‘Aliens’ Is Not A Scientific Explanation For Interstellar Asteroid ʻOumuamua
“We often say that extraordinary claims require extraordinary evidence, and in all of these cases the evidence is very, very ordinary indeed. It’s worth keeping our mind open to the possibility that there’s more out there in the Universe than we presently realize, but not to embrace those possibilities as likely in any way whatsoever. When you leap to explanations that are fantastic, it’s all too easy to forget about the most likely explanations, which often involve nothing more than the natural phenomena already present and well-understood in the Universe we know.
In the case of interstellar interloper ʻOumuamua, we should be looking at the natural explanations first and foremost, not speculating about something for which the only evidence is our own wishful thinking. After all, what can be asserted without evidence can — and should — be dismissed without evidence.”
When you find a new phenomenon in the Universe, one that you’ve never seen before, the opportunity to discover something new about your reality is unparalleled. Oftentimes, you’ll try to use what you know to infer what behavior you expect, but it’s usually just a first-order, naive approximation. Until you collect enough data, find enough objects that fall into the new category, and study them with the required precision and detail, you’ll merely be speculating about what’s going on.
Last year, our Solar System got a visit from an interstellar interloper, marking the first time that’s ever happened. It’s been an interesting ride, full of interesting science and fascinating findings. Which is why it’s maddening that the one time it makes news is when a couple of scientists from Harvard take off their scientist hat and run headlong into sci-fi speculations.
For what I’m sure won’t be the last time, invoking aliens as an explanation for what you don’t understand isn’t science. Don’t fall for it. Get the facts instead!
This Is Why Comets Glow An Eerie Green Color
“But even though things aren’t looking particularly good for this comet, there’s always a chance it will surprise us. Furthermore, the features that you can expect for this comet — the ion tail, the dust tail, the coma, and the nucleus — are common to practically all comets that enter our inner Solar System. When a comet gets warm enough, it creates an extended, gas-rich cloud known as a coma around its nucleus. If the coma contains carbon-nitrogen and carbon-carbon bonds, the Sun’s ultraviolet light will excite the electrons inside it, causing them to emit a green glow when they drop down in energy. And whenever you see that green glow, know that there’s a chance of the comet’s nucleus splitting apart. It may not happen this time, or even most times, but there’s a chance for a visually spectacular show. When it comes to skywatching, it’s hard to ask for more.”
We typically think of comets as frozen mixes of ice and rock, but they’re so much more. There’s dust and volatile compounds present, and when the light and heat from the Sun interacts with the surface, it kicks up molecules into a gaseous, diffuse coma. This coma then gets struck by the ultraviolet light from the Sun. The dust particles get accelerated, creating the main comet tail you’re used to, but there are gas particles in the coma that simply get kicked to higher energies. If there’s enough cyanogen (CN) and diatomic carbon (C2) molecules present, they’ll create a green color due to their atomic transitions. And whenever you see that color, know that there’s the potential for the cometary nucleus to split, creating a spectacular outburst.
This may not happen for the “Incredible Hulk” comet lighting our skies today, but there’s always a chance. Don’t miss yours!
No, Comet Tails Don’t Make Meteor Showers
“When the debris from a comet or asteroid collides with the revolving Earth, the incredibly fast relative motion causes these tiny particles to burn up in the atmosphere, producing a brilliant streak of light.
Most popular explainers attribute these showers to cometary tails, but that’s simply not true.
Tails, created by the Sun’s effect on a comet or asteroid, are pushed away from the Sun, and this material spreads out rapidly, never to collide with Earth.”
You’ve heard the simplistic explanation before: that comets emit tails, those tails collide with Earth, and that’s where meteor showers come from. It’s an explanation that even NASA has given from time to time, and it’s a complete fabrication. Meteors that you see during a meteor shower have literally zero connection to cometary or asteroidal tails, and that’s easy to show: tails are always emitted away from the Sun, so the next time this tail material orbits the Sun and comes back near Earth, it’s much farther away and won’t collide with our world at all. But there is a debris stream due to the breakup of the central core of the comet or asteroid in question, and that gets spread out along the orbit over time. When Earth passes through that debris stream, that’s where meteor showers truly come from.
Don’t miss the full story, including a slew of spectacular pictures, on this edition of Mostly Mute Monday!
