Science & Nature Archive

Tuesday, April 10, 2012

A 3D Model of the Solar System

Solar System 3D Model Isometric ViewSpace is big. I've written about it before, but that was about distant galaxies. But even when you look in what's supposed to be our own 'neighborhood', the solar system, the distances involved are staggering. I don't think most people have a sense of scale of the solar system, such as how big the Sun is compared to the Earth, or how far it is between the planets. So, I did what any nerd with access to a 3D drafting program would do - I modeled it. And once I had it modeled, I figured other people might find it interesting, so I'm sharing it.

To explain the model a bit, I went to Wikipedia and looked up the diameters of each of the planets (all 8 of them - sorry Kuiper Belt objects), and their distances from the Sun. I averaged out their distances so that I could draw the orbits as circles instead of ellipses - not perfectly accurate, but it still gives a good idea of the sense of scale. I put all that into a spreadsheet, and then divided everything by 1,000,000, to get it in sizes that would work in Solidworks. And keep in mind that Solidworks deals in inches by default. So for example, instead of drawing the Sun at 864,900 miles in diameter, I drew it at 0.8649 inches in diameter. The Earth, instead of being 92,956,050 miles from the Sun, was drawn at 92.956 inches from the Sun. And the biggest distance, Neptune's distance from the sun, instead of being 2,798,310,157 miles from the sun, was drawn at 2798.31 inches from the Sun.

Actually, just stop and think about those numbers. If the Sun was less than an inch in diameter, the Earth would be almost 8 ft away (the standard height from floor to ceiling) and only .008" in diameter, while the most distant planet, Neptune, would be 233 ft away (23 stories).

Anyway, here's the model, in two different formats, along with that Excel file that I mentioned.

That first format is Solidworks. It's the better of the two 3D formats, but you need the right software to view it, and Solidworks isn't cheap (a couple thousand dollars a license - so not really for home use). The second format is an eDrawing. There's a free viewer that you can download. The third file is the Excel file. It has a few more ways of scaling that just what I discussed above, which should be pretty obvious from the text.

Here are a few images taken from the model. Each image has been scaled to fit on the blog. If you click on it, you'll get the full size version.

This first picture is the Sun and all of the planets - Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. It's tough to see the inner planets (Mercury through Mars) because they're so tiny. They look like little more than a smudge in the image below, but they're a bit easier to make out if you click on the full size version. The vertical line just to the left of the terrestrial planets is the center of the Sun. In the model, all of the planets are aligned. The image below was made by first looking straight down all of the planets, then rotating the model just 0.04ยบ so that you could see each planet without it being obstructed by any other planet. Another way to think of this is that it shows the planet sizes to scale, and shows the distances properly relative to one another.


This next one is the same view as above, except zoomed in on the terrestrial planets. Again, the tick mark on the left shows the center of the Sun. You can see the Moon in front of the Earth (our Moon is the only moon I modeled).


The next three images are a kind of series. They're looking 'down' at the solar system from outside the ecliptic plane. To me, these really gets across sense of distance. The first is zoomed in to just the Sun and Mercury's orbit. The second one zooms out a bit to show the orbits of all the terrestrial planets. The third zooms out to show the orbits of all the 8 planets.

So first, here's the Sun and Mercury. Mercury's so small that it gets lost in the curve showing its orbit.


Next, here's the Sun and the terrestrial planets. You can still make out the Sun as a sphere and not just a point. The little tick mark at the Earth is because Solidworks shows tick marks at the center of all circles, and I drew a circle there to show the orbit of the Moon around the Earth. But even that orbit's too small to see at this scale.


Third, here's the Sun and all the planets. Zoomed this far out, even the Sun becomes just a point. You can really see just how far away the outer planets really are.


And finally, here's our own backyard - the Earth and the Moon. It kind of gives a sense of scale of just how far the Appollo astronauts went.


To me, this does help to put into perspective just how big the Solar System is. When you look at the farthest humans have ever traveled - to the Moon and back - and then see how even that distance gets lost in the immensity of the Solar System, it makes you feel tiny. And then when you consider the vast distances between stars and across galaxies - I just can't even wrap my head around it.

Anyway, have fun playing with the model.

