Tag Archive | "astronomy"

Venus in Transit

Beauty and Beast

And art thou, then, a world like ours,

Flung from the orb that whirled our own

A molten pebble from its zone?

How must the burning sands absorb

The fire-waves of the blazing orb,

Thy chain so short, thy path so near

Thy flame-defying creatures hear

The maelstrom of the photosphere!

–   Oliver Wendell Holmes, The Flâneur


When, in 1882, Venus appeared to pass in front of the Sun’s disc in an event known as a transit, little was known of the planet, except perhaps that it was one of the brightest objects in the night sky (third only to the Sun and Moon) and that it was both the “morning star” and the “evening star”. Much about Venus, and even the Sun, was therefore left to the imagination, and this is what gave the doctor, poet, and amateur astronomer Oliver Wendell Holmes the liberty to write the preceding verse. As can be surmised from Holmes’s poem, which was inspired by his witnessing the 1882 transit of Venus, he imagined the planet – “a world like ours” – to be populated by “flame-defying creatures” who would be audience to the “maelstrom of the photosphere.”

To put Holmes’s romantic visualization of Venus in context, note that in 1882, space probes are yet to be sent to Venus. In fact, space exploration hasn’t begun then. (The world had to wait for nearly three quarters of a century for the first space probe.) The most intriguing aspect of Venus known to scientists at the time of the 1882 transit came from the poet and astronomer Mikhail Lomonosov who, in 1761, discovered that Venus had a substantial atmosphere. But even under the intense scrutiny of generations of starry-eyed telescope users, Venus refused to give up her secrets. Ironically, the same atmosphere that made Venus so alluring, and that made her the brightest object in a moonless night sky, also constantly veiled her from the prying eyes of astronomers. Since her cloud cover never parted, successions of space lovers were given the freedom to imagine what lies beneath Venus’s curtain of vapours. Thus Holmes’s The Flâneur.

Witnesses to this year’s transit of Venus do not have the freedom Holmes had. Such is the price of knowledge. But what we now know about the Earth’s “twin planet” is no tether to the imagination. In fact, as usual in science, reality has shown that our wildest imaginations are barely wild enough to match what’s really out there. After the fly-by mission of 18 space probes, and after 17 landings that lasted only for an hour at most, we now know that Venus is a real-world materialization of the medieval conception of hell; Venus is both beauty and beast. However, let us save the discussion of Venus’s peculiarities for another article. For the moment, let us turn our attention to that surreal meeting of worlds that is an astronomical transit.

Different views of the Venus transit. (Photo credit: NASA.)


Ingress and Egress

An astronomical transit occurs when one heavenly body appears to pass in front of another as viewed from a vantage point, usually the Earth. When the obscuring body covers most or all of the other celestial body, the event is called an occultation.

This Wednesday, June 6, people in the Philippines will have a chance to witness the transit of Venus with the Sun, an event similar to the one that inspired The Flâneur. The last transit of Venus with the Sun was in 2004, and the next will be in the year 2117, followed by another in 2125; transits of Venus with the Sun are rare events that occur in pairs separated by an 8-year gap.

A picture of the 2004 transit of Venus. (Photo credit: excithai.com)

During the transit, Venus will appear as a small dot moving across the disc of the Sun. For more details, see the Appendix of this article or visit the website of the Astronomical League of the Philippines. As viewed from the Philippines, the transit will happen from around 6:00 AM until a quarter to 1:00 PM. However, the precise timing of when the transit begins and ends is very sensitive to the location of the observer. It is for this reason that transits were very important to astronomers. By noting their exact location on Earth, determining the exact timing of the start and end of a transit, and comparing their recorded times with that recorded by other observers, astronomers were able to get a first guess at the distances between the planets and therefore comprehend the nearly incomprehensible scale of the Solar System. (For more on the scale of the Solar System, see this article.)

Another reason why transits are very important is that they help us find extrasolar planets. Extrasolar planets are planets that orbit a star other than our Sun. (Some extrasolar planets do not orbit any star at all, but rather float alone in the cold of interstellar space like a homeless orphan.)  How do astronomers use transits to find extrasolar planets? What they do is measure the brightness of a certain star as detected from Earth. For many stars, the level of brightness is fairly constant. However, for some stars a brief period of slight decrease in brightness is detected at regular intervals. This brief dimming can be caused by an orbiting planet undergoing a transit across its mother star.

Even the brightness of the Sun as measured from the Earth’s surface will decrease by a very tiny bit during the transit of Venus, as Venus is partially blocking the rays falling into Earth. The decrease in the Sun’s brightness, however, is very small because Venus is very small compared to the Sun.

So transits of Venus are important and rare astronomical events. Of course many of us want to witness this occurrence, which is why we now discuss the ways of viewing the transit safely.


