We say it all the time here on Astronomy Cast: the Universe is trying to kill us. This week, Pamela is joined by Dr. Phil Plait to discuss his new book, Death from the Skies. Phil and Pamela talk about asteroid strikes, solar flares and gamma ray bursts.
Death by Asteroid
Death from the Sun
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Dr. Pamela Gay: With me this week is ‘The Bad Astronomer’ Dr. Phil Plait. How are you doing Phil?
Dr. Phil Plait: I’m doing just fine.
Pamela: How does it feel to be an author nowadays?
Dr. Plait: Well, I’ve been an author before but when you do it once it could be a fluke. If you do it a second time then that’s showing that you might have a little bit more credibility. So I’m pretty happy to have another book out. It seems to be doing fairly well so I’m excited.
Pamela: Well and we’re excited to have you here today. As we’ve talked about a lot on this show, the Universe is trying to kill you, me, and everyone in the world. Death can come in many forms but thus far the planet Earth has managed mostly to make it out okay. So far at least we have – as long as you don’t happen to be a dinosaur.
Today you and I are going to talk about a few of the most likely and most interesting ways we may not be able to avoid death in the future. I guess the best place to start is what’s the most likely way that we could all die?
Dr. Plait: [Laughter] Actually calculating statistics on Astronomical events is a little tricky. The Sun IS going to turn into a Red Giant and it IS going to fry the Earth but not for another 6 billion years. So, the odds of you and me dying in this are zero. That’s the most likely kind of thing that’s going to happen – something inevitable as far as us listening to the Podcast or just living our lives today, far and away the most likely event is an Asteroid or a Comet impact simply because there are so many of them out there and it doesn’t take a really big rock coming in to cause a lot of damage.
So, the smaller the rock the more of them there are. There might not be that many dinosaur killers out there, the rocks that are 10 kilometers across (6 miles) but there are lots of little ones you know, a hundred yards across. Those can’t wipe out all life on Earth but if they come over a city, that would be bad.
Pamela: Now, we’ve all seen in movies and we can name these movies (although we shouldn’t because that would give them attention they don’t deserve)…
Dr. Plait: [Cough, cough – Armageddon]
Pamela: [Laughter] We’ve all seen these movies where they try and get rid of the problem by blowing up the rock. This is a really bad idea.
Dr. Plait: Well, yeah it’s bad for a lot of reasons. One of which is like imagine this thing is the size of Mt. Everest, 6 miles across something like that and it’s made of iron. A lot of Asteroids are made of iron. You can drop bombs on something like that all day long and it’s just going to laugh all the way down.
All you’re going to have happen is now you’ve turned an Asteroid impact into a radioactive Asteroid impact. That’s not very good. [Laughter] If we see an Asteroid coming in we may not know what it’s composed of. It might be iron; it might be rock; it might be what they call a rubble pile. Some of these Asteroids are basically shattered in place by low speed impacts. It’s like a bag of rocks or gravel. You can lob bombs at that and it just absorbs the impact and nothing happens.
So this argues that we should really be studying these things so we understand them better. We should be funding this better. We just don’t know enough about these kinds of Asteroids. So really just trying to blow it up isn’t a good idea especially if like at the end of the movie ‘Deep Impact’ which I watched actually last night as we were recording this they blew up a Comet 6 miles across when it was minutes away from impact. All you’re doing is taking one giant impact and turning it into a gazillion somewhat smaller impacts spread out all over the Planet. So you’re not really helping any.
The thing you REALLY want to do with these is to make them not hit [Laughter] the whole problem is they’re hitting us. If you make them not hit then you’re okay. You want to push them out of the way. You can think of a lot of ways of doing this. You can land a rocket on one and stick the back end of it straight up and use that to push it.
The problem with that is these rocks are spinning or tumbling and so you can’t really control which way your rocket is blasting and you want to be able to control this. You can in fact blow a bomb up on the surface of an Asteroid and then you’ll vaporize part of it and that vapor will expand and act like a rocket and push the Asteroid in the other direction.
Pamela: But again if it’s tumbling you’re still going to have problems.
