Author: Eric Malikyte

The Oort Cloud

The Oort cloud is thought to be a shell of icy material that surrounds our Solar System.

No. It’s not a literal shell but based on this illustration [insert image of Oort cloud] you can see that the orbits of these objects are thought to form something of a sphere.

This is where most astronomers think comets, even famous ones like Halley’s comet (which last visited us in 1986 and will make a return trip in 2061) come from.

Most of these objects, much like the objects in the asteroid belt, are relatively small. Ranging from a few meters to several kilometers wide.

But astronomers combing through data from the Dark Energy Survey have stumbled upon something incredible.

The largest comet ever discovered in modern times!

The Largest Comet Ever

Comet Bernardinelli-Bernstein, or 2014 UN271 officially (you decide which is easier to say), was discovered thanks to data captured by the Dark Energy Camera in Chile. Appearing in about 30 images of the approximate 80,000 that were originally taken during the DES’ 6 year survey of the night sky.

This image from the Dark Energy Survey (DES) is composed of some of the discovery exposures showing Comet Bernardinelli-Bernstein collected by the 570-megapixel Dark Energy Camera (DECam) mounted on the Víctor M. Blanco 4-meter Telescope at Cerro Tololo Inter-American Observatory (CTIO) in Chile. The analysis of data from the DES is supported by the Department of Energy (DOE) and the National Science Foundation (NSF), and the DECam science archive is curated by the Community Science and Data Center (CSDC) at NSF’s NOIRLab. CTIO and CSDC are Programs of NOIRLab.

The object is thought to come from the Oort cloud, in a region that is estimated to be 10,000 to 20,000 times farther from the Sun than the Earth is.

Its orbit is estimated to take around 3 million to 5.5 million years just to complete one loop around the sun.

The shocking thing is its estimated size, a whopping 60 to 160 kilometers across (37.28 to 99.4 miles), but despite the misleading language offered by some other youtube channels that report space news, while this object can be considered a minor planet…so too is pretty much every object in the asteroid belt, Kuiper belt, Oort cloud, and even Pluto and other objects like it. It’s a term that can basically refer to asteroids, comets, trojans, dwarf planets, and the list is quite massive.

Make no mistake, though, this object is HUGE!

A video I watched on the subject (not naming names here) misreported the object’s size as 23 miles across, but even at that estimate, if it were on a collision course with the Earth, we’d be screwed, even if it landed in the ocean.

But that video in question got some things very wrong about how objects behave when they hit the ocean. So, let’s dispel some misconceptions.

Ocean Impactors and Tsunamis

A 2016 study by Galen Gisler aimed to uncover how asteroids and comets really behaved when hitting the ocean. The typical Hollywood portrayal in movies like Deep Impact and Armageddon displays asteroids smashing into the ocean and creating massive Tsunamis that drown islands and create a watery graveyard for monuments like the Statue of Liberty.

Gilser’s team unveiled its findings at the American Geophysical Union’s Fall Meeting in San Francisco, showing off a 3D simulation of an ocean-impacting asteroid. Before this point, such a simulation had never been done, at least not in as much detail.

2016 Ocean Impactor simulation.

What the simulations uncovered, was that the tsunamis generated in Hollywood disaster movies were totally fictional.

Gilser had this to say about the simulation, “An asteroid impact is a point source and it only affects the immediate region around the impact point and moreover, to create a tsunami, you need something that disturbs the entire water column.”

Basically, this would be like throwing a rock into a pond. Yes, larger asteroids would produce waves, but they would disperse very quickly.

Tsunamis are produced under specific circumstances, usually during large-scale shifts of the seabed like submarine earthquakes or landslides. These events cause a large portion of water to be affected by their movement, affecting not only the water on the seafloor but penetrating all the way to the surface. That’s what creates giant waves.

Because tsunamis aren’t dispersive, they don’t lose energy as they traverse the ocean basin, allowing them to reach coastline cities.

