The Moon and Life

There are many analogies for the likelihood of life spontaneously arising from the primordial soup of early Earth. Dropping Scrabble letters onto the floor and having them arrange themselves into a Shakespearean play. A hurricane passing through a junkyard and leaving a fully assembled 747 in its wake. All things to try and express how unlikely our DNA actually is.

However, there is something that stacked the odds in the Earth's favor - the Moon. But how could the Moon affect the development of life on Earth?

We see the effects of lunar gravity today in the form of tides. Today the tides are relatively tame and usually aren't very destructive. However we can see today that the Moon is slowly spinning away from us. As it orbits around the Earth, the Moon moves ever so slightly away every year.

If you think of gravity like a rope tying the two bodies together as they move through space, the Earth would slowly be letting loose more rope. It isn't fast enough to make any difference on a human timescale. But in the billions of years that the Earth and Moon have been doing their celestial dance, the difference has been quite large.

Just as it is moving further away today, in the past the Moon must have been much closer. Since the Moon was closer, its gravity was stronger, and so the tides would've been much larger.

What difference does that make though?

The tides behaved like a blender, mixing up the primordial soup in the early Earth. The tides would raise and flow over an outcrop, and when the tides recede there will be pools left over. When these pools evaporate, the concentration of the various chemicals and molecules in the water increases. Repeated countless times, over thousands and millions of years.

Each time one of these pools form, it is like dropping a bag of Scrabble letters. If you do it long enough, you'll get Hamlet. Could life develop without a Moon to mix things up? Probably.

Would it have taken much longer? Most definitely. So next time you look up at the Moon, think about how something so far away is directly responsible for the fact that you're standing there looking at it.

The Steam from a Boiling Pot

I have mentioned previously on my blog that most of what astronomers 'know' are not really facts. In astronomy we have few direct observations, and then assumptions based on them and indirect observations we can make of stars and galaxies.

This is a paper I've written on the subject dealing with some research that I've done. It shows that sometimes even the most obvious, basic assumptions we make can be wrong.

Open publication - Free publishing - More research

Seven Threats in Heaven

As promised, here is Seven Threats in Heaven, an examination of seven of the most challenging obstacles that face humanity in the attempt to colonize space. It discusses factors such as creating artificial gravity (which is required for the human body to function properly in space), ways to protect the colonists from cosmic rays and solar radiation, and how to produce food for a population in space.

It is the first of many Astronomical Intelligence articles, hopefully. The presentation style appeals to me - it is professional enough to sooth my ego while being easy enough that I don't tear my hair out trying to get it to work.

Leave a comment if you'd like to see more of these kinds of articles!

Living in Space

If humanity really does damage the environment of Earth to the point that it is no longer suitable for sustaining us, we will have to find alternative places to live or we'll very predictably die. Most likely this would involve creating underwater/underground cities - self enclosed and self sustaining. But if we managed to completely destroy the Earth, where would we go?

Space is logical. We have put several space stations in orbit, after all. What would you need?

For a substantial population to live for an extend period in space, you'd need:
1. A substantial supply of water, and a way to recycle water that is used.
2. A renewable source of electricity.
3. A way to produce Earth-like gravity for the population.
4. Farming facilities - probably hydroponic farming.
5. Protection from solar/extra-solar radiation.
6. A sealed atmosphere, and a way to filter any contaminants. Farming would provide a way to
7. A way to collect needed materials that you can't produce.

A simplified list certainly - but I plan to go into more detail in the future. Check back later for the Astronomical Intelligence's Guide to Living in Space.

How much do we actually know?

It isn't a question that you see asked much, which is in a way more worrying to me than any wrong assumption people might have. The world isn't a science fiction movie, but for all intents and purposes it doesn't matter. Just because the way black holes are portrayed in movies, and so how most people think about them, is wrong doesn't make a difference at the end of the day.

However I think the title question is something that does matter, and it should be asked more often. How much do we know about the universe?

The truth is, we don't actually -know- much at all. The blog title is more than a coy, arrogant reference to my own perceived level of knowledge. It is also a bit of an in-joke about how much we can say for sure that we know about the world around us.

We can't do experiments on other stars or other worlds (outside our solar system). We can't make the universe repeat itself so we can see if thing happen the same way every time. All we can do is watch and make observations. Then we make assumptions based on those observations.