Dr. Plait: That’s right and you can’t really control how much you’re pushing it. You might push it into an orbit that is only marginally dangerous into an orbit that’s VERY dangerous.
There’s a group of people called the B612 Foundation. They’re named after the little Prince who came from an Asteroid called B612. They want to put a Space Probe, a rocket off the side of an Asteroid not physically touching it but near it. This probe might have a mass of a couple of tons something like that so its own mass gives it Gravity. That Gravity can pull on the Asteroid.
So the Probe very gently fires its rockets and can tug the Asteroid out of the way using nothing but its own Gravity. It’s called a Virtual Tether or a Gravity Tug. This is a cool idea – it sounds ridiculous – but in fact these guys at B612 were talking – Astronauts, Astronomers, Engineers, smart folks – and they’re really out there trying to get this done, trying to figure out how to do it. It’s a brilliant idea and honestly I think it will work.
Pamela: And the nice thing about this is Gravity doesn’t care if the Asteroid is tumbling. Gravity doesn’t care in fact about anything other than where the heck is the center of Mass of the Asteroid.
So you launch something roughly the size of a fully-loaded semi-truck which you might have to do in 2 or 3 different trips to get all the pieces into orbit and we can practice ahead of time. We don’t have to wait for something to be on its way to destroy the Planet.
You take something out to the Asteroid Belt and just rearrange the Asteroid Belt a little bit to test out how well this process works. It’s completely straightforward. The math is completely straightforward. The hard part is figuring out how well we can maneuver in that sort of a situation.
Dr. Plait: Yeah, so the other thing it cares about too is the mass of the Asteroid. So if you have a REALLY big Asteroid you need a lot more time to be able to move it where you want as opposed to something smaller which you might just be able to move a lot more quickly.
The thing is these guys are threading the needle. These Asteroids are coming in and the Earth is 8,000 miles across so the earlier you can push this thing out of the way, the wider it’s going to miss the Earth by when it passes. What you really want is a lot of lead time so you don’t have to push it so hard and the lower mass Asteroid the better because then you don’t have to push as hard to get it out of the way in the first place.
The problem is we cannot control those things. Whatever is going to hit us is going to hit us. We have to keep our eyes open, check for these things and get as much lead time as we can.
Pamela: Well one of the problems about Asteroids in general is the Earth-crossing ones are often on highly elliptical orbits and that has some rather severe consequences. It means the one that’s likely to hit us is likely to come out of the Sun or at least the Sun’s direction. Those are kind of hard to see.
Dr. Plait: Right, a lot of the times you’ll read the newspapers and it’ll say we were just missed by an Asteroid last night. That’s really irritating. If you draw yourself a picture, if an Asteroid is coming past the Earth the only time we can really see it well is when it’s already on its way by.
When it’s coming towards us it might be coming from the direction of the Sun or it’s coming from a direction where the geometry makes it look like the Crescent Moon does – it’s not lit very well. So, it’s dark and just coming from a funny direction.
A lot of the times we really don’t discover these things until after they’re passed us. Look that’s a bit of a worry. We need to be searching for these things with even more eyes on the Sky than we have now to make sure we don’t miss them.
Pamela: So coming on-line in December is this wonderful system called Pan-STARRS that is going to be basically observing all of the Sky that it can every night, night after night after night and automatically subtracting one night’s images from the previous night’s to see if there is anything new or if anything moved. This system is going to be able to find Super Nova; it will be able to find Asteroids. It will be able to identify Variable Stars that we never knew about. It’s going to basically look at our inconstant Sky and nail everything that’s not constant very rapidly.
Hopefully this is going to be a way that we can find things that reflect light effectively. Once it is going, a few years later there is another system called the Large Synoptic Survey Telescope that is even bigger and will be able to find even smaller rocks.
Between these two systems, we should be able to get to the point that we’ve found close to all of the Earth-killing Asteroids and hopefully order of (I think they’re tasked with something like 90 percent of the Continent-destroying size rocks) it’s not everything.
Dr. Plait: A friend of mine, Dan Durda, I’ve actually known him for many years, is an Asteroid Specialist. He’s actually president of the B612 Foundation. He and I were talking the other day and he said the goal is to find 90 percent of all Asteroids that can cross Earth’s orbit that are bigger than 140 meters by the year 2025.
