Category Archives: Astronomy

9. How to Think Like a Scientist – Astro Scale

Astronomy scale distances
Illustrators and designers have struggled with the best way to represent the Solar System graphically.

Imagine holding an automobile in your hand. It’s easy, just pick up a matchbox car. Matchbox cars have lots of features of a real car, just shrunk down. Scientists call this a “scale model.” Model because it is not a real car, and scale because all the parts are shrunk down by the same amount. A Matchbox car is scaled by about 1:64, meaning a real car is 64 times bigger than the toy.

thunderbird_matchboxA Barbie doll is also a scale model, but it can’t fit in the matchbox car because it is scaled differently. Barbie dolls are scaled by about 1:6. A real girl is about 6 times bigger than the doll. Barbie is over 10 times bigger than the matchbox car. For Barbie to drive a Matchbox car, the car would have to be about the size of a football, or she would have to be shrunk down to the size of penny.

Thinking like a scientist means trying to describe reality to make future predictions. A very effective way to do this is by using models. They help scientists understand things that are too humungously big (or small) or too freakazoidically far away to make sense of. But remember, for a model to make sense all objects in the model must be at the same scale. Barbies and Matchbox cars are both scale models, just not to the same scale.

Models are often mathematical, but can also be made of die-cast metal and plastic. The more accurate the model and the more closely it describes reality, the better. Some toy cars just roll. Others have working doors and make noise.

Definitely Not to Scale: Here is a real picture of a basketball and a real picture of a pea. Presented together, the pictures suggest something that anyone who has played basketball and eaten their vegetables knows to be untrue -- that they are roughly the same size. You'll notice that in scientific pictures, a ruler or some other object of known size is often included in the frame. Otherwise, it's very hard to know from a photograph how big something really is.
Definitely Not to Scale: Here is a real picture of a basketball and a real picture of a pea. Presented together, the pictures suggest something that anyone who has played basketball and eaten their vegetables knows to be untrue — that they are roughly the same size. You’ll notice that in scientific pictures, a ruler or some other object of known size is often included in the frame. Otherwise, it’s very hard to know from a photograph how big something really is. But of course, a ruler wouldn’t help much with objects of planetary size.

Consider our solar system: Our nearest star, the Sun, is big. Really big. 865,000 miles wide. 110 times wider than the Earth. But what does that mean? Let’s build a model.

Imagine the Sun was scaled down to the size of a basketball, how big would the Earth be? The size of a baseball? Of a golf ball? No. More like the size of a pea. A basketball and a pea.

To Scale, Sort of: In this picture, our basketball and our pea are presented in proper size relative to one another. Case closed? Not quite. Since this article is talking about models and has been discussing the earth and the sun in terms of peas and basketballs, this picture suggests that this is how the earth and sun would look together. It is, sort of, but for the model to work the pea would need to be much, much further away from the basketball, 94 times as far away, in fact. Many of the Solar System maps you see on posters show the planets and sun much closer together than they really are, even when the relative size differences are factored in.
To Scale, Sort of: In this picture, our basketball and our pea are presented in proper size relative to one another. Case closed? Not quite. Since this article is talking about models and has been discussing the earth and the sun in terms of peas and basketballs, this picture suggests that this is how the earth and sun would look together. It is, sort of, but for the model to work the pea would need to be much, much further away from the basketball, 94 times as far away, in fact. Many of the Solar System maps you see on posters show the planets and sun much closer together than they really are, even when the size differences are factored in.

The Sun is far away from us, 93 million miles away. But what does that mean? If the Sun was a basketball in the hoop of one basket at a basketball court, the Earth would be a pea at the other basket 94 feet away.

If we keep going, a quarter-mile away from the basketball Sun is a golf ball named Jupiter. A half-mile mile away is a pingpong ball called Saturn. Three-quarters of a miles away is a walnut named Neptune. The NASA spaceship Voyager 1 (the furthest out manmade object ever) is a speck of dust about a mile away from the basketball.