We look at the spectra of stars, and see it looks very much like spectra from the Sun. They are massive, bright, hot objects. We can tell all of that from looking at stars. So we assume that they are like our sun. But we can't say for sure. We haven't gone up to another star and done tests on it. All we can do is make observations of the stars we can see.

So far, they all appear to behave similar to the sun. But even if we look at billions of stars, or trillions of stars, there is nothing to say that the next one won't be something completely different. It's happened before. What we thought were stars at one point turned out to be distant clusters of thousands of stars, or galaxies, or even Blazars, giant jets of energy released as the 'last gasp' of matter falling into a black hole. They all looked like stars until we started looking harder. With better instruments, better detectors, with better resolution.

We very well could be wrong again.

Astronomical Intelligence Audio - Episode 2

This week on Astronomical Intelligence Audio, I talk about what gives stars their power. More specifically, I talk about fusion and how you actually obtain energy from it. I hope you enjoy and find it informative. If you have any further questions, leave a comment and I'll do my best to answer it.

Terra-forming Mars

This is a personal pet peeve of mine that I'm asked about quite often by my friends and family: So when are we going to build cities on Mars?

It. Will. Never. Work.

Not in the way that people would imagine it to work. For those of you who don't know, terra-forming is the process of making another planet or moon Earth-like. It's something that you see in science fiction quite prominently, and it is often applied to Mars.

Not to go into it too deeply, Mars would seem to be a good candidate for terra-forming because all that is needed is for it to warm up and to increase the atmospheric pressure. Currently the atmosphere on Mars is very thin, and so the air pressure is very low.

If you've ever looked at the instructions on a cake mix or other recipes, you may have noticed separate directions for high altitude areas. This is because the atmosphere is thinner the higher up you go, and so the air pressure is lower. Liquids both expand and boil much faster when there is less pressure.

Your body is 70% water. Think about that for a minute.

So increasing air pressure is a must. It is also so cold on Mars that carbon dioxide can freeze, which forms most of the Martian polar caps. That is too cold for any human habitation, so the planet needs to warm up as well. I've just given an obvious answer to both problems though.

There is a large amount of carbon dioxide locked into the polar caps and in the soil of Mars. Carbon dioxide is a very good greenhouse gas, as you've probably heard from the debate on global warming on Earth. That is what we need to do on Mars - global warming. Increasing the amount of carbon dioxide in the air would increase the atmospheric pressure, and the greenhouse effect would warm up Mars.

If there is one thing humanity knows how to do, it is put carbon dioxide into the atmosphere. So what is the problem?

Mars can't hold onto an atmosphere. It used to have a thick atmosphere, and the conditions were right for water to flow on the surface. We can tell because of various clays we observe in the Martian soil which require there to be water for a substantial period to form. However, these regions are billions of years old.

Mars is much smaller than Earth. It's interior cooled much more rapidly. Think of a chicken nugget. After a short time, a chicken nugget will cool off from being cooked. A chicken breast though, after the same amount of time the center will still be warm. The same is true of planets. It is more complicated than that, but the premise is the same.

The cooling interior means that there is no molten core, like on Earth. We currently believe that the Earth's molten core, or rather the rotation of hot metals in the core are the source of the planet's magnetic field. When Mars cooled, this motion stopped and its magnetic field went away.

Without that magnetic field to deflect high energy particles, the atmosphere of Mars was blasted by the solar wind. This slowly stripped the atmosphere of Mars, and Mars doesn't have enough gravity to hold onto an atmosphere anyway. So the Martian atmosphere disappeared.

If we put a new atmosphere on Mars, the same things will happen again. And Mars will end up exactly like it is now.

So, at least in my opinion and with my understanding of science, any settlements on Mars would have to be enclosed in some way. Avoid the losing battle of trying to stick an atmosphere on Mars.

Pluto - Why isn't it a planet?

This is a question that I've had several people ask me, and one that I've heard discussed numerous times. There is a lot of confusion about -why- Pluto is no longer considered a planet, and no one really went through the trouble of explaining it to the general public. Here is my attempt to spread some truth.