One hundred forty meters is sort of a combination of the smallest ones that can do a lot of damage that are also findable basically. If they’re much smaller than that they don’t do much damage and they’re harder to find. You take all of these factors into account and 140 meters seems to be about the right size to be looking for. Finding 90 percent of them in the next 17 years or so is a pretty good goal.
Pamela: That’s where we’re headed and we’re getting better at finding these things all of the time with new technologies, new ways to automate the search. It’s a fun way to go out and basically protect the planet Earth.
We’re working on finding ways to tug these things out of place when they are on bad trajectories. The nice thing is we’ve found a lot of them already. We’ve found significant double digit percentages we think of them already using statistics. As far as we know there is absolutely nothing headed our way.
Dr. Plait: Not at the moment. There’s nothing with a reasonable chance of hitting in the next few decades. There are some like the one called Apophis which is about 300 yards across, 300 meters across that’s going to pass by the Earth in 2029. We don’t know exactly how far away from the Earth this thing is going to pass. It’s actually very hard to know that this far in advance. As it gets closer we’ll know better but right now we don’t know.
The point is if it passes a little too close to the Earth, the Earth’s gravity will swing it really widely around into a different orbit. If it doesn’t pass close enough to Earth, the Earth’s gravity will only bend its orbit a little bit. If it passes at just the right distance, what Astronomers call the Keyhole; it will come back in seven years and smack us in 2036.
We really don’t want that to happen because something 300 yards across is BIG. That’s bigger than a city-killer by far. You don’t need anything anywhere near that big to wipe out a city. We don’t want something that big hitting us anywhere.
They’re taking this Asteroid seriously even though the odds of it hitting us are like one in 45,000 or something like that, very small. But they want to put a radio beacon on it actually so we can track its orbit perfectly. If it looks like it’s going to come back and hit us, use a Gravity Tug, put one of these things together and move it out of the way.
One of the things I really like about this is besides being able to keep us from getting all killed – which is something [Laughter] I’m all for that –
Pamela: But it would sell your book so well [Laughter]
Dr. Plait: That’s true as a promo I couldn’t ask for anything more. But one of the things that’s good about this is if you can move an Asteroid out of the way, you can move it into an orbit that might help you.
If we see one that’s a couple hundred yards across and made totally of metal (these things are iron, nickel and things that are actually difficult to mine on the Earth) we can actually move it into an orbit which is beneficial.
You move it into an Earth orbit and take your time and 20 years later you go back to it and start mining it when you have the technology to do that. It would probably pay itself off in just a few years.
Pamela: So it could kill us or it could help us build the next generation of autos.
Dr. Plait: Right. There’s a third choice too. There’s a lot of international wrangling over this because what if we see an Asteroid that’s coming in. We know its orbit well enough and it’s going to hit in say Kansas. We use our Gravity Tug and the Gravity Tug gets it pulled out of the way and then fails.
Then we recalculate the orbit and we find out it’s going to hit in Munich. Oops! [Laughter] so, what do we do? There are literally international lawyers who are hashing this out right now to figure out what to do in these cases and how to figure this stuff out. It’s a very complex situation.
Pamela: Wow and it’s a situation we’re going to have to deal with in our lifetime.
Dr. Plait: Yeah.
Pamela: Well, that was a cheery thought [Laughter] and unfortunately there’s actually some rather even shorter term ways that not necessarily Planet death will occur but Planet inconvenience could occur from the Skies. Those problems tend to come from our Sun rather than some Asteroids.
Our Sun is currently at a particularly long period of minimum. We’ve all been eagerly awaiting a new round of Sunspots with baited breath. This new round of Sunspots just could bring some fairly interesting things Earthward. Can you tell us a little bit about what we might expect from our Sun?