Perfect: We've created the most accurate picture yet! Only problem, it may be the world's most boring poster. (The yellow arrow helps you find the pea in this expansive field of blue. It's there - we promise). There is a reason they call it space.
Perfect: We’ve created the most accurate picture yet! Only problem, it may be the world’s most boring poster. (The yellow arrow helps you find the pea in this expansive field of blue. It’s there – we promise). There is a reason they call it space.
So the Sun is really big and far away But the other stars are so much farther away I can barely describe it. The Sun is just one of many stars in our Milky Way galaxy. One of the next closest stars is Alpha Centari over 26 trillion miles (4 light years away). But what does that mean? Let’s expand the model.

Suppose the Sun was a basketball was at Disneyworld, Orlando Florida, at the Space Mountain ride. At that scale, Alpha Centari would be another basketball at Space Mountain in Disneyland in Pasedena, California 2,500 miles away! And that’s just the closest star. Other stars in our galaxy are much farther away.

To make sense of them, we would have to change the scale of our model again. Shrink the Sun down to the size of a pea. Earth is the size of a poppy seed. Alpha Centauri is now a pea only a mile away still in Orlando Florida. Other stars in our Milky Way galaxy are peas in California. And that’s just our galaxy.

The next closest galaxy to the Milky Way is Andromeda. The Andromeda galaxy is 2 million light years away. What does that mean? We need another scale!

Stars are really far away. Musician George Hrab explained it best in his classic song, “Far.”

“I sense all the explosions going off inside your brain
As your mind gets blown by what I just did explain
Sorry if my words might drive you all insane
But that’s what happens when precision is your middle name

This stuff is far, [it’s really far] this stuff is far far far away
We’re talkin’ far, [like über far] you can’t get there by car in a day”


Talking Like a Scientist: Magnitude
Scientists have an easy tool to help make sense of really big numbers and make comparisons.. When looking at any two numbers, scientists count the number of digits in each number. For instance, with Barbie’s scale factor (the number of times it is shrunk), 64 has two digits a 6 and a 4. If two scale factors have the same number of digits (like 64 and 11), then scientists say they are of the same order of magnitude. If one scale has 2 digits and the other has 1 digits (like 64 and 6), the 64 is considered to be an order of magnitude smaller. Barbie dolls are an order of magnitude larger than a matchbox car.

Venus is closer to the Sun than Earth, but they are the same order of magnitude away. Andromeda is 6 orders of magnitude farther away from Earth than Alpha Centari.


References:

http://en.wikipedia.org/wiki/Matchbox_(brand)

http://www.eharm.net/night_sky_guide/distance_and_time/distance_and_time.html

Song, “Far” by George Hrab from the album Trebuchet.

Song “The Sun is a Mass of Incandescent Gas” – by They Might Be Giants, from the album Severe Tire Damage.

365DaysofAstronomy.org

Brave New Worlds and Goldilocks

In this photograph, taken by an astronaut on board the International Space Station, Venus is seen moving in front of, or transiting, the sun. Although the planet is small in comparison to the sun, it blocks part of the light reaching the earth. Using very sensitive instruments, scientists can now measure the very slight dimming that occurs when an exoplanet blocks part of the light from a distant star it orbits. (Photo: NASA)
In this photograph, taken by an astronaut on board the International Space Station, Venus is seen moving in front of, or transiting, the sun. Although the planet is small in comparison to the sun, it blocks part of the light reaching the earth. Using very sensitive instruments, scientists can now measure the very slight dimming that occurs when an exoplanet blocks part of the light from a distant star it orbits. (Photo: NASA)
Do we know if there are planets orbiting other stars? Until about 20 years ago, the answer would have been “NO!” Most astronomers believed that there were probably planets going around other stars, but that it was not possible to find them. Planets are just so small compared to stars and the stars are so far away.

Then, in the 1990s, some really smart scientists thought up some crazy ideas to detect planets orbiting distant stars.

