Centuries ago the stars were believed to reside just beyond the planets of our solar system.It never fails to astound me how big the Universe is—how far away even the nearest stars are, let alone other galaxies scattered from here to near infinity….

How do we know how far away celestial objects are? This shouldn't be taken for granted, as it's not as straightforward as sounding the depth of the ocean floor with sonar, or determining the range to an object by bouncing radio waves off it and timing the reflection.

In fact, we have "pinged” the nearest celestial objects with radar to determine their distances very accurately. Examples are the Moon and Venus, where round-trip lightspeed travel is measured in seconds or minutes.

Before radar, the scale of the Solar System had to be determined geometrically, by observing events like Venus or Mercury transiting the face of the Sun from different locations on Earth and triangulating. Even this technique requires telescopes, which we've had only four hundred years. Before that, figuring out distances to just about everything except the Moon was mostly guesswork. In fact, it wasn't too many centuries ago that the entire Universe was believed to be not much larger than the Solar System—the Sun and it's nine…excuse me…eight planets—as we know it today.

Once the distance from Earth to the Sun was figured out, that length (the "Astronomical Unit”) in effect became a basic measuring rod for working out distances to everything else, by one means or another.

As Earth orbits the Sun, the direction from which we see stars shifts minutely, and we can observe a small change in a star's position compared to the more distant "background” stars. You can see the same effect by holding a finger in front of your face and looking at it alternately with one eye, then the other.

The geometry of this observation is a simple triangle, whose base is the distance between your eyeballs and whose legs are the lines from each eyeball to your finger. By knowing the length of the base, and observing the change in viewing angle against the background, the length of the legs (distance from your eyeballs) can be calculated.

In the case of Earth and a nearby star, the "eyeballs” are the Earth at two ends of its orbit around the Sun (six months apart) and the "finger” is the star.

But this measuring of distance by "trigonometric parallax," as it's called, only works for the nearest stars, as the minute shift in the star's apparent position diminishes with distance.

As astronomers learned more about the distance to nearby stars, they determined how to relate their temperature and mass to their actual brightness, and it became possible to estimate the distance of many stars by measuring their apparent brightness, with an understanding of how the brightness of light weakens with distance.

To measure the depths of space between us and galaxies far, far away, in which individual stars are indistinguishable from the overall galactic glow, we can turn to certain types of supernovae: individual stars that temporarily shine brightly enough to be observed and measured. Like the flare of a match struck in the dark night, the brilliance of the flash reveals how far away the striker stands.

We have built up our knowledge of the Universe's vastness over the past couple centuries, working out the problem from the near to the far. Even as science and technology have made the world on which we live smaller, it has done exactly the opposite to the Universe….

There is an awful lot of DNA stuffed into every cell.Ben's blog on stars and grains of sand got me to thinking about DNA. How long would the DNA from every living thing on Earth stretch? Could we make it to the next star? The next galaxy? The end of the Universe?

Let's start out with people. Each human cell has around 6 feet of DNA. Let's say each human has around 10 trillion cells (this is actually a low ball estimate). This would mean that each person has around 60 trillion feet or around 10 billion miles of DNA inside of them.

The Earth is about 93 million miles away from the sun. So your DNA could stretch to the sun and back 61 times. That is one person’s DNA.

The best estimate I could find of the world’s population of people is around 6.7 billion. When we multiply 10 billion miles of DNA by 6.7 billion, we end up with, well, a really big number. Something like 6.7 X 10¹⁹ or 67 quintillion miles. That is too big a number so let’s convert this to light years.

A light year is around 6 X 10¹² miles. So all human DNA would stretch 11.2 million light years. The closest star to Earth (besides the sun) is around 4.2 light years. So we shoot way past that! The Andromeda galaxy is about 2.5 million light years away from us so human DNA could stretch there and back two or three times.

What if we add the rest of the DNA on the planet? It would obviously be much farther but it is hard to calculate because we don’t know how many plants, animals, bacteria, fungi, etc. there are on the planet. We also don’t have detailed information about every species on Earth.

Let's add bacteria to the mix. I decided on this because we know how many cells are in a bacterium—one.

One number I saw was that there are 5 X 10³⁰ bacteria on Earth. Bacterial DNA tends to be a lot smaller than human DNA so there will be less of it per cell. Let's say on average there is 4 million base pairs of DNA/bacterium (this number could be off by a very lot). This translates to around .05 inch of DNA per bacterium which means you need to scrape together around 1.3 million bacteria to get a mile of DNA. So all the bacteria in the world have about 3.5 X 10²⁴ miles of DNA.

How far is 3.5 X 10²⁴ miles of DNA? Well, it is about 640 billion light years of DNA. The end of the observable Universe is about 14 billion light years away. So if we stretched out bacterial DNA it would go to the end of the Universe and back around 23 times. Of course it would be incredibly thin and so actually doesn't take up much space in the Universe.

So that's just human and bacterial DNA. (Well, mostly bacterial since human is so piddly in comparison.) I haven't added all of the rest of the DNA out there. I'll leave that to you.

Are there more actually more stars in the sky, than there are
grains of sand on all the world's beaches?
I think most of us have heard that perennial estimate of the number of stars in the Universe being greater than all of the grains of sand in all of Earth’s beaches.

Sitting on Limantour Beach at Point Reyes awhile back, watching the waves slosh in and out, listening to gulls and feeling very lazy, I found myself looking about me at all that sand, and wondering how it could possibly be true. Reaching out, scooping up a mere handful of grains and letting–what?–a few hundred thousand of the would-be star proxies fall through my fingers, the notion seemed even more absurd.