Pluto is no longer a planet because, for a very long time, we had no definition for what a planet really was. Before telescopes were constructed, the planets were Mercury, Venus, Mars, Jupiter, and Saturn. Once we developed telescopes, we discovered Uranus and Neptune and for a while, those were the planets.

However, it was suspected that there was another planet beyond Neptune, because of anomalies in Neptune's orbit. When we were observing it move around the sun, the orbit of Neptune didn't seem to fit what we had predicted, as if there was something else further out in the solar system pulling on it.

This was called 'Planet X', which would explain the anomalies in Neptune's orbit and become the ninth planet. This was the great mistake scientists made that led to Pluto becoming a planet, then being stripped of that status. We didn't find an object and then decide it was a planet. We went looking for a planet and found an object.

There is no large body beyond Neptune. The anomalies in its orbit were found to be because the instruments being used to make the measurements weren't very accurate. Pluto was found by random chance, and even after it was found it was considered odd. It didn't fit into either category of planet.

It wasn't a giant ball of gas like Jupiter, Saturn, Uranus and Neptune. But neither does it really fit in with the terrestrial planets Mercury, Venus, Earth and Mars. Pluto is much less massive than the terrestrial worlds but much more massive than the largest asteroids. Combined with its location far in the outer solar system, it was set apart and somewhat outside our understanding of the structure of the solar system but remained a planet because there was no other classification for it.

The discovery of other objects in the outer solar system complicated the issue. Now Pluto was not an isolated anomaly, but apart of a larger system of Trans-Neptunian Objects. Pluto in particular is apart of the Kuiper Belt, a ring of rocky, icy objects past the orbit of Neptune. If it was the largest object beyond Neptune, it might have remained a planet but there are objects just as big or larger than Pluto, like the dwarf-planet Eris.

That is when the International Astronomical Union (IAU) decided to step in. What they did was to give a somewhat standard definition for what a planet is. In order to be considered a planet, an object has to:

1. Orbit the sun

2. Have enough mass to form itself into a sphere (massive things like Earth have enough gravity that large 'bulges' or bumps get smoothed down, literally crushed by their own weight until the surface is basically a sphere).

3. Have enough gravity to 'clear out' its orbit.

Pluto fails the third requirement. What does that mean?

The eight planets are all massive things. Their gravity is very influential to objects in their immediate area. Take for example Earth. There are no other objects that share an orbit with Earth besides the Moon. Other objects cross Earth's path, but by and large the area around Earth's orbit is empty.

Earth has enough gravity that everything that was in its 'planetary neighborhood' was either pulled in by Earth's gravity or knocked into another orbit. It has cleared out its orbit.

Pluto is in the Kuiper belt. There are objects that share its orbit, and none of them have enough gravity to really clear it out. However, Pluto does satisfy the first two requirements so it is a dwarf planet.

Why did they change it?

The definition created by the IAU is arbitrary, but now at least there is a definition. It was decided that losing Pluto as a planet was acceptable, because any definition that included Pluto would also have to include 44 other objects - all dwarf planets under the current definition. Having eight planets is more palatable to astronomers than 52+. In the end that is what the deciding factor is.

Never accuse astronomers of wanting to memorize things.

Astronomical Intelligence Episode One - Black Hole Formation

Just a quick explanation of how black holes form, and what they are at their core.



The real trick to black holes is wrapping your head around the concept of nothing. More specifically, something being so heavy that it crushes itself. You might have seen where buildings collapse when their foundations are worn away and damaged. That is an adequate description of what happens in a black hole, only the foundations are atoms. Once something is so heavy that it crushes those, then nothing can hold it up anymore, literally. Then it crushes itself to nothing. It's a little hard to conceptualize, as there is nothing on Earth that is similar. But try thinking about this: A trash compactor takes a lot of trash and crushes into a conveniently sized cube. Now imagine that every time it ran the trash compactor crushed the trash into a smaller cube, until finally the trash will be in a single point, like a dot on a piece of paper.

That's basically what happens when a massive star dies. But instead of a hydraulic pistons, it is crushed under the weight of clouds thousands of miles thick, with several times more mass that is in our sun. The core collapses into a single point, and there is enough weight to break apart the very atoms that make up the core of the star. Its like cutting out the support and foundations of a building: there is nothing left holding it up, so the building collapses into nothing.

Except in this case, there is nothing left when the collapse is done.

Before we move on...

