For centuries humanity has looked up at the stars and wondered if we’re alone in the
universe.
We’ve dedicated much time and money trying to determine if anyone else is out there,
and recently there’s been a lot of excitement in the scientific community over a newly detected
object hurtling towards our solar system.
For some this was a chance to prove the possibility of alien life.
In the wee hours of the morning of August 30, 2019 engineer and amateur astronomer Gennady
Borisov was scanning the horizon in Nauchnij, Crimea.
Using a telescope with a 650 mm (2.13 feet) aperture of his own design, he spotted an
unknown object and posted an animation of it crossing the sky in an online Russian astronomy
forum.
As word spread, other astronomers around the world began scanning for the object and making
their own observations.
Then the Gemini North Observatory, atop of Mauna Kea in Hawai'i using the Gemini Multi-Object
Spectrograph instrument was able to capture colored, detailed images of the object on
September 9th and 10th.
The William Herschel Telescope in La Palma, Spain was also able to take some images of
the object.
Unfortunately for alien enthusiasts, the object was declared to be a comet.
It’s been given the name 2I/Borisov.
Disappointing if you were hoping for little green men in a flying saucer, but a pretty
exciting discovery for the scientific community, especially since 2I/Borisov is interstellar.
What exactly does that mean?
Well, first let’s start with what a comet is.
Many have referred to comets as ‘dirty or ‘cosmic’ snowballs.
They are balls of frozen gases, rock and dust that orbit the sun.
When a comet's orbit brings it close to the sun, the ice on its surface vaporizes.
It spews dust and gases to form a giant glowing head and frequently also produces a tail.
Comets vary in size, but typically the nucleus or center of a comet is around 6 miles (10
km) wide.
The width of the coma, or the cloud that forms around the nucleus, changes size depending
on how close the comet is to the sun.
Scientists have studied comets with comas that are 50,000 miles (80,000 km) wide.
A comet’s tail also varies in length due how much it's being heated by the sun’s
radiation.
Comet tails range from short to extremely long.
The longest comet tail recorded to date was the tail for Comet Hyahutake with a length
of 3.3 AU or 3.3 times the distance from the earth to the sun, some 307 million miles (494,068,608
million km).
Two main types of comets orbit in our solar system.
Ecliptic or short periodic comets are generally defined as those having orbital periods of
less than 200 years and follow the ecliptic plane, the same plane in which the planets
lie.
Ecliptic comets tend to be around 70 AU or roughly 70 x 93 million miles (70 x 150 million
km) or less from the sun.
These comets are thought to have been created in the Kuiper Belt, a circumstellar disc composed
of gas, dust, planetesimals and asteroids that orbit around the sun from beyond Neptune.
A well known ecliptic comet is Halley’s comet which passes earth's vicinity about
every 75 years.
You or your parents may remember Halley’s comet passing the Earth in 1986, a time when
Magnum, P.I was on American TV and shoulder pads were in style.
Wait, was that really 1986 or now?
Anyway, the second type of comet are nearly isotropic or long-period comets which originated
in the theoretical Oort Cloud, a spherical bubble of icy cosmic debris encasing our solar
system.
The Oort Cloud is considered theoretical because it’s at the farthest edge of our solar system
and we haven’t yet observed it.
It’s thought to begin some 2,000 to 200,000 AU or 0.03 to 3.2 light-years away from the
sun.
We hypothesize it exists because we’ve observed some of its effects on the solar system.
There are likely billions of comets orbiting our Sun, many from afar in the Oort Cloud,
but as of July 2018 we are only aware of 6,339 of them.
Back to newly discovered comet 2I/Borisov.
Why 2I/Borisov is considered so unique is because it’s interstellar meaning that it
originated outside our solar system.
It formed from cosmic material surrounding another star millions perhaps billions of
years ago and unimaginably far away.
Due to some unknown massive cosmic event, the comet is now traveling through our solar
system.
2I/Borisov has been determined be interstellar because of its orbit and how fast it’s moving.
The comet’s trajectory is extremely hyperbolic with a wide arc that approaches from one direction
and leaves in another, marking it as an object just passing through.
Amazingly, the comet is travelling at a breakneck velocity of 93,000 mph (150,000 kph), that’s
nearly 26 miles per second (nearly 42 km/s)!
Another clue that the comet is from outside our solar system is that it’s not gravitationally
bound to the sun.
2I/Borisov is only the second object we’ve ever detected as originating outside of our
solar system.
The first known interstellar object was Oumuamua which was first observed on October 19, 2017
by Canadian physicist and astronomer Robert Weryk using the Pan-STARRS telescope at Haleakala
Observatory in Hawai'i. Oumuamua means in Hawaiian “scout or messenger from our distant
past”.
Unfortunately, Oumuamua was 40 days passed its perihelion, or the point that is as close
to the sun as it was going to get.
Also it was already some 21,000,000 miles or 0.22 AU (33,000,000 km) from Earth and
headed out of our solar system when it was detected, so scientists didn’t have much
time to study it.
Awesomely, we discovered 21/Borisov during its arrival to our solar system, which gives
us much more time to observe it.
Through mid November 2019, the comet is observable with some telescopes in the Northern hemisphere.
It will cross the celestial equator on November 13th and enter into the southern sky giving
astronomers and enthusiasts in Australia and other southern regions the possibility of
viewing it.
On December 6th, the comet will be an equal distance of about 2 AU from the sun and earth.