Viewing the Transit

There are several ways to view this year’s transit safely. The easiest way would be to buy glasses with solar filters. Such glasses are also called eclipse glasses because they also allow you to view solar eclipses without damaging your eyes. Another material that can be used, according to the Astronomical League of the Philippines, is a welder’s glass graded #14.  A word of caution: do not look through materials of questionable quality. When you have old solar filters or welder’s glass that are scratched or had their quality compromised in any way, do not use them. If you are in doubt about the ability of a material to protect your eyes, do not look through it. Finally, do not buy “eclipse glasses” from people who do not know their astronomy. The transit of Venus is a must see, but you do not want it to be the last thing you’ll view.

Glasses with sun filter. (Photo credit: transitofvenus.nl)

Another way to view the transit is through a pinhole projector. The simplest way of making a pinhole projector is to get two sheets of paper. (Yes, it can be as simple as that!) One sheet of paper will have the pinhole, a small hole measuring around 1-2 millimetres in diameter. The other sheet of paper is where you will project an image of the Sun. To project an image unto the second screen, orient the first screen such that the Sun’s rays hit it directly (that is, so that the rays are perpendicular to it). Next, place the second screen behind the first. So that you could see the projection on the second screen, place it in a dark place. Adjust the distance of the second screen until you obtain the sharpest projection. Below is my pathetic attempt to illustrate the simplest kind of pinhole projector.

The simplest kind of pinhole projector.

Another, slightly more sophisticated way of making a pinhole projector is to make a long tube (which can be made of cardboard or some other material). Both ends of the tube are covered. However, one end will have a pinhole (1-2 mm) punctured into it. To view the projection at the other end, make a window large enough for you to see the projection. Longer tubes are better. Lengths usually suggested are 6 feet and 1 meter. Below is an illustration of the tube projector.

A second type of pinhole projector.

A third way of viewing the transit is by projecting a magnified image of the Sun. For this you’ll need a telescope (either a monocular or a binocular), a projection screen as usual, and simple cover to cast a shadow unto the projection screen. By directed the telescope towards the Sun, a magnified image of the Sun is projected onto the screen. To see this dim projection, use the cover to cast a shadow unto the screen. Below is an illustration.

How to make a magnified projection of the Sun.


Happy Viewing!

Given the historical significance and rarity of the transits of Venus, I am sure many of you would want to witness this year’s transit for yourself. Just remember, your eyes’s health must still be top priority.

And who knows, your witnessing the 2012 transit might inspire you to pen down your own verse in the same way that Oliver Wendell Holmes was inspired by the 1882 transit.



* * *


There are four important events in a transit, and astronomers have special names for them. First comes what is called first contact (or ingress I), when the disc of Venus as seen from the Earth first makes contact with the disc of the Sun. In the Philippines, this will happen at around 6 in the morning. Next comes what is called second contact (ingress II), when Venus is, for the first time, totally within the yellow orb of the Sun. Second contact will come about 27 minutes after first contact. At around 12:30 at noon comes third contact (egress I), when the black dot that is Venus begins to leave the Sun’s face, a process that will be completed come fourth contact (egress II), around 18 minutes after third contact. The precise timing of these events was used by previous generations of astronomers to determine the scale of the Solar System.

Detailed map of the 2012 transit of Venus. (Credit: Fred Espenak)

Also, here’s a link to the live stream of the transit.

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How to Become a Black Hole

The Biggest Sucker

So, do you want to suck big time? What I mean is, do you want to be a black hole? You’re in luck, because this guide will teach you some of the basic tricks on how to be one of the biggest suckers in the universe!

But before we turn our attention to actually becoming a black hole, let us first start with the fundamentals. Let’s begin by talking about what two blokes named Newton and Einstein said about this thing called ‘gravity’.


Why I Am Attracted To You

Legend tells us that a fellow named Isaac Newton was inspired to formulate his theory of gravity when he saw an apple falling (not very far) from the tree. The truth of this story is not that important; what’s important is that Newton’s supposed observation made him realize that the same force that made the apple fall towards the ground also made the Moon go around the Earth! In fact, this is the same force that keeps the planets in orbit around the Sun, and that keeps the Sun and all the other stars of the Milky Way Galaxy in orbit around the galactic center (which is probably home to a gigantic black hole, but let’s not get ahead of ourselves).

As a matter of fact, Newton said that everything in the universe that has mass pulls towards it every other thing that has mass. In short, everything with mass attracts everything else with mass! This means that I am attracted to you, gravitationally speaking. After all, you and I both have mass. And yes, you are attracted to me too (gravitationally, of course, and perhaps otherwise). And yes, there’s also mutual (gravitational) attraction between myself and this nearby bottle of wine, and between myself and the binary star Sirius 8.3 light years away.

Newton: a science big wig.

Yes, I know, Newton’s idea sounds loony, to say the least. But, like most crazy-sounding ideas in physics, it comes with an equation that has proven effective for centuries. This equation is:

 F = (G *m­A*mBd2

Here, F stands for the strength of the gravitational attraction between two objects A and B. On the other side of the equation, mA stands for the mass of A while mB stands for the mass of B; d stands for the distance between A and B and, finally, G is a number called the universal gravitational constant. We’ll get back to G later. For now, what’s important is that the equation above was proven true for hundreds of years after Newton wrote it down. More importantly, Newton’s simple equation explained so many different things, like why gravity is weaker on the Moon than on Earth, why the planets move around the Sun in elliptical orbits, and why angry birds shot from a sling follow a parabolic path.