Black holes are interesting, but I'm ready to move on so I can cover what I feel like at that moment. I'll deal with one last thing before I go on to something else though.

One thing that many people think when they hear 'black hole' is that if it is a hole, what is at the bottom? A seemingly logical question, and really the fact is that we don't know for sure. We have theories and models that explain what we observe, but we can't actually -test- anything. Any probe or signal we send into a black hole won't ever come out, so we can never really know what goes on at the center.

But lets say you jumped into a black hole to find out what was at the bottom. Would you ever reach a bottom? Could it open into somewhere else?

Both are possible, but really irrelevant. You will never see the bottom of a black hole. Recall earlier that gravity is proportional to the -square- of a distance. Meaning if you are twice as close to something, you experience -four- times the gravity. This means that, amongst other things, your feet are actually being pulled by gravity stronger than your head is, because your feet are closer to the Earth's center of gravity. However, the difference on Earth is so small that it is negligible.

Consider a black hole though, with gravity many times stronger. If you jumped into a black hole feet first, you would slowly begin to feel the gravity at your feet become stronger at your head. This means that your feet would start falling faster than the rest of your body, because gravity is pulling on them more.

You would eventually start to feel stretched as the difference between the gravity at your feet and your head grows stronger. You would slowly start to physically stretch out, your body being ripped apart from the difference in gravity. Eventually you'd stretch into a macabre noodle, as if you were the rope in an astronomical tug of war. This is what we call spaghettification, where your body is pulled into something very much like a spaghetti noodle.

So, who's hungry?

Race to Oblivion

Black holes are formed when the mass of a star is such that when the star finally runs out of fuel that the weight of the star causes the core of the star to collapse. Just like a building collapsing one layer at a time, large stars go through several steps as they desperately try to support themselves. However, unlike a building when the collapse finally reaches the foundation (in the case of a massive star, this is a solid ball of neutrons. One giant atomic nucleus), a star keeps collapsing until there is nothing left. Nothing can support the collapse once it begins.

Electrons are forced to merge with protons to form neutrons.

Neutrons are forced together into a solid mass, until finally they are crushed. With nothing else to support the star, the collapse of the core continues until a black hole is created. All the mass of the core crushed into a singularity, a point that is infinitely small.

The true definition of oblivion.

Black Hole Blowout - Part 1

Black holes are amongst the most misrepresented of all phenomenon in science, both because scientists don't entirely understand Black Holes and because scientists tend to do a bad job of describing what exactly a Black Hole is. Scientists have actually oversimplified the situation in their haste to reduce the huge complexities that black holes represent to something the public can understand, to the point that they are not actually describing black holes anymore.

The standard scientific one-liner to explain Black Holes is generally along the lines of "a black hole is an object which has gravity so strong that not even light can escape it." This is technically accurate, however it implies things that are simply not true.

First and foremost is the idea that black holes have stronger gravity than other objects in the universe, that they act as stellar vacuum cleaners sucking up everything around them. To give an example, imagine this: What would happen if the sun was suddenly and instantly transformed into a black hole of equal mass?

The statement that "black holes are objects that have gravity so strong that not even light can escape them," implies that the planets would get sucked in because the black hole's gravity would be stronger than that of the sun and pull everything into it.

However if the sun was replaced with a black hole of equal mass, the planets would not be sucked into it. In fact, the orbits of the planets would not be affected at all, and the solar system would continue as it always has, albeit much darker and colder without the sun providing energy.

So, a black hole does not possess any more gravitational strength than any other object of equal mass. Yet, it also possesses gravity strong enough to prevent light from escaping. How is this possible? To understand this apparent contradiction, it is necessary to talk about gravity in general.

The attractive force of gravity between two objects is expressed by this equation: Where Fg is "Force of Gravity", M and m are the respective masses of each object, and G is the gravitational constant, a universal constant intrinsic to everything that determines how strong gravity is. Now, r^2 is the distance to between the objects' center of masses.

Now, the center of mass for an object is fairly simple. Lets take the sun as our example.

Now, keep in mind that all matter attracts all other matter individually. What this means is the top of the sun is trying to pull the Earth towards it, while the bottom of the sun is trying to pull the Earth towards it, and so on.

