One of the most well-known theories concerning the death of the dinosaurs argues that these
ancient creatures went extinct when a large stone from space slammed into Earth.
Through a series of events, this ultimately led to the extinction of dinosaurs.
You have probably heard countless stories and hypotheses regarding the disastrous consequences
of an asteroid strike on Earth, but what exactly are asteroids?
Where do they come from?
And most importantly, could they really obliterate the entire planet if they were to strike Earth
with enough force?
An asteroid is a small, rocky object that orbits the sun, just like the rest of the
planets and celestial bodies in our solar system.
Although asteroids are present throughout the solar system, most of them live in the
asteroid belt—a region located between the orbits of Mars and Jupiter.
The size of objects within the asteroid belt have a wide range, from being no bigger than
a dust particle to almost a thousand kilometers wide.
In fact, the largest asteroid present in the asteroid belt—Ceres—is 940 kilometers
wide and is considered a dwarf planet.
Although the asteroid belt hosts a multitude of asteroids, it’s not the only region where
these rocky objects hang around.
Some asteroids are also found in the orbits of planets, which means that the planet and
the asteroid circle the sun on the same elliptical path.
Earth and a few other planets have asteroids like this.
For some, a more interesting question is, how did these asteroids come into being?
Our solar system came into existence about 4.6 billion years ago when a large cloud of
gas and dust collapsed.
Following this event, most of that material fell to the center of the cloud and resulted
in the formation of the sun—the central star of our solar system.
Planets were formed from some of the condensing dust in that cloud, but not all celestial
material had the chance to be incorporated into planets.
The leftovers from that time took the form of asteroids.
Asteroids vary greatly in terms of their shape and size.
An asteroid can be as large as Ceres, nearly a thousand kilometers wide.
On the other end of the spectrum, the smallest asteroid ever studied is a space rock called
2015 TC25.
It’s 2 meters wide and was observed when it made a close flyby of Earth in October
2015.
Almost all asteroids are irregularly shaped, although a few big ones, like Ceres, are nearly
spherical.
Asteroids are also cratered or pitted, and their surface is thought to be covered in
dust.
Asteroids orbit the sun in elliptical orbits, but additionally, they also rotate, sometimes
tumbling haphazardly through space.
They may even have their own moons!
We know of more than 150 asteroids that have a small companion moon, and some have more
than one!
Asteroids are found in three main regions of our solar system.
A significant amount of asteroids are found in the Asteroid belt, which lies between Mars
and Jupiter.
Then there are Trojan asteroids—a large group of asteroids that share the orbit of
planets around the Sun.
Jupiter Trojans are the most well-known and numerous Trojans.
The total number of Jupiter trojans larger than 1 km in diameter is believed to be about
1 million!
Finally, there are Near Earth Asteroids, or NEAs.
These circle closer to Earth than the sun.
It is believed that nearly 10,000 of all known asteroids are NEAs.
Asteroids are known to be composed of clay and rocks, as well as metals like nickel and
iron.
Now, since some asteroids are very close to Earth, in comparison to other celestial bodies,
is it possible for them to slam into our planet?
Absolutely!
Ever since Earth came into being, it has been struck relentlessly by asteroids and comets.
In fact, the most popular theory regarding the extinction of dinosaurs is related to
an asteroid that slammed into Earth, causing widespread destruction, obliterating most
life forms in the global aftermath.
Although many celestial objects approach our planet, a significant number of them get burned
up in the atmosphere and never make it to Earth’s surface.
According to NASA, space rocks smaller than 25 meters will most likely burn up as they
enter Earth's atmosphere.
However, some larger asteroids do make it through the atmosphere and impact our planet’s
surface.
In 2013, an asteroid slammed into the atmosphere over the Russian city of Chelyabinsk.
The shock wave created by this event injured 1,200 people.
An asteroid capable of causing a global apocalypse would have to be more than 400 meters wide.
Impact from such an asteroid would cause massive destruction of both life and property on a
global scale.
Fortunately, asteroids that huge strike Earth an average of once every 1000 centuries.
All in all, asteroids can and do orbit near our planet, but most will never approach Earth,
and even if they do, they usually get burned up in the atmosphere before ever making contact
with our planetary surface.