Space has always been a source of fear and fascination for humankind. The secrets it

hides and its celestial objects that look like shooting stars mesmerize and intrigue

people. However, even modern technology can't save us from occasional confusion. Asteroids,

meteoroids, comets... What's the difference between these space phenomena? And which of

them can be the most threatening to our planet?

We'll tell you a bit later about the methods scientists invented to protect Earth if a

massive celestial object decides to pay us a visit. But first of all, let's figure out

the differences between the main space travelers: asteroids, meteoroids, and comets.

Comets are solar system bodies that consist mostly of ice. When they approach the sun,

comets leave a trail of ice, rock particles, and dust. They typically appear in the outer

solar system.

Asteroids are sometimes classified as minor planets. This means that their size is pretty

impressive, and they orbit the sun. What is more, some of them even have moons of their

own.

As for meteoroids, they are much smaller than asteroids and can be as tiny as sand particles.

They are, in fact, debris drifting in space in orbit around different celestial bodies.

Their speed is higher than that of asteroids, and they can consist of various materials,

from ice to iron.

To avoid further confusion, we should also distinguish between meteoroids, meteors, and

meteorites. Once again, meteoroids orbit the sun. However, if they break through the atmosphere

of our planet, they begin to burn (that's when they start to look like shooting stars).

At this moment, they change their name to meteors. Only after they survive this plummeting

descent and hit the surface of the planet are they called meteorites. A study in 1985

suggested that a human being would be hit by a meteorite every 180 years.

Another interesting thing connected to meteors is meteor showers, during which a lot of meteors

can be seen in the sky in a short period of time. The most famous meteor shower happened

in 1833 when more than 10,000 meteors were seen every hour. This means that about 15

meteors were noticed every second! This meteor shower was named the Leonid meteor shower.

Meteorites make the planet 110,000 tons heavier every year, according to the estimations of

scientists. The Planetary Science Institute states that more than 500 meteorites reach

the surface of the planet yearly, but only 10 or fewer are ever recovered. The main reason

is that these space objects mostly fall into the oceans and seas.

The largest meteorite known to people is the Hoba meteor, situated in Namibia, Africa.

It was first spotted by a local farmer in 1920. This huge object most likely survived

thanks to its content: mostly iron and 16% nickel. It measures 9 ft by 9 ft by 3 ft.

As for its weight, it's a whopping 66 tons.

In any case, however big and fast meteorites are, they can't cause the same damage that

Earth can experience if an asteroid were to hit. And there is evidence of what happens

when a stray asteroid crashes into the planet.

The asteroid belt between Jupiter and Mars is home to many asteroids. However, from time

to time, they leave their orbit and move closer to Earth. Luckily, we haven't had any huge

asteroids hit Earth in the past several thousand years, but it has happened.

The most famous crater left after the impact of an asteroid is probably the Arizona Meteor

Crater, which appeared more than 50,000 years ago. This impact crater is about 1 mile in

diameter and has a depth of 560 ft.

That's not the only impact crater we know about. There are approximately 180 documented

sites. Some of them are enormous! For example, Vredefort Crater in South Africa has a radius

of 118 miles. It's the largest known impact site on our planet.

Most people believe that the asteroid that fell near the coast of the Yucatan Peninsula

in Mexico caused the most disastrous impact in the history of Earth. The asteroid raised

such a huge cloud of dust that it completely changed the climate of the planet. According

to scientists, this celestial object was to blame for the extinction of dinosaurs about

65 million years ago.

However, our planet had a much more serious encounter 3 billion years ago. An asteroid

that fell to Earth was even bigger than the one that killed the dinosaurs. In addition,

its speed was extraordinarily fast: more than 12 miles per second! Scientists think that

this asteroid fell somewhere in South Africa, and this led to the changes in the tectonic

structure of the planet.

Nowadays, with the development of modern technologies, asteroids don't present such a terrible threat.

Every year, according to NASA specialists, an asteroid as big as a car enters Earth’s

atmosphere, turns into a spectacular fireball, and disintegrates before it has a chance to

reach the surface of the planet. On the other hand, a celestial object as large as a football

field hits Earth every 5,000 years, causing serious damage. Once every several million

years, our planet collides with a space body so large that it causes a global planetary

catastrophe.

As you can see, such an encounter can turn our peaceful life into a disaster movie. Therefore,

a question arises: is it possible to stop an asteroid that threatens life on Earth?

The answer is yes. In fact, there are 3 solutions.

1. ARM (Asteroid Redirect Mission)

NASA is currently working on creating the first robotic mission. This mission will be

connected with the potential threat that asteroids present to our planet.

The first task of the robotic mission will be to approach a large asteroid located close

to Earth, collect a multi-ton rock from its surface, and redirect the asteroid to a stable

orbit around the moon.

This will serve a double purpose. First of all, specialists will gain experience in removing

a potential threat to our planet. Secondly, astronauts will return with a sample of an

asteroid in the 2020s.

2. DART (Double Asteroid Redirection Test)

The DART mission will be the first demonstration to see if people can use the kinetic impact

technique to make an asteroid change its course in space.

Scientists have already chosen the target: it will be the binary asteroid 65803 Didymos.

This space body will be spotted close to Earth in October 2022, passing just 620,000 miles

away. The DART mission will impact the asteroid's secondary body, crashing into it at a speed

of 4 miles per second. If everything goes as planned, this collision will change the

course of the moonlet around the primary body by a fraction of 1%.

Such a small number may seem like nothing, but it can make a huge difference when moving

the course of an asteroid hundreds of miles away from our planet.

3. DE-STAR mission

DE-STAR (Directed Energy System for Targeting of Asteroids and exploRation) sounds like

something from science fiction!

Such a system could potentially destroy asteroids, comets, and other dangerous near-Earth space

bodies that pose a high risk of impact. If DE-STAR were created, it would consist of

satellites that would gather solar energy and convert it into an array of such powerful

lasers that they would be able to disintegrate an asteroid.

At the moment, this system is still theoretical. However, some scientists state that the technology

to make the idea of the super-laser come true already exists. People just need to construct

a DE-STAR model big enough (perhaps as big as 6 miles across).

Oh, have you already pictured a laser blast scattering asteroids? Sorry to disappoint

you, but DE-STAR (with a diameter of 328 ft) would just slowly push asteroids and comets

out of their orbits and away from Earth. As for a large-scale DE-STAR system (say, 6 miles

in diameter), it could potentially destroy an asteroid with a diameter of 1,700 ft, but

this process would take approximately one year.

In any case, whatever solution scientists choose, Earth won't helplessly wait for a

huge asteroid to crash into its surface.

Do you believe in the possibility of a celestial body coming into contact with our planet and

causing a natural disaster? Tell us in the comments below!

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