Imagine that every single part (Whether you want to think of regions like top/bottom, or individual atoms) of the sun has its own rope that it is using to pull on the Earth.

Now, think of these 'gravity ropes' as vectors, as in the image below:





The advantage of thinking about gravity in terms of these vectors, at least for the time being, is that it simplifies very well. As you can see, each vector has a horizontal component and a vertical component.

Now, since the sun is (mostly) spherical, there is an equal amount of matter at the top, bottom, left, right, and everything in between. What this means is that the vertical components of these vectors tends to cancel out, like so: This leaves only the horizontal components, which pull the matter directly towards the sun. The center of the sun to be specific, because no matter what direction you move towards the sun, gravity will always pull you directly towards it. The fact that some matter is further away from you is countered by the fact that the same amount of matter is closer to you, giving a center of mass at the center of the object.

So why is this important? As it turns out, in objects like stars or planets, the gravity is strongest at the surface of those object. As you read this, you are feeling the strongest pull that the planet Earth can put on you. If you move away from Earth, you are increasing the distance between you and the Earth's center of mass and the strength of gravity becomes less. But if you move down into the Earth, you are reducing the distance between yourself and the center of mass and so gravity should get stronger right? Remember, that all matter attracts all matter individually. Right now, on the surface of the Earth, all of the matter is pulling you down towards the center of the planet. However, once you are underground, two things change. First, you have less matter pulling you down and second, you have matter above you which will be pulling you up, as this picture shows:


And now we can correct one of the biggest misconceptions about black holes. They possess no more gravity than another object of the same mass. However, black holes are singularities, meaning that you are never 'inside' them. All of the matter is always pulling you down, no matter how close to it you are. The gravity always gets stronger, and this allows something with the same amount of mass to have more powerful gravity effects.

So, describing a black hole as a vacuum cleaner is not accurate. It does not 'suck things in', any more than what other objects do. Rather, black holes are the stereotypical cranky old men that won't let you get basketballs/baseballs out of their yard.

So long as you keep your distance, black holes are no different than any other object. But once you get too close, you never get a chance to learn from that mistake.

Asteroid Fields

I have been asked by friends and family how we get probes and satellites through the asteroid belt that lies between Mars and Jupiter. The simple answer is that, contrary to Star Wars and other science fiction portrayals of them, asteroid fields are rather... empty.

Now, we don't know exactly how many objects are in the asteroid belt. It isn't particularly important for this demonstration, so lets err on the side of caution and say there are 10 million asteroids more than half a mile across in the asteroid belt. How likely are you to run into one passing through the asteroid belt?

The middle of the asteroid belt is around 2.8 astronomical units from the sun. One astronomical unit is 92,955,887.6 miles, the distance between the Earth and the sun. Some quick math (circumference tells us that the circumference of a circle with a diameter of 2.8 astronomical units is 1.64 * 10^9 miles. Written out, that is a circle 1,640,000,000 miles around. If there were 10 million objects larger than half a mile across, there would be 164 miles between each one. And this is if every object was arranged on a ring. The real asteroid belt is a 'donut', a full astronomical unit across, and it isn't completely flat. There is just so much space and so little of everything else that actually running into -anything- is very unlikely.

The odds of succesfully navigating the asteroid belt are significantly better than 3720 to 1, in any case.

Parsecs Part Two: Parallax

This a continuation of the original post here.

Now that we have an understanding of how arc is measured, we can talk about parallax. Parallax is the phenomenon that astronomers use to determine how far away an object is. Although parallax sounds impressive, it is actually something that people deal with every day without thinking about it.

If you've ever looked out the window while riding in a car, you probably noticed that close things appear to be going by faster than things that are further away. The reason why is obvious, if something is 10 feet away and you move 5 feet, you've made a major change in the distance between you. Conversely, if something is a mile away, that same 5 feet doesn't change much at all.

This same principle works for stars as well. Most stars are so far away that it doesn't matter what we do, they don't seem to move at all relative to one another. This is like looking at 2 objects, one which is 10 miles away and 1 which is 11 miles away. Moving ten feet doesn't change the relative position of the two objects at all. They look just as close to one another as they did originally.

However, some stars are close enough that we can see them move ever so slightly. Astronomers take an observation of a star's position in the sky, then wait six months. In six months, the Earth will have moved to the other side of the Sun along its orbit, giving us the greatest change in perspective possible. This turns out to be just enough for us to see nearby stars move relative to the 'background stars'. The picture below is exaggerated, but it illustrates the point.