Friday, March 9, 2012

Science and Engineering Indicators 2012

NSB LogoEvery two years, the National Science Foundation comes out with a report on Science and Engineering Indicators, detailing the state of science and engineering in this country, including public perception and understanding. The latest report is out at Science and Engineering Indicators 2012. Since 2004, I've written a short blog entry each time on that public understanding part (2004, 2006, 2008, & 2010). I'd always known that people didn't understand science well, but I was amazed at just how ignorant the population is.

Per my usual approach, I've reproduced some of the data from the section on public understanding of science. This year, however, I'm presenting the tables using an image format (I'm tired of fighting the formatting to make an HTML version fit). If you want an actual HTML version, you can find them here: Tables in HTML Format

This first table shows the U.S. compared to other nations. Honestly, the U.S. doesn't stack up so bad. Other than the questions that contradict a literal interpretation of Genesis, the scientific understanding of U.S. citizens is on par with those of other countries.

It's worth noting that the questions are organized a bit differently this year (separated between the physical sciences and the biological sciences). There was also a new question on cloning that hadn't been asked in years past. And two questions that were dropped a couple years ago to some attendant controversy have been brought back - the questions on the big bang and human evolution.

Science and Engineering Indicators Comparison Between Nations

This next table is something that had been included in previous years' reports, but I couldn't seem to find it this year. So, I made it on my own. Below that is a graph of that same data, making it a bit easier to see the trends. All in all, nothing much has changed since they started doing these surveys. The only two questions that have shown significant variation over the years are 'The universe began with a huge explosion' and 'Antibiotics kill viruses as well as bacteria'. The big bang question only appears to have changed significantly due to an exceptionally high number of correct answers for the first year for which data is provided (54%). Since then, it's held steady at about 1 in 3 people getting it right. The antibiotics question showed a trend of significant improvement for many years, but seems to have plateaued in 2006 at 56% - the next two reports after that show a slight decrease.

Science and Engineering Indicators U.S. Trends

Science and Engineering Indicators U.S. Trends

Since nothing much has changed, I'm just going to quote my conclusion from two years ago, instead of trying to think of something new.

"Just look at those results - around a quarter of Americans think that the Sun goes around the Earth, half don't realize that electrons are smaller than atoms, and half don't know that it takes a year for the Earth to go around the Sun! Keep that in mind whenever you hear people citing public opinion polls on the validity of concepts like global warming or evolution.

"It's always a bit depressing to see those numbers. It's hard to believe that the people of our nation are so ignorant. If there's one lesson to take away from these results, it's that we need to vastly improve our education system."

Wednesday, February 29, 2012

What Is a Year

February 29thI don't often just post a link to other people's articles, but this is one that's so interesting and relevant to today, that that's what I'm going to do.

Today is February 29th, a day that only occurs every four years. If you know a bit about how the solar system works, you probably think you understand the reason for a leap year - the Earth's orbit around the Sun is just a little over 365 days, so we need an extra day every so often to get the calendar back in sync with the Earth's orbit. But in fact, that's not the full story. The measurement we use for the length of a year is a bit more complicated than that, and doesn't actually result in the Earth being at quite the same position relative to the Sun year after year. To understand why, go read this article from Phil Plait at Bad Astronomy:

Another orbit? Why, you don't look a rotation older than 4.56 billion years!

And if you want to know a bit more about leap years, and why they occur every four years, but not on some years divisible by 100, but on years divisible by 400, then go read this article of his:

Why we have leap days

Monday, February 13, 2012

Darwin Day & a Quick Announcement

Darwin's BirthdayYesterday was February 12th, the 203rd birthday of Charles Darwin, and the day designated to celebrate Darwin Day. So, happy belated Darwin Day. I didn't post anything special this year just for Darwin Day, but there's plenty of evolution related content on this blog if you just look for it.

And now for the short announcement. I've been neglecting some of the maintenance on this blog for too long. I notice that if you click on the Skepticism and Religion category, you get an error. There are also some things I'd like to do that I can't figure out how to do with Movable Type 3.2, but which seem to be standard with newer versions. So, I'm going to update the Movable Type software running this blog. Hopefully it goes smoothly and the site is never down. But just in case, this is your warning.

I'll see everybody on the other side.

Tuesday, January 31, 2012

Local Church Misunderstands Evolution - Why Are There Still Apes?

My wife spotted an interesting message on a sign out in front of one of the churches here in town. So, she took a picture of it and texted it to me.

Church Sign

For anyone that can't download images, here's the message.