You attract me...gravitationally.

But then the question arises: why don’t we feel our mutual (gravitational) attraction? If you have mass and I have mass and what Newton said is true, then where’s the love? The explanation lies with the number G in the equation above. The thing about G is that it’s a pretty small number. As a matter of fact, it is given by

G = 0.00000000006673 N m2/kg2,

which is miniscule indeed. Because G is so small, the strength of gravitational attraction between everyday things and between ordinary people (i.e. people aside from yo mama) is negligible. Let me give a specific example to illustrate this point. Say, person A has a mass of 50 kg and person B, who stands 1.0 meters away, has a mass of 60 kg. According to Newton’s equation above, the force of (gravitational) attraction between A and B is given by

 F = ( 0.00000000006673 N m2/kg2)*(50 kg)*(60 kg)÷(1.0 m)2

With a little help from a scientific calculator, the answer comes out to be around 0.0000002 newtons. (‘Newton’ is the measure of force in the same way that ‘meter’ is the measure of length.) An ant’s bite is many, many times stronger than 0.0000002 newtons.

To feel the strength of gravity, you need a really massive object like the Earth. For example, a person with mass 60 kg is attracted to the Earth with a force of around 600 newtons. If you want to know just how strong 600 newtons is, try lifting a 60-kg person.

Newton’s equation for the strength of gravity stands as one of the greatest achievements of any human mind. But there’s a tiny problem with Newton’s theory of gravity. Although it knows how gravity behaves, it doesn’t explain why there’s gravity at all. Why should everything with mass attract every other thing with mass? Why should the Earth pull us towards it? To these questions, Newton’s theory had no answer. We had to wait for some other bloke named Albert Einstein to supply us the answer.


Messy Hair, Neat Mind

Nearly two hundred years after Newton’s revolutionary theory of gravity, a Swiss patent clerk named Albert Einstein made the equally revolutionary theory that basically states that space and time should not be treated as distinct entities but should be united in an entity called ‘spacetime’. This theory is called the special theory of relativity, and it is where the world’s most famous equation, E = mc2, comes from. What Einstein’s famous equation basically says is that mass (m) can be converted to energy (E). The quantity c is the speed of light, which is a little more than 1 billion kilometers per hour (nearly 300 million meters per second).

Central to special relativity, as the theory is also called, is the fact that nothing with mass can travel through space faster than the speed of light. In other words, the speed of light is the speed limit of the universe. Only light can go as fast as 1 billion kph, and no signal can go faster.

However, Einstein has not yet solved the riddle of gravity in his special theory of relativity. He had to struggle for 10 more years before he finally come up with his general theory of relativity, which stands as one of the finest products of human thought. In general relativity, as it is also called, Einstein explained that gravity is the curvature of space and time (that is, of spacetime). Massive objects, Einstein explains, warp the fabric of space and time around them, and this warping is what we observe and experience as gravity. So yes, spacetime has curves too, and everyone is attracted to these.

The universe has curves too -- and everyone's attracted to them.

The example is best illustrated by imagining a horizontally flat bed sheet that is held tout. Think of this bed sheet as the fabric of spacetime. When it is empty, spacetime is flat. When you place small things on this flat fabric, they stay where they are – there is no gravity. Next, imagine placing a bowling ball on the fabric. Notice how the bowling ball changes the shape of the fabric so that now, if you place small things on the fabric, they ‘gravitate’ towards the bowling ball – the bowling ball pulls the small objects toward it, which is basically what gravity is all about!

Attraction. There's the gravitational kind and then there's the other kind.


Now, Off To Black Holes!

Now that we know what gravity is (it’s the curvature of spacetime) and that it gets stronger as objects become more massive, we are almost ready to study the requirements that we must pass to become a full fledged black hole. But before we do, let us first look at some of the distinguishing characteristics of black holes.

When one fellow going by the name Karl Schwarzschild tried to solve Einstein’s equations, he noted that one solution described an object with very peculiar properties. One of the more amazing properties of this object is that it had a gravitational force so strong you need to travel faster than light just to escape its pull. But remember that nothing can go faster than light. Not even light could go faster than light! This means that when something gets too close to this object, they get sucked in and there is no escaping. Not even light can escape it! For this reason, such hypothetical object came to be called ‘black holes’. They’re called ‘black’ because they suck even light. And they are the universe’s biggest suckers! They suck everything from subatomic particles to stars.


The Standard Procedure

We are now ready to answer the question: how does one become a black hole? Well, here’s how.


1. Be a star. And don’t be just any star, but be a really massive one. A star like our Sun won’t do. To be safe, be a star that is around 20 times more massive than our Sun.


2. Die. Living stars are happily glowing orbs of plasma. That’s not what we want to be. We want to be black holes, and to be one you must be a dead star.