Dr. Plait: The Sun is magnetic. It has a magnetic field a little bit like the Earth’s in that you have a magnetic field generated somewhere on the interior and it pierces through the surface. If you were standing on the Sun and you had a compass you could use that to navigate although not very well because unlike the Earth’s magnetic field which basically pops out at the North and South Pole, the Sun has a very complex twisted magnetic field. Like almost like a huge ball of rubber bands. It’s just a complete mess. It’s a very complicated situation.
The Sun’s magnetic field changes in strength. It goes from a minimum like it is now where the magnetic field is very weak and then over time – over the next 5 and a half years – it builds up to a maximum and it’s very tangled. There are loops of magnetic field energy popping out all over the surface. Then 5 and a half years later it dies down and goes to a minimum again. Right now, like you said, we’re at one of those minima.
What this means is that there are very few Sunspots where the magnetic field pierces the Sun’s surface. It actually lets that part of the Sun cool a little bit and it doesn’t glow as brightly and so we see that as a dark spot. The Sunspots are sort of an indicator of what the Sun’s magnetic field is doing. If you went out with a telescope and pointed at the Sun, projected the image of the Sun on a piece of paper (because you DON’T want to be looking at the Sun through a telescope folks) [Laughter] you won’t see that many Sunspots. There have been very few in the past few months.
We are just now starting to see Sunspots from the new cycle. Nobody really knows what this means. It’s been awhile. It’s been an unusually long minimum and nobody knows what that means. Does that mean it’s going to be a weak maximum? Does that mean it’s going to be a really strong maximum? Nobody knows.
In 2003 we had just a rip-roaring maximum from the Sun. The magnetic field was a total mess and there were Sunspots all over the place. The way you want to think about this is to imagine having a net full of bedsprings. You pull these bedsprings until they’re all full of tension and then wrap them all around each other. They are then full of all this Potential Energy just waiting to snap. Then you poke it and when you poke it and one of them snaps and then it hits another one and that one snaps. They all start snapping all over the place. That releases a lot of energy.
Well, the same thing happens with the Sun. The magnetic field was all tangled up – it’s a bunch of springs – and if something happens on the Sun, one of them snaps or there’s some sort of disturbance, it can let loose all these magnetic field lines. They release all of their energy at once. The amount of energy [Laughter] that’s released is ENORMOUS, it’s VAST it’s terrifying!
Pamela: Well and it’s not just energy but these magnetic field lines as they twist and loop out through the surface are filled with plasma and high energy Electrons. The energy is released in the form of both high energy particles as well as in the form of light.
Dr. Plait: That’s right, basically they snap and their energy is blown downward and upward. They shoot particles straight up out of the Sun; they also blast downward and slam into the surface of the Sun. That can generate Gamma Rays which are the very highest form of energy of light. What happens is you get what is called a Solar Flare. It’s just a tremendous flare of energy. It can be several percent of the Sun’s total energy released in just this one little spot.
It’s an explosion that just totally dwarfs the entire nuclear arsenal of the Earth; it’s a tremendous amount of energy. It’s dangerous in two ways one of which is that the Gamma Rays come screaming out of the Sun and those can hit our satellites and they can cause a lot of damage to the satellites.
When they hit the metal of the satellite they basically blast the Electrons off the metal. The Electrons go scattering every which way inside the electronics of the satellite and can fry it.
Pamela: And there’s no warning that this is going to happen because well, light travels at the speed of light so we don’t get a chance to see the burst coming before it lets loose.
Dr. Plait: That’s right so basically the first notice you have of this is when your satellites die and that’s bad. This has happened in the past. We’ve had these Gamma Rays from Flares damaging satellites and shutting them down before.
But then the other problem is that traveling at tremendous speeds is a wave of subatomic particles, Protons, Electrons, Helium Nuclei, what are called Alpha Particles. They come screaming out of the Sun and they can be here in a day or two. Sometimes they’re moving a million miles an hour and sometimes they’re moving three or four million miles an hour. So they come screaming across the Solar System and slam into the Earth.
What this does is they hit our magnetic field and make the magnetic field sort of shake. All the subatomic particles in Space that are trapped in our magnetic field start slithering around like beads on an Abacus I guess you could think of it. The thing is when you do this you generate a huge electric current. That’s the thing to remember.