Its perihelion is December 8, 2019.
While 2I/Borisov will peak in brightness in mid December, unless it fades or disintegrates
unexpectedly, the comet should be observable with moderate-sized telescopes until April
2020.
After that it will only be observable with larger professional telescopes through October
2020.
Since 21/Borisov began its journey so long ago to arrive in the vicinity of our solar
system now, we can only speculate about the system it came from.
From its entry into our solar system, the comet originated from the direction of the
galactic disk of the Milky Way.
Some scientists have proposed that 21/Borisov originated in Kruger 60, a binary star system
composed of a pair of red dwarf stars some 13.15 light-years away from earth.
Extrapolating from the comet’s orbital parameters determined so far, astronomers at the Adam
Mickiewicz University in Poznań, Poland in Poland have modelled and rewound 2I/Borisov’s
trajectory through space accounting for the gravitational influence of 648 star systems
it passed.
After a series of 10,000 simulations, where researchers varied the comet’s orbital parameters
and Kruger 60’s location and velocity, they’ve found that about 1 million years ago, 2I/Borisov
passed just 5.7 light-years from the center of Kruger 60, moving fairly slowly--just 2.13
miles per second (3.43 kilometers per second).
Yes, that’s still very, very fast, however, that’s a slow enough speed to indicate origination,
rather than the comet just passing by.
However, Kruger 60 results are preliminary and more simulations will be done as researchers
continue to gather more data while observing 2I/Borisov.
So far, 21/Borisov is displaying the characteristics of a regular comet.
A debate is currently raging among scientists as to how large the nucleus of the comet is.
The present estimate is between .8 of a mile to just over 4 miles (1.4- 6.6 km) wide with
a tail of around 6 miles.
This is in contrast to Oumuamua which seemed more like an asteroid rather than a comet
with its odd oblong shape and unusual orbital characteristics.
It lacked a coma and a tail.
However after scientists analyzed data from many different observatories, they realized
that Oumuamua underwent non-gravitational acceleration.
Something besides just the gravity from our solar system affected the trajectory of Oumuamua.
Probably the source of this acceleration was jets of gas coming off the object.
This behavior is similar to how when near the sun, ice in comets sublimates or turns
into a gas without going through a liquid stage.
The gas can push the object along and usually emits large amounts of dust.
However, we couldn’t see the outgassing for Oumuamua.
It’s speculated that the comet had used up all of its dust on its interstellar travels
or had dust particles are a size we had trouble detecting.
Using telescopes, scientists have measured the light being scattered off the gases in
21/Borisov’s nebulous coma.
Measuring the light spectrum of 21/Borisov allows us to analyze the chemical composition
of the ices in the comet that are undergoing sublimation.
Knowing which chemicals are contained within the vapor of this cosmic snowball gives us
a glimpse into the ancient building blocks which make up another planetary system.
So far, scientists have reported the detection of cyanide in 2I/Borisov which is commonly
found in regular comets born in our solar system.
Instead of analyzing the light coming off of 21/Borisov, wouldn’t it be easier to
retrieve a sample from the comet?
Scientists would love to collect material from the comet, but it’s moving too fast
for that.
Researchers have studied whether it would be possible to intercept 2I/Borisov.
While it is feasible, it’s pretty unlikely.
Assuming that we were ready to launch immediately as of September 2019, using the latest heavy
launch technology and calculating the perfect trajectory, at a speed of 21.1 miles a second
(34km/s) a very light payload could intercept 2I/Borisov in 2045.
Meanwhile, the European Space Agency (ESA) are currently building a robotic spacecraft
called the Comet Interceptor which is planned for launch in 2028.
The mission plan is to ‘park’ the spacecraft at a Sun-Earth Lagrangian point or a point
where the gravitational forces of large orbiting bodies and the centripetal force of orbital
motion match to maintain its position relative to the large orbiting bodies, in this case
the sun and earth.
The Comet Interceptor will be parked at L2 which is about 930,000 miles (1.5 million
km) behind Earth as viewed from the Sun..
Once parked, the Comet Interceptor will wait for up to three years for a long-period comet
to flyby at a reachable distance.
If all goes well the Comet Interceptor will deploy probes to inspect the passing comet,
collecting some of the coma and sampling for gas composition, dust flux, density, magnetic
fields, as well as plasma and solar wind interactions, to build up a 3D profile of the region around
the comet.
There’s a chance that the Comet Interceptor could end up inspecting an interstellar comet.
It was just about 2 years between Oumuamua and 21/Borisov visiting our solar system.
Scientists speculate that we receive interstellar objects visiting fairly regularly.
However up until now in history, we simply didn’t have the technology to discover them,
observe them or realize that they were interstellar travellers.
Not only would intercepting and studying an interstellar comet tell us a lot about another
planetary system, it could provide us with proof of alien life.
An interstellar comet could carry microbial or animal life capable of surviving the harsh
conditions of space, traces of the dead remnants of alien life via as chemical or biosignatures
or so-called techno-signatures or technological artifacts in the comet debris left by aliens.
So while 21/Borisov turned out not to be an alien spacecraft, studying the comet may provide
us with some clues that help us to determine if there is life aside from us in the universe.
Do you think 21/Borisov is an important discovery?
Why or not?
Let us know in the comments!
Also, be sure to check out our other video Astronomers Are Speechless After Spotting
THIS Inside Black Hole!
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