3. Furthermore, aspiring black holes like ourselves must follow the proper procedures when dying, which are listed as follows:

a. When you’re old, be a red supergiant. Red supergiants are among the biggest stars in the universe.

b. After becoming a supergiant, be a supernova. Supernovae are really bright explosions; they occur when a massive star reaches the end of its life. How many stars are there in a typical galaxy? Around billions. Even if you combine the brightness of all of these stars, a supernova is brighter still.

The Lives of Stars

c. Don’t be a neutron star. Many big stars retire to become neutron stars. But neutron stars don’t suck. Instead, they are just very dense (like most people). In fact, neutron stars can be so dense that a glass full of neutron star can be heavier than a skyscraper!

d. If you followed procedures a, b and c when dying, then congratulations, you are now a black hole! Go suck away at the universe.


The Short Cut

Let’s face it, not all of us can be stars. Luckily, there’s a short cut one can follow to be a black hole. Even better, it can be expressed in one sentence.

Be very, very dense.

But recall that density is a measure of how compact an object is. To be dense is to have a lot of mass packed in a very small volume. Mathematically, density is mass divided by volume.

To be as dense as a black hole, you must do either of the following:

1. Be really massive. However, you must do this without getting bigger. If you gain as much volume as mass, that won’t increase your density. How massive? If you are a person 5’ 7” tall, you must increase your mass to 1.6 million billion billion kilograms. That’s about 27 times the mass of the Earth. Good luck with that!


2. Here’s another option: compress yourself to a very small ball. For a person who masses 55.0 kg, you’ll be a black hole if you are compressed to a ball of radius 0.000000000000000000000000082 meters. That’s actually a lot smaller than a hydrogen atom. Again, good luck with that.


3. The easiest way to be a black hole is to be massive and small at the same time. Consider the Earth. It’s a pretty massive thing, isn’t it? Well, to make it a black hole, you simply have to compress it to a ball with radius 8.8 millimeters. The radius 8.8 millimeters is called the Schwarzschild radius of the Earth. If you compress anything to a ball the size of its Schwarzschild radius, it becomes a singularity – in other words, a black hole. The Schwarzschild radius of a 55-kg person is 0.000000000000000000000000082 meters while that of the Sun is about 3 kilometers.


Additional Guidelines

Here are additional guidelines on how to be a happy, sucky black hole.

1. Rip space and time. Black holes are singularities. Singularities are regions in space and time where the curvature of spacetime becomes infinite. Using our fabric analogy earlier, black holes are regions where the fabric of space and time has a rip.

When the universe is ripped, you get a black hole.

2. Don’t be naked. There is a hypothesis called ‘Cosmic Censorship’ that says that naked singularities don’t exist (with the possible exception of the Big Bang singularity, which partly explains its name). Singularities, according to this hypothesis, are always “concealed” by an event horizon, so that they are not visible to the rest of the universe. The event horizon of a black hole is the “surface of no return.” Since nothing that goes through the event horizon ever goes out, this means that anything that happens inside the event horizon will remain unknown to the rest of the universe.


3. Be hairless; black holes have no hair. What this means is that black holes have very few features. To describe a black hole, you just need to know its mass, its electric charge and how fast it rotates. If you have two black holes with the same mass, electric charge and speed of rotation, then you have no way to distinguish one from the other.


4. Be very disorderly. In physics, disorder is measured by a quantity called entropy. A very messy room has a high entropy while an organized room has low entropy. According to a principle called the Second Law of Thermodynamics, the entropy of an isolated system has a very strong tendency to increase with time. That is why you have to exert a lot of effort to keep you room neat and tidy but you don’t need to exert any effort at all to put it in disarray. Now, black holes are known to have very high entropy. As a matter of fact, they’re among the most disorderly things in the universe!

How do we know that black holes are very disorderly? It has something to do with the fact that disorderly systems are easy to describe. For example, how do you make a disorderly room? Just throw stuff around the place! How do you stack a random deck of cards? Just place any card on top of another without fussing which card is which. Orderly systems, on the other hand, are really difficult to describe. How do you fix a room to make it orderly? You have to put everything in its right place — the couch goes here, the table goes there, this painting is to be hanged here, and so on. How do you stack a deck where the cards arranged in increasing order? You have to put the aces first, then the ones next, then the twos after them, and so on.

Now, remember that black holes are hairless, which means that black holes are really easy to describe, which means they are very disorderly.


Happy Sucking!

So there, your very own guide to be a major sucker. I hope that helped a lot in your aspirations to be one of the universe’s most curious objects. Now it’s time for you to go away from me — I don’t want to be sucked in just yet.


Photo credits:

  • ffden-2.phys.uaf.edu
  • cse.ssl.berkeley.edu
  • astronomynotes.com
  • imagine.gsfc.nasa.gov
  • eastpdxnews.com
  • blogs-images.forbes.com

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Walking Through Our Solar System

Year of the Solar System

It's the Year of the Solar System!