The details of this are very complicated. The point is a Solar Flare or what is also called a Coronal Mass Ejection which is another type of Solar Event which blasts out huge amounts of subatomic particles, interact with the Earth’s magnetic fields and they generate a HUGE current. They induce a current. Now that induces a current in the Earth’s surface, literally Electrons start to flow in the ground.
Over most of the Earth this isn’t too big of a deal. The problem is in North America – in Canada and the United States – the geography, the geology of the rock is such that you can get these tremendous currents generated there. This can affect our power grid.
In 1989 a tremendous Solar Event actually blew out power grids in the Northeast and in March in Quebec the power went out. Basically our power system was designed way back when to only have a certain amount of electricity flowing on it. In the intervening years we built more cities, more towns, we spread everything out and even though we have not upgraded our system, we’ve let more current flow on it.
If a current is induced by a Solar Event, there’s not as much leeway as there used to be and so in March of 1989 a Solar Event did this to our already maximally loaded grid, dumped a bunch more current into it – like trying to force more water into a pipe that already has as much water as it can bear, the pipe will burst if you do that – so that’s what happened to our grid.
Our grid overloaded, transformers blew out and people in Quebec in March in Canada were without power for 3 days which is BAD.
Pamela: And it’s cold there.
Dr. Plait: Yeah, that’s really bad. That was twenty years ago now and we still haven’t done anything about this. So our grid is even more overloaded and we’re approaching a Solar Maximum. In 2003 we had HUGE Flares coming from the Sun, bigger than anybody had ever measured before since they started measuring them.
If something like that happens again – and we were lucky, none of them was aimed at us, we caught the edges of them – but if one of them is aimed right at us that could blow out the power grid over vast regions of the United States and Canada. If that were to happen again in November or December, or even in the summer when we’re trying to cool our houses and our office buildings that would be a disaster.
Pamela: And it’s a multi-level disaster because you can imagine we get one of these Coronal Mass Ejections that’s pointed straight at the Earth and it’s accompanied by a Flare of Gamma Rays headed toward the Earth, you knock out a few satellites, say cell phone connections. Then you knock out the power grid.
You now have people that have no electricity and no communications. It’s the multi-layered lack of all the things that our modern society has gotten used to having that could just not mass panic not mass death but some death, a lot of inconvenience and severe economic repercussions. That’s the place that we really need to worry.
Dr. Plait: And it’s even worse than that. If you’re an Astronaut in Space, those Gamma Rays can be very serious. They could be strong enough to give you radiation poisoning which would be bad.
Not only that but it affects the Earth’s magnetic field and it means that any airplanes that are flying at the time (for example) if they are using GPS satellites and the GPS satellites go down they could go to compasses but then their compasses and some of their navigational equipment won’t work very well because the Earth’s magnetic field is bouncing around like a super ball.
So, this could be really bad. It’s hard to really know exactly what will happen until it happens. We don’t want to have to go through that to find out. The thing is, like Asteroids, we can minimize this problem by upgrading our grid. We can put in more cables, we can try to insulate them better, there are a lot of things we can do.
The problem is it costs a lot of money. We’re talking billions of dollars to do this. The thing is, at what cost is this? Is it better to insulate things now (and I mean insulate against the disaster) by spending money now or waiting until after it happens losing people and losing billions or even hundreds of billions of dollars of economic growth in business?
Pamela: We never know and so I think this is where upgrading the power grid is definitely something that if anyone ever bothers to ask an Astronomer we probably need to be doing.
Dr. Plait: Right.
Pamela: Let’s see how long it takes the Sun to come out of minimum and maybe we’ll get lucky and have a really boring maximum. Now these aren’t the only ways that the Earth can be destroyed, they’re just the most likely.
Dr. Plait: That’s just chapters one and two.
Pamela: [Laughter] that’s just chapters one and two. So we don’t have time to go into this much depth on all the chapters of your book but what are your favorite ways to contemplate the destruction of the Planet Earth?
Dr. Plait: When I was researching the book, well it was fun. The book is not supposed to scare the pants off of you. I don’t want people lying awake at night panicking. This is more like a rollercoaster ride or a scary movie where after it’s over you, ‘phew’ you feel better, you don’t have to worry about these things so much.
