Space is full of diverse objects we don’t know much about. That’s why
they capture our interest every time we spot them.
But with this thrill often comes fear, especially whenever there’s a comet heading toward us.
It's no surprise, we haven't got a clue on how to stop an asteroid or comet from hitting the planet.
But soon, having such technology might become vital. Now scientists operating
one of the most advanced astro-cameras have just made an eye-opening finding.
They detected a monster comet that is already in our solar system, and it's moving fast.
In August of 2013, scientists launched a project to map a portion of the Southern
Sky which completed in 2019. It's called the Dark Energy Survey. An
incredible 570-megapixel camera called the Dark Energy Camera (show this camera
https://news.fnal.gov/wp-content/uploads/2019/01/dark-energy-camera-12-0331-04D.hr_.jpg) grabbed data
from over 300-million galaxies amounting to 50 million megabytes. Scientists have
just begun to go over that data...and they found something that they didn't expect.
Data created 32 images showing a blurry dot in the darkness of space,
located about 2.5 billion miles (4 billion kilometers) away from Earth.
It wasn't until it got close to the planet Uranus (about 3-billion km - 1.8 billion miles) that
astronomers were finally able to figure out what the strange object was.
What scientists detected was a comet with a size a thousand times above average.
It was dubbed C/2014 UN271, also known as Bernardinelli-Bernstein after its discoverers.
Given the amount of sunlight it reflects, astronomers speculate the object's diameter is
somewhere in between 60 to 125 miles (100 to 200 km). That’s an insanely big number. To compare,
an asteroid that wiped Dinosaurs out of existence is thought to have been just around
6-9 miles wide (10-15 km). But since Bernardinelli-Bernstein
is still so far away, it's not clear whether the calculations are close to real measurements.
Another fascinating fact about this comet is that the last time it entered our solar system was
3 million years ago. That is about the same time a well-known human ancestor "Lucy" lived.
Given such a long orbital period, it seems the comet should’ve come from a very distant place.
And it happens there’s just such a place believed to be home to trillions of comets.
It’s a place called the Oort Cloud, a spherically shaped region of space containing various remnants
from the early ages of our solar system. The Oort Cloud is located far beyond the dwarf planet
Pluto, and might stretch to 100,000 AU from our star. So scientists think Bernardinelli-Bernstein
is the most remote comet we've successfully spotted on its way to us. Such an early
discovery gives us plenty of time to study this comet and eventually explain its nature.
So when will it get close to us?
According to scientific estimates, the closest encounter with the Bernardinelli-Bernstein comet
will come in 2031. So far, astronomers claim the comet imposes no threat as it will fly by
at a significant distance from us. The closest it will get is 11 astronomical units. That's
about ten times farther away from the Sun than the Earth. It won’t even be visible in the sky
with the naked eye. But since comets' behavior is hardly predictable, we don’t know what to expect.
Unlike Bernardinelli-Bernstein, certain celestial objects will get much closer to us,
and a lot sooner. One of such space guests is a
killer asteroid that will fly by within less than 0.07 AU!
In just about a year, a binary asteroid named Didymos, accompanied by the smaller Didymoon, will
make a near-Earth approach. The bigger asteroid is roughly 780 meters (roughly 2500 feet) in
diameter, while the smaller one is just about 160 meters (approximately 500 feet). However,
that’s more than enough to make a crater that is six miles wide and demolish entire cities.
Even space rocks that are 500 feet (150 meters) wide are capable of exploding with the energy
equal to a nuclear bomb. A meteor, a tiny piece of an asteroid or a comet, that exploded
over Chelyabinsk, Russia, created a massive shock wave. As a result, tons of buildings were damaged,
and roughly 1,500 people were injured. And it was only about 65 feet wide (about 20 meters).
But data concerning asteroid impacts has become even more disturbing.
NASA has recently conducted an experiment that proved we wouldn’t be able to do
anything about an asteroid heading straight toward us, even if we had a 6-month warning.