Happy Year of the Solar System! The planets are so happy to greet you they decided to move too close to each other just so that they could fit in a family portrait to show you. Also, so as not to dwarf their smaller siblings, the giants of the family had to move a lot farther from the camera.

Shown below is a more candid family portrait. Here, the planets are shown in their correct size relationships.

All planets great and small. (I know, Pluto should not be there.)

But how far are the planets with respect to each other? When I taught high school astronomy two years ago, I tried to draw a Solar System that’s to scale on our classroom’s white board. Good luck to me! I ended up either trying hard to include Jupiter in my drawing or attempting to carefully draw the crammed orbits of the inner planets just so that they’re distinguishable from each other. In the end, I used a number of steps to illustrate the relative distances of the planets to each other. (“If the Sun were here, then Mercury would be so and so paces away.”)

Before we go to the relative distances involved in our cosmic neighborhood, let us first have a word about the units we use to measure the Solar System.


Measuring the Solar System

The average distance of the Earth from the Sun is about 150 million kilometers. If you could fly to the Sun in a spacecraft that travels at three times the speed of sound, it would still take you more than 5 years to get there! So that we don’t have to be inconvenienced by humongous numbers in describing distances within the Solar System, astronomers invented the astronomical unit (AU). 1 astronomical unit is equal to 150 million kilometers, the average distance of the Earth from the Sun.


How Many Steps from the Sun?

Using the astronomical units, the distances of the planets from the Sun can be written in convenient, sizable numbers. These numbers are shown in the table below.

 Planet Average orbital radius (AU)

















The second column is labeled average orbital radius because a planet’s average distance from the Sun is indeed the (average) radius of its orbit.

Now, let us make our mini Solar System. Imagine the Sun to be where you are right now. (Better yet, imagine you are the Sun.) If you take 4 steps from your current position, you’d get to where Mercury is. To get to Venus, you have to take 7 steps from where you are, while you need to take 10 steps to get to the Earth. Meanwhile, you need to take a good 15 steps to get to Mars’ obit. So far, so good.

But wait, notice that to get to Jupiter, you need to take no less than 52 steps! Jupiter, it turns out, is more than three times as far from the Sun (that’s you) as Mars is. Why is there so much empty space in between Mars and Jupiter?

Well, as most of us know, the space between Mars and Jupiter is far from empty. Rather, the space is populated by a swarm of rocks called the asteroid belt. Some of the asteroids are so large they are considered dwarf planets. Many scientists think that they are rock fragments that failed to coalesce into a planet during the Solar System’s formation because of the constant gravitational tug of neighboring Jupiter.

But don’t imagine the asteroid belt to be a densely clustered group of flying rocks. Although the asteroids number by the hundreds of thousands, there’s plenty of space for them to distribute themselves in.

Asteroid Belt

Now let’s go back to our walk through of the Solar System. We learned that if the Earth is 10 paces from the Sun, then Jupiter is 52. Meanwhile, Saturn would be 96 paces from the Sun. Saturn is nearly ten times as far from the Sun as the Earth is! About twice as far out, at 192 paces, is Uranus. (No, I will not make a Uranus joke). Neptune, the farthest planet (yes, get over it), is 301 steps from the Sun.

As I am writing this, I am in a room whose biggest dimension is around a hundred steps (that’s “how far” Saturn is from the Sun). When I place textbook on one corner of this room (the “Sun corner”), I can hardly see it from the opposite corner (the “Saturn corner”). However, from the Sun corner, the positions of Mercury (4 steps), Venus (7 steps), Earth (10 steps) and Mars (15 steps) are literally within spitting distance. I highly doubt it if I can spit as far as the orbit of Jupiter (52 steps).


The Ends of the Solar System

Don’t worry, I did not forget about Pluto. Just because astronomers do not consider it a major planet anymore doesn’t mean I stopped loving it.

Before we “walk to” Pluto, let me first get this out: nothing “happened” to Pluto. No, it did not become a moon of Neptune. It did not even shrink. Above all, it did not become a star!

If you’re wondering why I had to say this, good for you. Many people – and I mean many – believe that something happened to Pluto to deserve its “demotion” from being a major planet to being a dwarf planet. And yes, some people think it became a star. (Well, in a sense, it became a ‘star’. But you know what I mean.)

Pluto and its twin, Charon, from the surface of Nix. Pluto's third moon, Hydra, is also within view.

I think the misunderstanding surrounding Pluto’s planethood (or stardom) reveals the natural human tendency to be essentialists. In other words, most people still think that to be a planet, one must have the essence of a planet – one must possess planetness. That truth, however, is that ‘planet’ is just another word for ‘biggish object orbiting a star’. In this case, the star is our Sun. And we get to decide how big is big. The problem with Pluto is not just that it’s really small, it’s that we found at least one other object orbiting the Sun that’s bigger than Pluto. That object is Eris, named after the goddess of discord and strife. Along with Pluto, Eris is part of the Kuiper Belt, a second belt of rocks orbiting the Sun. Most of the Kuiper Belt lies beyond the orbit of Neptune. Other members of the Kuiper Belt have names like Sedna, Xena (the warrior princess), Makemake and Haumea.