The simplest one became known as the Transit Method. When Mercury or Venus travel across the disc of the Sun (known as transiting the Sun), the amount of sunlight hitting the Earth goes down.

Think about a light bulb burning and a fly buzzing around it. While you look at the bulb as the fly buzzes by, the amount of light you see from the bulb is slightly less than when the fly is gone. It’s a very small amount, but the bulb does in fact become dimmer.

Now what if we could measure the brightness of a distant star incredibly accurately, and see if it dims? And what the star dims and brightens on a regular basis (like once a year)?

If that’s the case, it might be caused by a planet orbiting the star.

Let me pause and be the science grammar policeman. Technically, as poor Pluto learned, there are only 8 planets; a planet is now defined as a celestial body that, among other things, orbits our Sun. So if we’re talking about worlds orbiting some other star, they cannot be called planets. Astronomers call them exoplanets. “Exo” means “outside,” so exoplanet means a planet orbiting a star outside our solar system.

Using the Transit Method and other ingenious methods, astronomers started finding exoplanets, lots of them. It takes a long time to be sure. It takes multiple observations by multiple teams using multiple methods before an exoplanet is confirmed.

Now, hundreds of exoplanets have been confirmed. Thousands more listed as probable but haven’t been confirmed yet. The number keeps growing.

The artist's concept depicts NASA's Kepler mission's smallest habitable zone planet. Seen in the foreground is Kepler-62f, a super-Earth-size planet in the habitable zone of a star smaller and cooler than the sun, located about 1,200 light-years from Earth in the constellation Lyra. Kepler-62f orbits it's host star every 267 days and is roughly 40 percent larger than Earth in size. The size of Kepler-62f is known, but its mass and composition are not. However, based on previous exoplanet discoveries of similar size that are rocky, scientists are able to determine its mass by association. Much like our solar system, Kepler-62 is home to two habitable zone worlds. The small shining object seen to the right of Kepler-62f is Kepler-62e. Orbiting on the inner edge of the habitable zone, Kepler-62e is roughly 60 percent larger than Earth. (Image credit: NASA Ames/JPL-Caltech/Tim Pyle)
The artist’s concept depicts NASA’s Kepler mission’s smallest habitable zone planet. Seen in the foreground is Kepler-62f, a super-Earth-size planet in the habitable zone of a star smaller and cooler than the sun, located about 1,200 light-years from Earth in the constellation Lyra. Kepler-62f orbits it’s host star every 267 days and is roughly 40 percent larger than Earth in size. The size of Kepler-62f is known, but its mass and composition are not. However, based on previous exoplanet discoveries of similar size that are rocky, scientists are able to determine its mass by association. Much like our solar system, Kepler-62 is home to two habitable zone worlds. The small shining object seen to the right of Kepler-62f is Kepler-62e. Orbiting on the inner edge of the habitable zone, Kepler-62e is roughly 60 percent larger than Earth. (Image credit: NASA Ames/JPL-Caltech/Tim Pyle)
In 2009, NASA launched the Kepler Space telescope to find stars with exoplanets. It tracked the brightness of over 100,000 stars for over 4 years. It has discovered at least 900 confirmed exoplanets, and has provided scientists with so much data that will take years to completely review.

The Kepler scientist have found lots of weird planets. Huge planets bigger than Jupiter yet closer to their star than Mercury, orbiting every few days! They found planets twice the size of Earth, dubbed “Super Earths” really far away from their stars. They found planets orbiting two stars!

Scientists have even been able to determine all sorts of characteristics about these exoplanets including:

  • How big they are.
  • How long is their year.
  • How far away from their star is their orbit.
  • What chemicals are in their atmosphere

Naturally, astronomers want to locate planets that have the right conditions for life. They are looking for exoplanets that have orbits that means they are not too hot and not too cold, planets that are “just right” for life. They call this the Goldilocks zone. They have many candidates, so who knows what they’ll learn in the future?