Sorry, Doomsday Forecasters, Earth’s Mass Extinctions Occur At Random
“Unfortunately, it’s human nature to seek patterns wherever things occur, but in this case, the evidence is far too weak to bet against randomness in any way. It’s important to remember that just because we don’t see evidence for periodic events doesn’t mean they don’t occur, but it’s important to not go chasing after a phenomenon that doesn’t have the evidence supporting its reality. Asteroid and comet strikes may have increased likelihoods at certain times, and there may be a periodic effect for CO2 levels and the carbon crustal cycle, but neither one has any evidence linking them to mass extinctions. When it comes to catastrophic events for the planet, and the species that inhabit it, randomness is as good as it gets.”
We’ve all wondered, at some point, if the asteroid that wiped out the dinosaurs isn’t a phenomenon that might not have been completely at random, but rather caused by a periodic, cosmic occurrence. Could our motion through the galaxy cause asteroidal or cometary impacts to occur more frequently at certain times? Would those times be periodic? And if so, could it make a mass extinction event more likely at certain times? This doesn’t need to be restricted to asteroids, but could be related to periodic geological or climatic changes as well. Fortunately, we know how to analyze this type of data, and to look for patterns in whether these extinction events appear at random or at uniform spacings. In 2013, the best analysis ever of this was undertaken by Fabo Feng and Coryn Bailer-Jones. As they conclude, in their own words: “…the time distribution of mass extinction events is consistent with being randomly distributed in time. There is no need to resort to anything more exotic.”
If you wanted to forecast our natural doomsday, the Universe isn’t going to help you out. Earth’s mass extinctions occur at random, and we’ve got the scientific evidence to back it up!
Interstellar Visitor ‘Oumuamua Was Shaped By Cosmic Particles
“We think of space as being an empty place, but the truth is that there are dust grains, particles, neutral atoms, ions, and cosmic rays zipping through the entirety of the galaxy, even when there are no stars. As an object moves through space, circling the galaxy at hundreds of kilometers per second (and moving relative to most other objects at tens of kilometers per second), it’s constantly bombarded by large numbers of small, fast-moving bits of matter. Just as water and sand will smooth out and erode pebbles and cobbles in the ocean here on our world, the cosmic equivalent — the interstellar medium — will have the same effect over extremely long timescales on ejected icy bodies.”
When scientists discovered ‘Oumuamua last year, they were surprised to find that it not only originated from outside our Solar System, but possessed bizarre properties we had never seen before. It was extremely elongated, tumbled irregularly, and had a never-before-seen composition: a carbon crust over an icy interior. Despite heating up to 550 °F (290
°C), it never developed a tail, a coma, or showed any ejecta. Many have proposed exotic or recent origins for this interstellar interloper, but in this case, simplicity rules: it may just be a cosmic pebble in the galactic sea. The interstellar medium is full of particles, and ‘Oumuamua, like most interstellar objects, should move at about 0.01% the speed of light through the galaxy. Over time, it should be worn down in exactly the fashion we see. As we discover more objects with an origin beyond our Solar System, we fully expect they’ll appear quite similar to this one.
How was ‘Oumuamua shaped? Likely by cosmic particles, rather than anything exotic. Come find out the science behind how.
How Can We Tell If A Space Rock Came From Outside Our Solar System?
“But when we examined its orbital properties, a real shock came. First off, it’s highly inclined to the plane of the Solar System, something that normally only occurs for object originating from the Oort cloud or the outer Kuiper belt. An asteroid like this is virtually unheard of. Second off, it was moving fast; far too fast to have been caused by conventional means. Even if you began with this object an infinite distance away and let the full gravitational effects of the Solar System pull it in, it wouldn’t be moving this quickly. The only way to get an object moving at these tremendous speeds is with a gravitational encounter with a very massive planet: a gas giant.
But that’s where the third surprise comes in. If you trace back its orbital path, there’s no way it could have occurred that way. None of the planets encountered it in the past; it’s completely gravitationally unbound.”
On October 19th, we detected an object that was unlike anything else we’d ever seen before. It was moving too fast at too unusual of an angle to be either a comet or an asteroid, and was too thoroughly gravitationally unbound to be hurled in by a planet, whether known or unknown. Based on what we detected, there’s only one conclusion that makes sense: this object came from outside our Solar System. These interstellar interlopers have long been theorized, but this is the first time one has ever been seen. Without a tail or coma at all, it’s unique among objects that come from so far away, and yet follow-ups have verified exactly what we hoped for. This is the first object to ever have an extra-solar origin, and is likely the first of many that we’ll find.