Eris and its moon, Dysnomia.

Artist's impression of the Kuiper Belt (courtesy of Don Dixon)

Now, let’s go back to our walk through. Recall that in our mini Solar System, you are the Sun. 10 steps away is the Earth, 52 steps is Jupiter and 301 steps is Neptune. Pluto is, on average, 395 steps from you. The Kuiper Belt starts at around 300 paces. To get to where Eris is, you have to walk 1,000 steps from where you are. If you think the Solar System ends there, then you couldn’t be more wrong. The Oort Cloud, a hypothetical body of rocks and comets, is no less than two thousand times farther from the Sun as the Earth is. That means that if the Earth is 10 steps from you, then the Oort Cloud is 20,000 steps away! Some astronomers even think that the heliopause, which could be thought of as the outer boundary of the Solar System, is no less than 500,000 steps away. The inner planets are indeed in the innermost part of the Solar System.

Oort Cloud


That concludes our overview of the vast dimensions in our own cosmic neighborhood. I hope the “walk through” inspired you to make a mini Solar System in your own backyard. And I hope that the next time you look up to the heavens, you will see the grandeur that held thrall all the great minds throughout the ages.


Photo credits:

  • www.nasa.gov
  • www.solarsystem.nasa.gov
  • www.universetoday.com
  • www.wikipedia.org
  • www.cosmographica.com
  • www.theiamfamilyoflight.com

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Hey, Ophiuchus

It all started when a newspaper in Minnesota published an article informing the public that they had to say hello to their new personalities.

It had, for some reason, gone viral. If you’ve been a good citizen of the internet lately, news of grand zodiacal realignment may have already reached your screen. Not only is there a shifting of the dates of the astrological signs, but a dark horse sign comes along. Just what is going on here?

From Wikipedia: an illustration of axial precessionThe Earth undergoes several quasi-periodic movements, including rotation on its axis and revolution around the sun. Of the many planetary motions*, axial precession is largely to blame for the change in zodiac signs.

Axial precession is the cyclical change in the orientation of a planet’s rotational axis. The rotational axis would more or less trace a small circle at the end of a cycle. Notice that the entire rotational axis of the earth would trace out a cone. If you happen to have a top right now, go ahead and spin it. Precession is the wobbling motion that becomes very obvious once the top is about to fall.

For the earth, precession is an extremely slow process, and the time it would take for its rotational axis to completely trace a circle would be about 25,772 years. Thus, the position of the stars that we see at night relative to where we see the sun in the sky changes gradually.

When Western astrology was first introduced by the Babylonians, the signs were based on which constellation the sun crossed when it rose**. Over the course of three thousand years, axial precession has caused the background stars to shift, leaving us with shifted zodiac dates as well. Perhaps Bill Nye can explain it better:

If this is the case, why then did the astrological system last as long as it did? Did astrology suddenly decide to drop its central dogma?

Astrology, like many other belief systems, branched out into different systems over time. Although we now have a multitude of ways one can interpret one’s birthday, we can group most of these astrological systems into either tropical or sidereal.

The tropical system is the most common twelve sign system with fixed dates for the signs. This is because it is based on the location of the equinoxes and solstices in the calendar. Though precession changes the dates of the equinoxes and solstices (which are dependent on the orientation of the earth’s rotational axis) slightly, it is corrected for during leap years***, and so the dates more or less remain constant.

The sidereal system uses the original system, and determines the zodiac sign based on what constellation the sun crosses upon rising. What the astrologer was mentioning on news were the mechanics of the sidereal system, which was being practiced by some astrologers all along.

Well that explains the shift in the dates, but what of Ophiuchus?

The sun had always been crossing Ophiuchus, even during the time when astrology was first written down. The sun would intersect with Scorpio and Ophiuchus for about eight days each, before to moving on to Sagittarius. Having thirteen signs was rather lopsided and awkward, and was difficult to properly match with other archetypes such as elements. So the Babylonians decided to eschew Ophiuchus and keep Scorpio, probably because Scorpio look more “aligned” with the other signs.

Several western astrological systems do use Ophiuchus though, further splitting the Sidereal system into either one that incorporates Ophiuchus or one that ignores it.

This recent zodiac sign crisis was no doubt a result of sensationalized media and distortion of information augmented by the force of the internet. Perhaps we should learn a bit more before taking the media’s word, or before heeding random predictions about behavior based on arbitrary shapes from a changing mural of stars.

An illustration of Precession and Nutation*Other planetary motions related to precession that could influence the ecliptic** include nutation and polar wander. Nutation is a repeated “nodding” of the earth, and causes the rotational axis to trace a circle with “frills” instead of a smooth circle.

Polar wander is when the geographic north pole, and therefore the south pole, slightly changes its position. Both these motions are very small and slow, and only make noticeable changes over a long time. There are many more quasi-periodic movements that the earth undergoes, and collectively these are known as the Milankovitch cycles.