I’ll throw this out there even the most statistically likely event like getting killed by an Asteroid, your chance of being killed by an Asteroid is one in 700,000. Really all of these things as scary as they are, are very low likelihood events. And some of them like the death of the Sun or when we collide with the Andromeda Galaxy and all kinds of disasters can happen then, they will happen but not for billions of years.
The death of the Sun was one of my favorites to write about and to research because even though I knew a little bit about it, I didn’t know the precise timing. I was able to find a timeline of what’s going to happen to the Sun when it swells up into a red giant.
The current thinking right now is that – you know everybody always says the Earth is going to get consumed by the Sun. The Sun will expand out and go past the Earth and we’ll die that way. But in fact, as the Sun starts to expand, the Solar Wind this constant stream of particles coming from the Sun, is going to increase as well. That means that the mass of the Sun is going to get lower, it’s losing mass. If it’s losing mass, it’s losing Gravity. If it’s losing Gravity, its hold on the Earth isn’t as strong.
So, over the next billion years as the Sun is getting warmer, the Earth will very slowly spiral away from the Sun. It’s hard to say right now and there are people arguing back and forth but right now it looks like we’ll just barely escape the Sun. Mercury and Venus, sorry it’s lights out for them. [Laughter] Um but we may make it.
Of course though having what’s essentially a charcoal briquette at several thousand degrees occupy half of your Sky is bad. The Earth will still be toasted it just won’t be totally vaporized. [Laughter] You can be happy about that or not. But one of the reasons I really like this is because I read a paper that said we can actually save the Earth by moving Asteroids around. If you swing an Asteroid past the Earth, the Asteroid gets moved by the Earth. The Earth’s gravity will move the Asteroid. But the Asteroid’s gravity will move the Earth as well.
It’s a variation of the Asteroid Gravity Tug. You can drop Asteroids past the Earth and actually move it out from the Sun. It takes a long time. It might take you know hundreds of thousands or even millions of years but the Sun doesn’t get hot that quickly so you have that much time.
Every few thousand years you can swing an Asteroid past the Earth and it would pull the Earth out. We could actually prolong the life of the Earth a long time by doing this. I thought that is AWESOME. That is such a cool idea. I was really thrilled with that.
Pamela: And that helps prolong the life of the Earth in a lot of different ways. One of the things that we’re looking at is as the Sun gets older it’s going to get hotter and it’s going to do bad things to the planet Earth. This is because as the world gets hotter the oceans begin to evaporate which causes the Planet to get hotter which causes the oceans to evaporate more which causes the Planet to get hotter – it’s this horrible cycle.
If you can find a way to move the Earth further and further from the Sun, it’s a way of compensating for the fact that the Sun is getting hotter. It’s always neat to consider turning your Planet into a spaceship and that’s basically what we’re talking about.
Now there are still other ways that you can destroy the planet. Were there any others that just stuck in your mind as just ooh cool?
Dr. Plait: Well my very favorite far and away is Gamma Ray Bursts. I’ve been studying Gamma Ray Bursts for a few years so that was probably one of the most difficult to research. We still don’t know that much about these events, their total energies and how it all works.
Basically in a nutshell you have a Super Massive Star a hundred times the mass of the Sun. The core of that Star runs out of fuel and collapses. It will probably form a Black Hole and this creates a huge Blast Wave which blows the outer layers of the Star off. So you’ve got like octillion tons of gas expanding outward at some fraction of the speed of light. It generates a HUGE amount of energy and that’s a Super Nova, an exploding Star.
But in the core of this thing, the Black Hole is formed from the very innermost part of the Star. There are just all kinds of things going on there. There’s friction and gravitational energy and magnetic energy and there’s just what I like to call a ‘witches brew’ of Forces.
All kinds of things happen but the end result is that you can focus two beams of energy that come out of the top and the bottom of this thing basically, in two different directions like a lighthouse.
But instead of swinging around, they just go straight out from the Black Hole. They might last a few seconds up to a minute or two. That’s how long this event lasts. But the amount of energy in these beams is beyond human comprehension.