The Gemini Planet Imager’s first light image of Beta Pictoris b (Processing by Christian Marois, NRC Canada)
The Gemini Planet Imager’s first light image of Beta Pictoris b (Processing by Christian Marois, NRC Canada)
In just a few years exoplanets have gone from science fiction to science fact. Earlier this year, scientists in Chile used special techniques and even took a photograph of an exoplanet! See below the image of Beta Pictoris b, a planet orbiting the star Beta Pictoris. In the picture below, the light of the star itself is blocked out by a disk so the planet can be seen. It’s great to see science in action.

Keep up with the latest exoplanet discoveries yourself at http://kepler.nasa.gov/Mission/discoveries/

Spotting the International Space Station

Astronaut Chris Cassidy works outside the space station on May 11, 2013.  Credit: NASA
Astronaut Chris Cassidy works outside the space station on May 11, 2013. Credit: NASA
Almost everyone has heard of the International Space Station (ISS). It is one of the most spectacular technological achievements ever, but it is easy to take it for granted. After all, it has been in orbit for more than 13 years. Astronauts have lived on board all that time, conducting science experiments and learning the kinds of things that will help humans extend their reach into space. Since ISS may be the coolest laboratory ever built, we recommend making a New Year’s commitment to keeping track of what’s going on there.

Luckily, NASA makes it easy to keep up with ISS. On the web site http://spacestationlive.nasa.gov/ you will find animations and education resources about “humankind’s permanent outpost in space.” You can find details of the daily activities for each astronaut, along with timelines and live video feeds. You can view the same data being viewed by ground control officers at NASA, so if you’ve ever wanted to try your hand at being a flight director, start here.

For an overview of what is going on with ISS, NASA provides a great option. The YouTube channel ReelNASA provides a weekly newscast about what’s happening aboard the International Space Station. You’ll find links to in-depth information about the experiments and projects that are discussed. You can even send in your own questions. It is pretty cool.

The space station, including its large solar arrays, spans the area of a U.S. football field, including the end zones, and weighs 924,739 pounds. The complex now has more livable room than a conventional six-bedroom house, and has two bathrooms, a gymnasium and a 360-degree bay window.
The space station, including its large solar arrays, spans the area of a U.S. football field, including the end zones, and weighs 924,739 pounds. The complex now has more livable room than a conventional six-bedroom house, and has two bathrooms, a gymnasium and a 360-degree bay window.
Spotting the International Space Station
For the ultimate in “keeping up with the ISS,” nothing beats taking a look with your own eyes. The ISS is the size of a football field and orbits Earth at an average altitude of 220 miles. Just before sunrise or when night has fallen where you live, the ISS is sometimes overhead and high enough to still be in the sunlight. It is highly reflective and very bright, so it is easy to spot if you know when to look. It moves quickly across the sky, which isn’t a surprise considering that the ISS orbits the Earth every 90 minutes and travels at a speed of 17,500 miles per hour. Between moving fast and being wildly bright, it is easy to spot.

To know when to look, go the the NASA site http://spotthestation.nasa.gov/ and click on Location Lookup. Simply enter your location information (Country, State, City, etc.). The site will display information about when the ISS will be visible to you. The main thing, of course, is to find a day and time when you can go outside and look, and then to hope it is not too cloudy during your viewing window.

The results for your local area provide all the information you need to pick a good viewing time. Then you just have to hope it is not cloudy.
The results for your local area provide all the information you need to pick a good viewing time. Then you just have to hope it is not cloudy.
The next important thing is to make sure the ISS will be high enough for you to see. For the “Max Height” column, know that 90 degrees equals directly overhead, so any number above, say, 45 degrees will put the ISS high in the sky. Lower numbers mean the ISS will appear closer to the horizon, so trees or buildings might be in the way and block your line of sight.