From Wikipedia: The Earth in its orbit around the Sun causes the Sun to appear on the celestial sphere moving over the ecliptic (red), which is tilted on the equator (blue).

**The apparent path the sun takes across the sky as we see it from here on earth over the course of one revolution is called the ecliptic. In other words, the constellation that the ecliptic intersects with on that date is that day’s appointed zodiac sign. The ecliptic lies in the ecliptic plane. In the image to the right, The large red circle is the ecliptic.

The ecliptic gets its name from the fact that when the moon intersects with the ecliptic, an eclipse would occur. (if the moon gets in front of the sun’s path in the sky)

***Our leap days are there to correct how long it takes for the earth to revolve one period around the sun, which is approximately 365.25 days. This is known as a sidereal year. Due to planetary motions such as axial precession and nutation, we would notice that the dates and positions of the equinoxes and solstices would change, and therefore we would slowly see the seasons come earlier and earlier in the year. This would be rather disorienting for humankind, when snow starts falling in Japan in June. The effects of precession and nutation are corrected for, however. This explains the existence of an additional rule in determining leap years, where all years that are multiples of 100 are not leap years, unless they are multiples of 400. On average, the time it takes to get from one summer solstice to the next is about 365.242 days, slightly shorter than the sidereal year. This is known as a tropical year.

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How David Hume’s Critique of the Design Argument Survives for Three Centuries (Part 2)

(Continued from Part I)

Chaotic Universe

More recent findings in astronomy, for instance, substantiate Hume’s assumptions of a chaotic universe rather than an orderly one. Astronomers contend that the universe used to be crowded and disorderly; stars were more massive as they die rapidly and detonate after millions of years. These explosions result to newer and heavier elements, spawning new stars, less massive, but multiplying amidst chaos. Stephen Hawking, in his book “A Brief History of Time”, explains that the universe is congested and limited in extent, with no beginning or end (1988). However, many of us assume that the orbits of stars and planetary bodies take defined movements which have been ‘properly spaced’ so as moving matters in space may glide in ‘safety.’

Conversely, for many billions of years, planetary objects have been traveling in changing paths and orbits, consequently colliding and crashing onto each other. The ‘order’ we perceive now as we gaze at the stars is just a result of planetary bodies which toppled obstructive matters off their paths. Surprisingly, these orbits were random, as astronomers assert that the elliptical course is the most dangerous of all paths. Most collisions in the universe result from aberrations in shape, path or movement.

The Dangers of an Ellipse

If design were intelligent as god applied it to his ‘creation’ of the universe, a circular orbit is safer for a celestial body to move across space. “If all the orbits were nearly circular,” scientist Rolling T. Chamberlain affirms “only a few of the separate bodies moving in them would come into collision with one another” but because the orbits take an elliptical shape, conflicting much in contour and dimensions, particles in space have high prospect of colliding against each other (2001). Stars do not just return to their original positions in space due to the infinite movements of heavenly bodies as the stars and other matters disperse into interstellar space. This results to the thinning out of the universe in which stable orbits do not subsist. Likewise, Hume reiterated that the universe has no a semblance at all on complex human made machines as artifacts are designed for a purpose. On the contrary, the universe has an unclear function (Poidevin 1996). While on the surface the universe may seem to suggest order, it is difficult to surmise its apparent function. The famous biologist J.B.S. Haldane once replied to a reporter who queried what his research on genetics suggested about the deity. Haldane replied that “He must have an inordinate fondness for beetles,” referring to the numerous species of these insects existing for no perceptible function other than for the purpose of reproduction.

Defying Anthropomorphism

Hume also showed us that it is apparently easy to compare things found in our world and yet, we have nothing to compare our universe to as it is the only one we know that infinitely exists. Thus, it defies logic to compare a whole to a part of a whole and vice versa. We may perceive a god present in the universe at all times, but this comparison does not provide scientific value. It is remote that theology and other social sciences can actually benefit from it. Hume emphasized that the analogy between the minds of humans and the mind of an omniscient being is ‘anthropomorphic.’ Nature in general is mindless rather than ‘intelligent.’ It is credulous to interpret the mind of god using the human mind as an equivalent.

As the product of an anthropomorphic philosophy always results to a close look at the finite god, Hume demonstrates through his propositions that if the argument from design is seriously considered, most of us will come to the conclusion that the god who controls the universe entirely differs from the concept of the god/gods of organized religions. As there has been a dearth of valid arguments on how all- knowing and perfect the designer is, we have to assume his abilities and traits manifested in the universe he designed and created. Bertrand Russell, one of greatest thinkers of the previous century, summarized these attributes and capabilities in a more telling fashion, ‘If I had millions of years of time and infinite power and had come up with the universe as we know it, I should be ashamed of myself.”


Chamberlain, Rolling T. (2001) “The Origin and Early Stages of the Earth,” in The Nature of the World and of Man, p. 37.

Gaskin,J.A.C. (1779). Dialogues concerning Natural Religion in: Dialogues and Natural History of Religion, ed. (Oxford & New York: Oxford University Press, 1993). Page references are to this edition.