Raising my eyes from the bit of the cosmos cupped in my hand and taking in the comparatively vast reaches of sand about me–a hundred or so feet between me and the waves, at least a mile or two of beach visible to the north, another stretch to the south, and who knows how many feet of depth beneath the surface? I simply couldn’t believe it. So, I pulled out my journal and started to write down some figures, working out the problem rationally.

So, is it true? Well, here's what I came up with:

Stars: Astronomers have estimated that there are about 200 billion stars in the Milky Way Galaxy. Galaxies come in many sizes, both much larger and considerably smaller than our home galaxy. I don't know what the average number of stars in each galaxy is, but for the sake of this calculation I chose a conservative 10 billion stars per galaxy. Astronomers have also estimated that there are between 50 billion and 100 billion galaxies in the Universe, based on observations made by the Hubble Space Telescope. Again being conservative, I chose the lower figure of 50 billion. So, with those numbers, I calculate a number of stars in the Universe at 10 billion times 50 billion, or 500 billion billion—or in exponential notation, 5 X 10²⁰.

So how does the number of sand grains in the entire world's beaches stack up against that?

To get to that number, I had to do some estimation. First, pulling some numbers out of the air, I decided that an average sandy beach is 30 meters wide (about 100 feet), and 10 meters deep (about 33 feet). Some beaches are wider, some much less so. I don't imagine that the sand on the average beach is as deep as 10 meters—but I've never taken a shovel and found out, either.

Next, I assume that the average sand grain is a millimeter across, giving it a volume of about a cubic millimeter. With that number, I figure the sand grain density to be 1000³, or one billion, sand grains per cubic meter of beach.

The final piece of the equation–after density, width, and depth–is length: the total length of beach shorelines in the entire world. Here's where I made some serious assumptions. Starting with the total length of shorelines of all continents and islands in the world, I got a figure of 356,000 kilometers from the CIA World Factbook. That's 356 million meters.

Now here's where my estimate becomes truly conservative. In my final calculation, I assumed that all 356 million meters of world coastline consisted of sandy beaches– which is not the case, of course; there are plenty of coastlines that are rocky, pebbly, gravely, ice-covered, or sheer cliffs, all without much, if any, sand.

So what were my results? Well, doing the math, 1 billion grains per cubic meter times a 30 meter beach width times a 10 meter beach depth times a 356 million meter beach length and assuming 100% of the coastlines consist of my hypothetical average beach, I get:

1 billion x 30 x 10 x 356 million x 100% = 1.068 x 10²⁰ grains of sand

Compared to the estimate of stars in the Universe, that's about 5 times as many stars in the Universe as grains of sand in all the beaches in the world! I guess the old adage was not only right, but somewhat of an understatement…

But it's all a thing of scale. I also calculated that there are about 3000 times as many water molecules in a glass of water than there are stars in the Universe…

The universe is made of stories.

The Universe Is Made of Stories
I think the central story of Christianity is not one of the parables of Jesus, or even his death and resurrection, but a simple story of a meal shared with friends. The story goes like this: Jesus took a loaf of bread in his hands, blessed it, broke it, and shared it with those around him. This story tells me how to live a good life. If I take each moment as it comes, if I enter into the moment, if I don't hold back, if I share the moment with those around me, then I am living a good life–solving a problem at my job, sharing the road on my way home, sharing dinner with my wife, reading a good novel while she practices at the piano, making love, taking out the trash, and walking the dog.

Religious people argue with atheists and scientific materialists over the existence of God. Agnostics, people who may have a sense of the sacred in their lives, who claim to be spiritual, but not religious, reject any formal organization of religious thought and practice. There is truth in every perspective, but I want to try to answer the atheists and the agnostics. I'll use poet Muriel Rukeyser in my answer to the atheists. She wrote "The universe is made of stories, not atoms." There are scientific stories, such as the Big Bang theory about the origins of the universe, or Sir Isaac Newton's story of a canon ball's trajectory from the mouth of a canon. And there are religious stories like the one I described above. Scientific stories and religious stories are qualitatively different. Maybe scientific stories tell us how things work and religious stories tell us how to live a good life.

In my answer to the agnostics I will use poetry as well. Poetry is particular. Jane Kenyon wrote a poem about a man in a coffee shop eating yogurt out of a container with a white plastic spoon. She could have written about eating in general, but I don't think it would have made a very interesting poem. Religion is particular and interesting, while spirituality is general and boring. Someone who samples a number of religious traditions is still being religious, I think. They just may be missing the benefit of going deeply into any one tradition.

Religious traditions tell different stories about what it is to be human and what it means to live a good life in a particular culture. I wonder if Catholicism would make more sense in Asian cultures if, instead of using bread in the Mass, we used rice cakes. Christianity took root in Latin America only after the Blessed Mother appeared to Juan Diego, a poor peasant, in the form of a "mestiza," a woman of mixed European and American Indian descent. Buddhism, with its story of Siddhartha finding enlightenment beneath the Bodi tree, seems to make perfect sense to many people in the West, and many people in the West find enlightenment and wisdom through the Sufi poet Rumi, an excellent story teller. The central Jewish story of the exodus from slavery in Egypt has had meaning for other oppressed peoples, especially those in Latin America.

I think the universe is made of stories–scientific and religious types of stories. I could not imagine life without either one of them.

Jim Gunshinan is Managing Editor of Home Energy Magazine. He holds an M.S. in Bioengineering from Pennsylvania State University, State College, Pennsylvania, and a Master of Divinity (MDiv) degree from University of Notre Dame.