Use this graphic to visualize what path the ISS might take in the sky. Credit: NASA.
Use this graphic to visualize what path the ISS might take in the sky. Credit: NASA.
And remember, sight lines work both ways. Since NASA streams live views of the Earth from the ISS, you can very easily go outside to wait for the ISS to appear overhead while watching the live view of Earth from the ISS on a smartphone or tablet computer (if you have a web connection). This allows you to see what astronauts aboard the ISS see if they look down. If it is just past sunset where you live, for instance, look for the line on Earth between night and day to figure out about where you are in terms of east and west.

When the ISS blazes its way across the sky hundreds of miles overhead, you will have achieved a dual, realtime perspective that would have been almost impossible to dream of just a few decades ago. Give it a try!

This picture shows a five-second exposure of the ISS passing just above the Pleiades star cluster on Dec. 27, 2013. The length of the path over five seconds gives you an idea of how fast the ISS moves across the sky.
This picture shows a five-second exposure of the ISS passing just above the Pleiades star cluster on Dec. 27, 2013. The length of the path over five seconds gives you an idea of how fast the ISS moves across the sky. Credit: Clifton Dowell

Houston, We Have a Photo Album! Photographs from Apollo Astronauts

moonmanOne of my favorite books about space has very few words in it at all. “Full Moon” celebrates the photographs of the Apollo moon missions taken by the astronauts themselves. Their spacesuits had film cameras mounted on the front at chest level. As they moved around the surface of the moon, they carefully documented everything they could, mostly for scientific purposes.

That means that today, a lunar geologist studying a rock brought back from the moon can see exactly how the rock was situated on the surface there before it was picked up — extremely valuable information!

Of course, in addition to having scientific value, the pictures are also just incredibly cool and interesting to look at. “Full Moon” has about 130 pictures, organized by mission stage (the trip there, lunar orbit, the surface, splashdown). The photographer who put the book together, Michael Light, had plenty of material to work with — there are about 32,000 pictures from the Apollo missions. He used his artistic vision to choose photographs that are beautiful as well as informative.

full-moon-barA Fresh Look
While dozens of pictures from the U.S.A.’s famous race to the moon are as familiar as the nose on your face, thousands and thousands of pictures have hardly been seen by anyone. But even when it comes to pictures you’ve seen before, you’ve never seen them quite like this.

The 17 Apollo missions took place between 1967 and 1972, so of course the photographs were taken with film cameras. NASA had to keep such important film safe, so here’s what happened:

When astronauts got back and their film was developed, a number of the pictures were chosen as being the most news-worthy from that particular mission. The film negatives for those pictures were copied. Those copies were used to make pictures for newspapers, magazines, which then made their own copies. Publishers often ended up using copies of copies of the originals.

This process had two results. First, it caused the same pictures to be used over and over again. Second, it meant that publishers were often stuck using poor quality negatives.

By the 1990s, when Michael Light negotiated with NASA for access to the archive of original film negatives, technology had come a long way. Instead of taking photographs of the negatives he picked for the book, he scanned them using a high-resolution digital film scanner. This allowed the photographs in “Full Moon” to be reproduced with a sharpness and clarity that is stunning. All you can say, is “Wow.”

Nowadays, you can explore the Apollo archives yourself by going to one of the web sites that have databases of all the pictures (we provide some links below). You’ll see some interesting sights and gain a real appreciation for the amount of work the astronauts did simply to train for their trips to the moon. But for a gripping, one-stop ride from launchpad to splashdown, give “Full Moon” a look. You won’t be disappointed in this perfect artistic interpretation of one of the greatest technological achievements of all time.

Fun Phineas Fact
Getting to the moon took a lot of time and a lot of work. The archives of the Apollo missions show spectacular views of barren lunar surface and of the beautiful blue sphere of Earth hanging in an ink-black sky. But a look through more of the galleries below will give you insight into how much more there was to getting to the moon and back than simply starting a countdown.Selected images from NASA

The Project Apollo Gallery

Slideshow of the Image Scans Used in Full Moon