Hawking, Stephen (1988). A Brief History of Time. Bantam Books. ISBN 0-553-38016-8.

Hume, D. (1739-40) A Treatise of Human Nature: being An Attempt to introduce the experimental Method of Reasoning into Moral Subjects in two volumes

Norton, D. F. (1993). Introduction to Hume’s thought. In Norton, D. F. (ed.), (1993). The Cambridge Companion to Hume, Cambridge University Press, pp. 1-32

Poidevin, Robin Le. (1996). Arguing for Atheism, (New York: Routledge,), p. 85.

Sober, Elliot. (2003). “The Design Argument” p. 27-54 in (Manson 2003).

Swinburne, Richard. (1991). The Existence of God (NY: Clarendon)

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How David Hume’s Critique of the Design Argument Survives for Three Centuries (Part 1)

That the universe is designed by an ‘intelligent creator’ as it exhibits balance and order has prevailed for centuries as the ‘most robust argument’ in defense of theism in the philosophical realm of old. Even in the present century, theists recurrently invoke the classic Design Argument as proof of god’s existence. This argument was torn down, however, when David Hume put forward his criticism of the Argument of Design – a treatise that sparked further acerbic debates for many centuries on the subject of god’s existence (Gaskin 1993). Although many attempted to dispute his arguments, the sagacity and decisiveness of Hume’s critique, until today, are difficult to challenge.

Cleanthes vs. Philo and God’s ‘Work of Art’

The “Critique of the Design Argument” is presented in Hume’s book Dialogues Concerning Natural Religion in which he puts forth a discourse between fictional characters, Cleanthes and Philo. The discourse begins when Cleanthes brings Philo’s attention to the world around them, asserting that the world is but one great machine, with its tiniest parts attuned to each other and with accuracy worthy of admiration and contemplation (Gaskin 1993). Cleanthes further adds that the creator’s ‘larger faculties’, parallels the minds of men as they manifest wisdom and intelligence and thus, it is only logical that an intelligent ‘maker’ shaped them (Swinburne 1991). This argument, Cleanthes believes, ‘proves the existence of a Deity’.

Using the house and the universe as analogy, Philo asserts that the universe does not show any relationship to a house as this is a flawed logic. The universe is a manifestation of nature while the house is man-made as he emphasizes the complexities we fail to clarify in the works of nature. Philo contends that men’s capability to understand ‘infinite’ relations is inadequate and it is “impossible for us to tell, from our limited views, whether this system contains any great faults” or merits any justifiable adulation when “compared to other possible, and even real systems” (Hume 1739).

Through Philo’s character, Hume contends that order and purpose are perceived only when they are the consequences of design. However, we see some kind of order all the time manifested in seemingly unconscious occurrences like vegetation and generation. Thus, design constitutes only a tiny fragment of our perception with regards to ‘purpose’ and order. Assuming that the design argument is feasible, Hume argues that it is not enough to surmise or prove the existence of a deity from the conclusions gleaned from our knowledge of the universe’s configuration which bears a distant resemblance to human design – cursory and sometimes unintelligent – a world which Hume states is “the only and the first rude essay of some infant deity, who afterwards abandoned it, ashamed of his lame performance” (Hume 1739).

Hume believes that god’s intellectual or mental order and faculties need to be understood in order for the design argument to be decisive and reach a logical finality. Otherwise, we could not create a parallel explanation of order, or actually define it, leaving the notion too arcane and inscrutable. Hume also argued that if an orderly and balanced natural world necessitates a special maker or designer, then God’s mind as it is well ordered, likewise requires a creator. Thus, this maker would similarly need another maker, and so on. The comparison with nature and the various things found in it, Hume adds, is ineffectual as things present in the universe are set apart from human material items as they exhibit considerable disparity (Hume 1739).

The Degradation of the Creator

Cleanthes further argues that ‘the works of nature bear a great analogy to the work of art (Sober 2003) insisting that the resemblance which exists between this world and human products is quite significant. Hence, god is somehow ostensible in human intelligence. Hume argues that this leads to a degradation of the creator. He suggests that we know nothing about the nature or the attributes of god as everything about the deity is unknown and there exists only a distant analogy among the diverse operations of nature. These comparisons do not suggest that the basis of the emergence of the universe is the mind or human intelligence. The aforementioned analogies, according to Hume are so feeble and distant that god’s nature cannot be explained nor understood (Poidevin 1996).

An Argument against All Odds

For a many decades, Hume’s treatise has been challenged using modified arguments from the intelligent design proposition. Scholars in the field of religion and philosophy have concocted innovative extensions borne out of the design proposition. These counter-arguments however, fell apart as Hume’s critique stands robust amidst attacks from different schools of philosophical thought.

Hume’s arguments persist until today as his objections to the prevailing idea that an orderly universe exists are strengthened and supported by science. Although knowledge of the universe during Hume’s time is not as advanced as of late, Hume exhibited deeper understanding of the universe we live in.

To be continued…

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