The simulation of the hypothetical scenario involved an asteroid at a distance of 35 million
miles (more than 56 million km). Throughout each phase of the exercise that lasted a week,
scientists received more and more data about the asteroid. They found out about the object’s
course, odds of it hitting our planet, and its size. But they couldn’t come up with a
working solution to deflect it. Turns out, we haven’t yet invented a spacecraft that could
eliminate such a threat within 6 months. In fact, such a mission would take us 5-10 years!
In the simulation, the asteroid would’ve landed on Eastern Europe. In fact, the only
way to escape the big rock was to evacuate the impact area… and that's not helping us too much.
But as we know, some things that don’t work out in theory can show good results in practice.
So now NASA plans to smash a spacecraft about the size of a refrigerator into the smaller Didymoon
asteroid that we mentioned earlier. The mission is called Double Asteroid Redirection Test or (DART).
The idea is to take the half-ton spacecraft and crash it into Didymoon at around 4 miles
per second (6.6 km/s). The launch will take place sometime between November 24, 2021,
and February 15, 2022. However, the collision should happen between September and October 2022.
This is going to be the very first test using the kinetic impactor technique to alter an
asteroid's trajectory and speed, and will be a kind of military training in terms of space.
Now, Didymos doesn’t threaten Earth yet. But NASA’s database contains more
than two thousand potentially hazardous asteroids that can get as close to us
as 0.05 astronomical units (around 7.5 million km or 4.6 million miles).
Asteroids and comets are often hard to detect, even with the most advanced technology. But at
times, people equipped with homemade telescopes make huge discoveries.
Just two years ago, an amateur astronomer named Gennady Borisov stumbled across a celestial
object with a peculiar trajectory. Turns out, he found a comet and not an ordinary one either.
It was later discovered by scientists that 2I/Borisov
is a rogue comet. This is because this type of a comet has no steady orbit,
and will freely float through space until affected by another celestial object.
As astronomers continued to study 21/Borisov, they used NASA’s Hubble Space Telescope
and Atacama Large Millimeter Array (ALMA) to figure out the comet’s
extraordinary composition. It had an abundance of carbon monoxide they didn’t expect to see.
And knowing about this high concentration of CO, scientists can make assumptions about its origin.
So far, astronomers have come to the conclusion it should have been created in a place overflowing
with CO ice. Such an abundance of CO ice is only present in space regions with a temperature below
-420° Fahrenheit (-250° Celsius). There are two theories about how the comet formed. It could’ve
been born around a red dwarf - a relatively small star with a low surface temperature.
Otherwise, it could be a tiny fragment of a dwarf planet.
This has become the first comet that entered our solar system from a place outside of our
star’s influence. But this is not the only thing that captured astronomers’ attention.
When approaching a star, a comet's particles start to melt and generate a fuzzy cloud around
its nucleus. This cloud is called a coma. So what scientists noticed was a unique polarization in
Borisov’s dust grains. Now, polarization is the direction light waves ripple in space.
The higher the polarization, the more focused the light is
in a single direction. That’s exactly what 21/Borisov’s coma demonstrated.
In the scientific community, this was a big deal.
Similar to the way our skin reacts to direct sunlight, the more a comet interacts with a star,
the bigger the impact on its materials. Eventually, the polarization of the comet’s
coma gets reduced. But what we see with Borisov’s comet is quite the opposite.
This can only mean one thing - it has rarely or never bathed in a star’s light, radiation,
or winds. So it is one of the most untouched and well-preserved comets we’ve ever detected.
This leads us to the conclusion that the comet contains unaltered
information about the materials that formed it in the first place,
which could’ve happened some thousands, millions, or even billions of years ago.
And since astronomers believe the birthplace of 21/Borisov partially resembles our solar system,
the comet can reveal valuable information about another solar system much like ours.
Borisov’s comet already traveled past our Sun in 2019. But this doesn’t mean there are no
other celestial objects only about to visit us. We can only hope our telescopes will look
in the right direction, and at the right time so that we can prepare ourselves once they show up.
It seems no matter how fast we technologically evolve, this is not quite enough to ensure
absolute safety and tranquility. Still, the most powerful resource we’ve got is our brains.
So it’s crucial that more and more people get involved in space science.
To stay up to date about other amazing things happening in our universe,
make sure to stay tuned here. Thanks for watching.