Pamela: [Laughter] It’s a wonderful… there’s more light in that few ten to maybe a couple hundred seconds than the Sun gives off in many lifetimes.
Dr. Plait: Yeah, it’s basically all the lifetime energy of the Sun compressed into a few seconds and I like to tell people this, if it’s a sunny day go hold your hand up to the Sun and feel the energy hitting your hand. Now think about the surface of the Earth compared to your hand and how much energy is hitting the Earth. Now remember that the Earth is only one two-billionth of the sphere surrounding the Earth at the Earth’s distance.
In other words, the sunlight hitting the Earth is only one two-billionth of the amount of light the Sun is putting out. The Sun has been doing this for 5 billion years; it will continue to do this for another 5 billion years. Now compress all of that into 10 seconds, alright. That’s a Gamma Ray Burst. The energy is out of control.
We see these things happening billions of light years away and yet some of them are putting out so much energy that if you were looking at the right spot at the right time you would SEE them! You could stand out in your front yard and ask yourself look at that Star, what was that? That was a Gamma Ray Burst 8 billion light years away. It’s just unbelievable.
Pamela: There’s a chance that we’ll have front row seats to one of these – although it’s not going to be pointed directly at us.
Dr. Plait: That’s right, if you actually calculate how close a Gamma Ray has to be to do physical damage to the Earth – and that sort of damage is usually destroying our Ozone layer, creating a radiation shower or a particle shower in our Atmosphere that can kill you through the radiation. It turns out that they have to be roughly seven or eight thousand light years away. Anything farther away than that doesn’t really hurt us.
It turns out there are two Stars that close. One of them is Eta Carinae or Eta Car as some people call it. You’ve seen this picture; it’s a famous Hubble picture. It looks kinda like a dumbbell. This is a Star that nobody is really sure, has something like a hundred times the mass of the Sun. The thing is when it blows up it may be a Gamma Ray Burst. It may not be but it might be.
But we know it’s aimed the wrong way. We can see the geometry of the system and that beam is going to miss us by quite a bit, by thousands of light years. So even if Eta Car blows up, we’re safe from it. It’s going to be a very bright light in the Sky and probably it’s not going to be a big deal.
But there’s another one called WR104 – it’s got this catalog name – that’s at about the same distance. From what we can tell it’s kinda sorta aimed at us. We don’t know exactly. We don’t know if it’s going to be a Gamma Ray Burst. We don’t know when it’s going to blow up. We don’t know if it’s aimed at us.
All of these things together make me think ah, I’m not too concerned about it. But you know it’s interesting. If it blew up it’s just close enough to do minimal damage to our Ozone layer. If this happened at a time when the Ozone hole was already kinda hurting, this could exacerbate the problem.
It’s not going to kill anybody but you could get a slightly worse suntan. That’s kinda funny to think that an object that’s trillions and trillions of miles away, quadrillions of miles away really, could actually physically hurt you. That’s amazing to me.
Pamela: So we definitely live in a Universe that’s trying to kill us and we’re out of time. So, if people want to learn more, what should they do?
Dr. Plait: Well, they can go to my website, www.badastronomy.com . I’ve written quite a bit about this. Of course, they can buy the book “Death from the Skies” …..
I do want to leave you with one thought. While researching this book I came up with everything I could think of to wipe out life on Earth and I have a pretty vivid imagination. I was coming up with some crazy stuff. [Laughter]
And then I would research and find out yeah, you know this could work. But, I’m not running around in panic. I’m not screaming in circles yelling “the Sky is falling”. The thing is the odds of these things happening are really, really low.
The point of this book is to look at the really cool things that are going on in the Universe. Black Holes and Galaxies are colliding and all of that kind of stuff happening. Have a little fun with it; yeah, you might get a LITTLE scared from this stuff, but you don’t have to worry.
There are a lot more important things in life to be concerned about. We should be at least looking at Asteroid impacts. We should be looking at the active Sun, but everything else you won’t have to worry about too much. It’s just kind of fun to read about them and think about what might happen.
Pamela: Your book is a fun read and it’s been a great pleasure talking to you Phil.