Though, a large asteroid impacting the ocean would still be a dramatic display and would create “splashes” up to tens of kilometers tall. However, unless this impact is close to shore, it wouldn’t be very dangerous.

There is a caveat, though. A large portion of a hypothetical asteroid’s kinetic energy would be used up in vaporizing massive amounts of water upon impact. The water vapor produced is a potent greenhouse gas, so if a large quantity of it ended up in the stratosphere, it could linger there for years, altering the global climate.

But what would happen if comet Bernardinelli-Bernstein hit the ocean?

Let’s find out!

A Massive Impactor

Comet Bernardinelli-Bernstein is absolutely huge. Even at the lowest estimate, 40 kilometers wide, it’s my speculation that it would be absolutely devastating to the Earth.

The maximum depth of the Earth’s ocean is around 11.02 kilometers (6.84 Miles). But this object in particular is much, much larger than that.

For this purpose, I’ve run two different simulations, taking some liberties with a few details to fill in what we don’t know about this comet.

Universe Sandbox automatically increases mass based off of an object’s size. So I took one of its preset comets and bumped it up to a radius of 160 kilometers, then I smashed it into the Earth…three times. As you can see, the first impact happens over a series of islands, and it’s absolutely devastating, creating a massive cloud of debris in space.

The other two simulations I ran in Universe Sandbox were more focused on the Ocean, though I found it really hard to control where Comet BB impacted.

But the interesting thing about one of these was that even though the thing impacted in the ocean, and it appeared the US was fine, when I viewed the country on the night side, half of the lights in half of the country and Canada were just GONE.

While the second two simulations appear to show that the Earth gets off relatively unscathed, one look at the Earth’s temperature tracker shows that over the course of the simulation the Earth’s average temperature went up to 24 to 26 degrees Celsius from a pre-impact average of 7 or 8 degrees Celsius.

Now, this isn’t hot enough to make the planet completely uninhabitable—that limit is around an average of 35 degrees Celsius—but after I sped the simulation up, it ended up causing the average temperature to absolutely plummet.

An impact like this would probably push the planet into an ice age.

Things don’t look much better with the other two calculation-based simulations I ran through impact.ese.ic.ac.uk, which I’ve linked to so you can run your own simulations.

Comets are typically less dense than asteroids, but even so, despite hitting the ocean, it still created a crater on the ocean floor 3,660 kilometers in diameter. For some perspective, the Chicxulub crater (which is the crater left over from the asteroid that killed the dinosaurs) is only about 180 kilometers in diameter.

Based on the average velocity and impactor angle of most comets, the simulation predicts that the Earth’s orbit and tilt wouldn’t change much, but the length of a day could change.

But keep in mind, this is a very old impact simulator, so, some values could be off.

But Universe Sandbox’s simulation isn’t exactly what would happen should an object of this size hit the Earth either, but it’s a nice visualization, and at lower speeds is more accurate than you might think. Suffice it to say, the effects would be devastating, as the object is clearly large enough to penetrate the ocean floor.

This is just my guess [speculation alert] (we get it, computer), but I think the impact would be enough to send record breaking Earthquakes rippling through the crust of the planet. Not only that, but if the impact happened in the Atlantic ocean, which at one point stretches 5,980 kilometers, most of the ocean floor would be a crater. That certainly puts things into perspective.

Suffice it to say, I don’t think we’d live to tell the tale.

Impacts like this don’t happen very often, we’re talking about a timescale longer than the Earth’s age, so around 4 billion to 4.5 billion years. That means, that an impact of this scale hasn’t happened to the Earth since the time of the moon’s formation when Theia crashed into proto-Earth (a subject we covered in another video, linked in the description.)

But you can rest easy, because the closest approach of Comet Bernardinelli-Bernstein, known as perihelion, is going to be a little beyond the orbit of Saturn, or about 10 AU.

That is so far away from the Earth that you will need a telescope to see it.

So, I don’t think we’ll have to worry too much about this thing, even at its closest approach. Adding to this, it will also be outside the normal plane of the Solar System.