Here are the criteria for evaluating whether something came from beyond our Solar System, and how we’ll find out even more next time!
The Comet That Created The Perseids Might Bring An End To Humanity
“Every object in our Solar System that takes the plunge from out beyond Neptune to our inner reaches, where the rocky planets lie, will become a comet. As it nears the Sun, its ices melt, creating the tails we associate with them, and also creating a debris path that can create meteor showers if they cross Earth’s orbit. For thousands of years, the most consistent, spectacular meteor shower has been the Perseids, created by Comet 109P/Swift-Tuttle.
At its incredibly large size (26 kilometers across) and speed, it contains nearly 30 times the energy of the asteroid strike that wiped out the dinosaurs. Over the next few thousand years, it will come perilously close to Earth. If Jupiter — which it also passes by — gives it just the slightest gravitational kick, it could be flung into the Sun, ejected from the Solar System, or hurtled directly into our world. If this were to happen, and it’s a real possibility some 2400 years from now, it would mark the largest mass extinction our world has seen in hundreds of millions of years.”
Enjoying the Perseid meteor shower this year, as perhaps you do every August? As you look up, the great cosmic show might have a lot more to offer than mere streaks of light, due to cometary debris brightly burning up in the Earth’s atmosphere. This year, Jupiter has slightly disturbed the debris stream, resulting in an increase in the number of meteors-per-hour, as the stream passes quite centrally through Earth’s location. Someday, unless we continue to get lucky, Jupiter just might have that same effect on the comet that spawned the Perseids: comet Swift-Tuttle. Only, instead of an enhanced shower, we’d get struck by this comet. With a top speed of 60 km/s and a size of 26 km in diameter, this would result in an impact 28 times more energetic than the impactor that wiped out the dinosaurs.
Comet Swift-Tuttle is the single most dangerous object known to humanity. Come enjoy our continued existence and learn about our possible future demise, while you still can!
How To Catch The Perseids And Beat The Almost-Full Moon
“The faintest meteors will be washed out; the brightest meteors will appear dimmer; the total rate of the shower’s peak, instead of about 100 meteors-per-hour, will be approximately halved. If you were hoping to get up early (or stay up very, very late) for a great view, you’re going to be sorely disappointed. Luckily for you, not only is the debris stream that creates the Perseids wide, but the views are quite good for a day or two before and after the peak.”
The full or almost-full Moon might be one of the most familiar sights in the night sky to those of us here on Earth, but it’s also the largest natural source of light pollution we have to contend with. The peak of this year’s Perseid meteor shower meant, if all things were equal, the best time to see the highest rate of meteors would be the pre-sunrise sky of August 12. But with a large gibbous Moon dominating the skies during that time, it’s actually one of the worst ways you can try and view the Perseids this year. Instead, go out when the skies are darkest: before the Moon rises just after the peak. Because of how wide the cometary debris stream that gives rise to the Perseids is, viewing the sky in the evening before the Moon rises on the 12th or even the 13th is a far safer bet.
Come get your fix of the great night sky views of August, just a week before the solar eclipse comes to your daytime skies!
Are Mass Extinctions Periodic, And Are We Due For One?
“If we start looking at the craters we find on Earth and the geological composition of the sedimentary rock, however, the idea falls apart completely. Of all the impacts that occur on Earth, less than one quarter of them come from objects originating from the Oort cloud. Even worse, of the boundaries between geological timescales (Triassic/Jurassic, Jurassic/Cretaceous, or the Cretaceous/Paleogene boundary), and the geological records that correspond to extinction events, only the event from 65 million years ago shows the characteristic ash-and-dust layer that we associate with a major impact.”
65 million years ago, a catastrophic impact from outer space caused the last great mass extinction on Earth, destroying 30% of the species that lived on our world at the time. These mass extinction events happened many times in Earth’s past, and the Solar System also passes through denser stellar regions of space periodically, as determined by the orbit of the Sun and stars in the Milky Way. It’s a combination of facts that might make you wonder whether the extinction events are also periodic, and if so, whether periodic impacts are predictable. If so, then shouldn’t we be aware of whether we’re living in a time of increased risk, and prepare ourselves for that possibility accordingly? After all, the dinosaurs didn’t have a space program or the capability of deflecting a dangerous object like the one that wiped them out.
But before we go that route, we should take a good look at what the data shows. Are mass extinctions periodic? Are we due? Let’s find out!