 41 of the state's 99 counties

have been declared disaster areas.

In addition to at least four lives that

were lost in Nebraska and Iowa, farmers

have lost grain and livestock.

Fields are under water.

Private water supplies are threatened.

South of Nebraska and Iowa, the Missouri and Mississippi

rivers, which are already at minor or moderate flood stage,

are expected to rise higher in the next few days.

So states like Kansas, Missouri, and Illinois

could see more flooding in the days ahead.

In some places farther north, the water has begun to recede.

In others, the threat remains.

STEPHANIE ELAM: This is Winslow, Nebraska.

And for several days, the people who live here

in this small town of less than 200 people

couldn't even get in here to see what it looks like.

Now, they're able to clear away some

of the debris on the roadway.

But as you can see, look at the speed limit sign.

You can see how high the water still is, how high up

it is on these houses.

And every one of the houses in this town

are surrounded by water.

You could see, so many things have been pushed away,

toys, picnic benches, and even stairs

moved far away from the homes that they

used to stand next to.

Right now, while they're able to get closer, they still

cannot get into their homes.

And they don't know when they'll be able to because there's

still so much water in here.

And this is just one system where

the water is starting to recede, where

in others, it's still cresting.

So this is just a microcosm, a small picture

of what is happening throughout Nebraska

with these massive, devastating floods.

And I talked to one couple that has lived here

for several decades, over 30 years,

and asked them if they were going to rebuild.

And he said, we have nowhere else to go.

This is where we belong.

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- Whoa!

[SCREAMING]

[ALARM SOUNDING]

MICHAEL GARNETT: My entire apartment started shaking.

And there was a huge boom.

I was just terrified.

I had no idea what was happening.

CARL AZUZ: So if a meteor explodes

in the atmosphere and no one's around to hear it,

does it make a sound?

NASA says it did.

The fireball that blew up 16 miles over the Earth's surface

in December was the second most powerful one

to enter our atmosphere in 30 years,

according to the space agency.

So why wasn't this reported in December?

Because scientists just noticed it.

It was originally detected by military satellites

and reported to NASA afterward.

Why didn't pictures and video go viral on social media

like those of other fireballs do?

Because it happened over the Bering Sea

in a pretty remote part of the world.

And relatively few people noticed.

What exactly caused a blast that powerful?

A meteor that scientists say was probably a few meters across.

That's all it takes to release 173 kilotons of energy.

And for reference, one kiloton is equivalent to 1,000

pounds of TNT.

Should you be worried about another one?

Scientists say no.

Most fireball events are smaller.

There have already been five noteworthy explosions in 2019.

10 second trivia.

Where would you be most likely to find

mycelium, a mass of filaments?

In granite, on a CT scanner, on body armor, or in fungi?

The vegetative part of a fungus is called mycelium.

A growing number of artists, furniture

makers, and even clothiers are using mushrooms to make stuff.

And a big provider of the material for this

is a New-York-based company called Ecovative.

It's a bio-materials organization that's

received millions of dollars in grant money

from the US government, in addition to private funds

from private investors.

It's worked on everything from building

materials to packaging, all based

on using part of the mushroom.

When it comes to shipping materials,

it's not always the perfect substitute for Styrofoam

or other plastics.

Ecovative's original mycelium foam

could be more expensive to use than traditional materials

for lightweight packages.

But its makers say it is better for the environment.

And it's changing the way people think about mushrooms.

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- Since the 1950s, humans have produced

over 9 billion tons of plastic.

Most of that is ending up in landfills

and could take centuries to decompose.

A miracle material found in nature

could be the key to reducing plastic waste.

It's called mycelium, and it comes from mushrooms.

EBEN BAYER: Mycelium is like the root structure of a mushroom.

You're used to seeing a mushroom above ground.

Mycelium is like the roots beneath it.

But no one had ever tried to use them to make materials.

- Eben Bayer is the CEO of Ecovative, a company that

has developed a way to grow mycelium

into specific shapes and sizes.

They start by taking organic plant waste

and mixing it with mycelium cells, which

act as a sort of natural glue.

EBEN BAYER: The mycelium grows through

and around those particles.

And it binds them together.

And you've got a grown product.

- Ecovative's mycelium products provide a natural alternative

to packaging materials made out of plastic and Styrofoam.

EBEN BAYER: But at the end of its useful life,

you can actually break it up, and you could

put it in your own garden.

So it's a nutrient, not a pollutant.

- Ecovative wants to take mycelium to the next level.

EBEN BAYER: Our current technical focus

is developing the next generation of mycelium

materials, from cell scaffolding,

to leather-like materials, and even meat replacements.

- AKA, mycelium bacon, which is still in its testing phases.

The company thinks mycelium could also

play a major role in construction and even

in regenerative medicine.

EBEN BAYER: It really has boundless possibilities.

And it comes from its ability to move from the micro scale

to the macro scale.

CARL AZUZ: An astrolabe found off the coast of Oman

in the Middle East has just been awarded

the title of world's oldest by Guinness World Records.

An astrolabe is an instrument that

was used for centuries to mark the positions

of the sun and stars.

They were first used by astronomers hundreds

of years BC.

And sailors used them in the Middle Ages

until astrolabes were replaced by sextants.

Today, just over 100 mariners astrolabes are

known to exist in the world.

But add this one to the tally.

About five years ago, divers found it

at a shipwreck site near Oman.

Researchers believe it was made between 1496 and 1501.

And it's thought to have been used by Portuguese navigator,

Vasco da Gama, who was the first European

to sail from Europe to India.

The astrolabe had to be kept in a freshwater bath for two years

to get all the salt off it.

A symbol of Portugal's royal coat of arms

helped scientists identify it.

They hope its discovery will help them

understand more about how ships navigated

in the 14th and 15th centuries.

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Heliskiing, using helicopters to reach remote places to ski

has been around for decades.

As far as we know, Zeppelin skiing,

using an airship to get out in the back country,

is pretty new.

These three Austrian skiers worked

on the idea for almost two years before it

became reality in February.

They needed cold temperatures, clear skies, and no wind.

They also needed to descend by rope to the alpine summit

they intended to ski.

Was it worth it?

You'd better dirigibelieve it.

Of course, there were a few blimps in the road.

Their path to success wasn't always Zeppelinear.

And it took a while before everything

was an airship shape.

Big dreams often have steep slopes

and obstacles to traverse.

But once theirs got off the ground,

despite the ropes that repelled them,

they all clearly had a descent time.

I'm Carl Azuz.

And we'll ski you later on CNN.

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