I've been seeing this as a parody of creationists for so long, that it's almost a bit surreal to see someone actually using it seriously. And it's not just some random commenter on a blog, but the message a church is putting out to the public. Even if the sign person at the church has enough freedom where the message doesn't have to get approved by someone else first, my wife tells me that the message has been up for over a week - plenty of time for someone in the congregation to say something about it.

I could just point and laugh at the sign, which may even have been enough for this entry, but that's not very productive. So, while I've covered this on the blog before, since the prior coverage was brief, I'll go through again explaining why this question sounds silly once you actually understand evolution. Since I have covered this before, some of the content below has been copied copiously from a previous post.

One of the easiest ways to see the error in this line of thinking is to use an analogy. I'll use myself as an example. My great great grandfather and grandmother on one side were German - not just of German ancestry, but born in Germany and immigrants to the U.S. So, I can quite literally say that I am descended from Germans. But it's also quite obvious that I'm not descended from any living Germans. A certain group of Germans and I share a common ancestry through my great great great grandparents. The descendants of my great great great grandparents split into two lineages - one that continued in the U.S., and one that continued in Germany. That lineage in Germany is composed of my cousins, not my ancestors.

Another way to see the error in this line of thinking is to pose it with a different group of animals. It's a bit like asking, 'If crows evolved from birds, why are there still birds?'

It's a very similar case with us and chimpanzees and bonobos. Around 6 million years ago, there was a population of apes that was neither human, chimpanzee, nor bonobo. Over the generations, this population split into multiple lineages, each of which evolved independently. Most of those lineages have gone extinct, but there are still three of us left. We are cousins. We can go back further in time and find the ancestor that we share with gorillas, and further to find the ancestor we share with orangutans, and on and on all the way back till life began. None of those ancestors will look exactly like any of their modern descendents, since evolution has been occurring in all of the lineages. (Obviously, we haven't actually found fossils of all species that have ever existed. But, in the same way that you know you must have a great great great great great great grandmother, even if you don't have any record of her, we also know that we must have common ancestors with Earth's other organisms, even if we haven't yet found their fossils.)

I think there's another misconception associated with this assertion. I think it goes back to the Great Chain of Being, where people feel that evolution is directed, and that us humans are the pinnacle. That's not the case. Much of the change that occurs in evolution is through mutation and natural selection (though those aren't the only drivers). Mutation is random. It just happens, without any conscious intent. Think about yourself - did you pick any of the mutations that make your DNA slightly different from your parents? Did you pick any of the mutations that make your children's different from yours? Natural selection isn't random. It acts like a filter - eliminating the mutations that don't work as well, while allowing the ones that do to pass through. But it's only a filter. It relies on the raw material from random mutations.

It's also important to keep in mind that mutations aren't good or bad on their own. It all depends on the environment an organism is living in, the animals lifestyle, and other factors. DNA to make gills is very useful for a fish, but wouldn't do a damn for us.

So, let's go back to that ancestral population of apes. Somehow, it got split into at least two lineages. Those lineages, once they became reproductively isolated, could no longer share DNA between each other. So, whatever beneficial mutations popped up in one population would have been available only in that population. Any mutations that made the eventual chimp lineage better at climbing trees, for example, would have been unavailable to our lineage. Likewise, any mutations that made or lineage better at walking on the ground would not have been available to the lineage that led to chimps & bonobos. So, once that population was split, the two lineages went their own separate evolutionary ways.

Environment could also have played a role. Now, I doubt the following is exactly what happened, but it's an interesting thought experiment. What could have caused that ancestral population to become split? Imagine that it was a new river, that cut through their range. Imagine that the river became so big that the ancestral apes couldn't cross it. And suppose that on one side of the river, the forest stayed largely intact, while on the other side, the forest gave way to savannah. Now, with one lineage living in forest, and the other in savannah, you can see how natural selection would have favored different mutations in each of the two lineages, causing each to evolve markedly differently.

So, once you understand a bit about how evolution works, the question 'If man came from apes, why are the still apes?' seems nonsensical, and even a bit silly.

Here's a related blog entry I wrote a few years ago:
Why Do People Have a Problem With Our Relation to Other Apes?

That entry also addresses the semantics of this a bit. In my opinion, we are just a type of ape, so saying that we evolved from apes just seems obvious.


Selling Out