However, seeing some of the comments on other videos about objects like this potentially disturbing hazardous bodies in the asteroid belt got me thinking about the misconceptions surrounding distances in the solar system.

So let’s put to bed some of these fears.

Distances in the Asteroid Belt

Let’s suggest for a moment that an object like Comet Bernardinelli-Bernstein were to come closer, say the orbit of Mars, and that it was going to cross the asteroid belt in the process. What is the likelihood that it could disturb the orbits of objects in it, and could it send an Earth ending asteroid hurtling toward our planet?

Well, the average distance between objects in the asteroid belt is actually around 1 million kilometers (or 600,000 miles).

Asteroid Belt

Science fiction movies, anime, and video games tend to depict asteroids bunched together, but this is totally inaccurate to how they actually behave in our solar system.

For a comet to disturb the orbit of objects in the asteroid belt, it would have to come close enough to interact gravitationally with one of those objects. Though there are millions of objects in this region, the chances of this happening are probably pretty slim.

In fact, I couldn’t find any information pertaining to this question, so it isn’t even a concern to most of the scientific community it seems.

We’re more likely to be hit by near-earth objects, or Atira asteroids, than the ones all the way out in the asteroid belt.

In any case, this unusually large comet is a fantastic find.

Its closest approach will be in 2031, and scientists are clamoring to put together plans to observe and maybe even land on it to collect samples.

We don’t know much about the Oort cloud, or the composition of the objects out there, so being able to do this would be a massive scientific achievement. I can’t wait to see what happens with this object, and you can bet I’ll be watching for news surrounding it.

Source:

https://www.space.com/newfound-comet-biggest-recorded-history

https://www.sciencefocus.com/planet-earth/how-hot-could-earth-get-before-its-uninhabitable-for-humans/

https://pweb.cfa.harvard.edu/research/topic/minor-planets-and-comets

https://www.space.com/35081-asteroid-impact-ocean-computer-simulations-solar-system.html

https://www.lpi.usra.edu/science/kring/Chicxulub/discovery/#:~:text=The%20crater%20appears%20to%20have,confirmed%20impact%20structures%20on%20Earth.

https://science.howstuffworks.com/asteroid-belt.htm

https://nymag.com/intelligencer/2017/07/climate-change-earth-too-hot-for-humans.html

Image Sources:

Oort cloud.png by Pablo Carlos Budassi – Own work, CC BY-SA 4.0, https://creativecommons.org/licenses/by-sa/4.0

Comet Halley close up-cropped.jpg by ESA, CC BY-SA 3.0 igo, https://creativecommons.org/licenses/by-sa/3.0/igo/deed.en

DECam iphone insert.PNG by DES Collaboration – DES Collaboration, CC BY-SA 4.0

2014 UN271.jpg by Tony873004 – Own work, CC BY-SA 4.0 International, https://creativecommons.org/licenses/by-sa/4.0/deed.en

Comet Bernardinelli-Bernstein annotated – noirlab2119b.jpg by Dark Energy Survey/DOE/FNAL/DECam/CTIO/NOIRLab/NSF/AURA/P. Bernardinelli & G. Bernstein (UPenn)/DESI Legacy Imaging Surveys – https://noirlab.edu/public/images/noirlab2119b/, CC BY 4.0, https://creativecommons.org/licenses/by/4.0

Illustration of Comet Bernardinelli-Bernstein.jpg by NOIRLab/NSF/AURA/J. da Silva (Spaceengine) – https://noirlab.edu/public/images/noirlab2119a/, CC BY 4.0

Visualization of an asteroid splashing down in one of Earth’s oceans. (Image credit: LLNL)

Subduction-en.svg by KDS4444 – Own work, CC BY-SA 4.0

Tsunami comic book style.png by Anthony Liekens – Own work, CC BY-SA 3.0, http://creativecommons.org/licenses/by-sa/3.0/

Moon – Giant Impact Hypothesis – Simple model.png by Citronade – own work, CC BY-SA 4.0 International