First, an Astronomical Unit is defined as the distance from the Earth to the Sun. Although not useful for interstellar distances, AUs are convenient for expressing distances within the solar system, such as the distance between planets. In a form that might be more familiar to you, 1 AU is 92, 955, 886.6 miles.

So the 'baseline', or the distance between the two observations is over 180 million miles. This is quite a step up from moving 5 feet to get a different perspective! However, the distances we are comparing this shift to also increased many times over. Proxima Centauri, the closest star to us after the Sun, is about 4.2 lightyears away. A quick refresher, a lightyear is the distance that light will travel in a year. Since light travels at 186 thousand miles a second, the distance it covers over the course of a year is hard to visualize. Without going into scientific notation, a single lightyear is around 5,880,000,000,000 (or rather, just shy of 6 trillion) miles long.

Needless to say, even 'nearby' stars aren't really close in the conventional sense and even the 180 million mile 'step to the left' we make in our orbit around the Sun isn't really significant compared to the huge distances between stars. Still, we have been able to see some nearby stars move relative to the background stars. Proxima Centauri, as our closest neighbore, moves the most of any star.

We now get to the reason why I did the background explanation of arc and what an arcsecond is. Relative to the background stars around it (which are much to far for the movement of the Earth to make any effect at all), Proxima Centauri moves about .77 arcseconds. That means that its position shifts less than 1/3600 the width of your pinky at arm's length!

With precision instruments and a clear night sky though, astronomers can measure that shift. We call the shift parallax. Proxima Centauri has a parallax of .77 arcseconds.

And now we can answer the original question about parsecs. A persec is the distance an object would have to be in order for it to have a parallax of 1 arcsececond. That means that it is close enough that as we move around the Sun, it appears to move 1 arcsecond relative to the background stars. This distance is about 3.26 lightyears. Why don't we just use lightyears then?

Although physicists have a good reputation for being very intelligent people, the truth is they are also human and like to avoid complicating things when they can. Converting a parallax to parsecs is very easy:

Distance (In parsecs) = 1 / Parallax.

Simple and easy to remember. So for Proxima Centauri, 1/.77 = 1.29 parsecs. Multiply by 3.26 to convert the parsecs to lightyears and you get about 4.2 lightyears.

Now in defense of Han Solo, it was later 'clarified' (rationalized after the fact) by one of the later Star Wars novels that he was in fact meaning distance. He was referring to his ship's ability to skim close to black holes along the 'Kessel Run' without getting sucked in, cutting distance off the trip. Not what was originally intended, but it doesn't change the fact that the use of the parsec is wrong even when used in this context.

So a contest for you. I've already explained why the original use of parsec, as a measure of time, is incorrect. If you leave a comment telling me the other reason that using a parsec in this case is incorrect, you get to ask a question and I will give it top priority.

A hint, as it may not be obvious. There is a problem with using parsecs -at all- in Star Wars.

Parsecs Part One: Background

If you've ever seen the original Star Wars, you'll no doubt remember Han Solo's famous boast about the Millennium Falcon, "It's the ship that made the Kessel Run in less than twelve parsecs." This usage turns out to be incorrect for two reasons.

But before we get into that, some background information is needed. The name "parsec" is unfortunate, as it sounds like a fancy science-fiction term for "part of a second". As it turns out, parsecs do relate to seconds, but not seconds of time. It refers to seconds of arc.

Now lets talk about what a 'second of arc' is. Hold your hand out as far as you can and look at your pinky finger. At arm's length, your pinky is appears to be about 1 degree in width. There are 360 degrees in a circle, so if you copied your pinky 360 times you could make a loop around yourself at arm's length.

Each degree is divided into "minutes of arc", or arc-minutes. There are 60 arc-minutes in1 degree of arc. So looking back at your pinky, an arcminute is 1/60 of that width.

Finally, each arcminute is further divided into "seconds of arc", or arc-seconds. There are 60 arcseconds in an arcminute. At arm's length, that means an arcsecond is a mind-boggling 1/3600 the width of your pinky.

Now that we have our background information, we can discuss what a parsec actualy is here.