posted Dec 22, 2011 8:06 PM by Webmaster Science Bus
Polar bears mainly live in the Arctic Circle. The Arctic Circle is a area a certain distance from the Equator, which includes parts of Alaska, Canada, Russia, and other countries.  Since the Arctic is composed of mostly ice, polar bears can live on ice that is hundreds of miles from the nearest shore. In spite of this, most polar bears are actually born on land! Also, when the sea ice starts to melt, such as during the summer, the bears begin to retreat closer to land. Fun facts about polar bears! - Polar bears can swim up to 100 miles at a time, and at an average of 6 miles per hour.
- Polar bears tend to overheat more than be cold
- Polar bears do not hibernate. However, all polar bears may create a den from the snow for a short time to avoid bad weather.
Thanks to:
http://endangeredpolarbear.com/fun_facts_about_polar_bears.htm http://kids.nationalgeographic.com/kids/animals/creaturefeature/polar-bear/ http://en.wikipedia.org/wiki/Polar_bear
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posted May 3, 2010 4:14 PM by Dmitri Skjorshammer
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updated May 11, 2010 6:59 AM by Neal Pisenti
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Interesting question! The answer is yes. There is one definite ending for Earth: stellar evolution of the Sun.
Let's start by explaining what makes the sun The Sun. Let me remind you that the Sun's "fuel" is hydrogen. The sun's own gravity is pulling all of the hydrogen gas together, but at the same time, fusion of hydrogen "fuel" is pushing everything outwards. These forces are carefully balanced between collapse from its own gravitational weight and explosion from the energy produced in fusion. The result is a net force of 0. That is: the Sun isn't growing and it's not squeezing itself together, it remains in equilibrium.
Like every other type of "fuel", there is only a limited supply of it. So some day, Sun's hydrogen supply will run out. So what's going to happen? Well once the hydrogen in the *core* of the Sun runs out, the gravity within the core will exert a BIGGER force so the Sun will contract. This will heat up the surface of the core and initiate further fusion reactions. As a result, the energy output will be so great that it will increase the brightness of the Sun by 1000 times! This spells trouble. While we're not that close to the Sun, an increase in the brightness will be strong enough to kill all life! Imagine the temperature associated with this brightness (for example: have you ever held your hand near a lightbulb?). Don't worry, though, this won't happen for at least another 5 billion years (that's 5,000,000,000 years from now!!!).
Some scientists suggest that there are other threats to humanity. If you've heard the words global warming and climate change, you probably know what we mean. These theories state humans are having an observable effect on our environment. The amount of carbon dioxide we're releasing into the air is changing the makeup of the atmosphere: the more carbon dioxide there is, the more sunlight is trapped inside our atmosphere (see Figure 2):
As a result, the average temperature around the Planet increases. While humans may not notice these small changes, it can have a severe effect on sea level and animal habitats. So we have to worry more about our own actions than the evolution of the sun! |
posted Jan 21, 2010 10:54 AM by Neal Pisenti
The simple answer: No, witches are not real. They are fun to imagine, which is why witches appear in a lot of fiction stories and hollywood movies, but in reality there is no such thing as magic. The history behind people's belief in witches, however, is both sad and interesting. Back in the medieval times, people were very afraid of witches and witchcraft because of it's association with the devil. If someone was suspected of being a witch, they were often burned at the stake without receiving a fair trial. Perhaps the most famous example is the Salem witch trials. These started in 1692 in Salem, Massachusetts (which was then a British colony) when the daughters of the local Reverend started to act really bizarrely. They screamed, threw things around the room, contorted themselves, and complained of pinpricks. They accused three women in the town of doing this to them by witchcraft, but the accusations had no scientific foundation. The accused women were outcasts from the society: one was homeless, one didn't attend church regularly, and one was a slave. They were arrested, and based on the testimony of the two girls, they were hanged for witchcraft. However, they obviously were not actually witches, and the fact that they were hanged reflects an unfounded fear of witchcraft that was very common in that day.
The net of the story is that we should carefully examine the evidence before reaching any conclusion. There is no evidence of witchcraft, but people used to still believe in it because that is what everyone else believed. The Salem witch trials were an example of people acting contrary to the best scientific evidence, and people died as a result! Especially in cases where someone's life or natural rights are concerned, we cannot be swayed by unscientific modes of thinking. |
posted Dec 20, 2009 5:25 PM by Science Bus 5C
No. This is a great question to ask, especially since it has been popularized by the new movie 2012. Why do people believe in 2012? The idea originated from the Mayans. According to the Mayans, their calendar ends in 2012, causing a destruction of the old world and a creation of the new world. The Mayans believed it but didn't have any evidence. That is why scientists are skeptical of this hypothesis. Let's see what the movie has to say about this. Don't read this until you've seen the movie though!
Do you remember what happened in the movie? First, a scientist in India discovers that particles called neutrinos from a massive solar flare (explosion on the surface of the sun) are hitting the earth. These neutrinos supposedly act as microwave radiation, much like your microwave. What do they do? They start heating Earth's core. As a result of heating, Earth's north and south pole undergo a change in location. (Remember in the scene where a scientist said that the north Pole is now in Wisconsin?) The movie showed this as causing huge earthquakes, enormous volcanoes, and killer tsunamis. As a result, billions of people died because they were unprepared for this.
Before we go further, it is worth talking about the "science" in the movie 2012. As with many movies, there is a kernel of truth but the majority of what happens is not scientifically accurate. For example, there are particles called neutrinos, but they hardly interact with matter at all and the vast majority of them pass right through the earth without being noticed. They do not act like microwaves, and would not cause the core to heat up. Microwaves are a form of electromagnetic radiation ( ie, light) with a particular wavelength. They cause water to heat up because of particular properties water has (the microwaves cause water molecules to rotate back and forth, which increases what is called the kinetic energy of the water, which in turn causes the water to heat up), but would not cause the core of the earth to heat up as portrayed in the movie. As for the earth's magnetic field, it does change direction every ten thousand to one million years in a process called geomagnetic reversal. This process is not fully understood, but is thought to involve the circulation of liquid metal in the earth's core.
Now, to answer your question: there is no evidence that the world will end in 2012. The movie is meant to be entertainment, and while fun to watch it is not based on real science. While neutrinos do exist and the earth's poles do change orientation, this has not happened in roughly 780,000 years and there is no reason to believe it will happen in 2012.
So don't worry about it! Keep on thinking and asking questions. It never hurts anybody!
Solar flare (Copyright Mila from Wikipedia)
Axis of Rotation (The tilted line is the North/South pole line. Note that this shows that the North and South Pole aren't exactly "straight up or down"). This is thanks to Daniel Nillson under Creative Commons from Wikipedia. |
posted Nov 8, 2009 12:38 PM by Science Bus 5C
You've hit right on the spot with this question. The thing is, no one knows for sure where words come from. There are three explanations that scientists are divided over.
Remember evolution lesson? Some scientists think that cavemen who could talk better, had a better chance of surviving. Now imagine you're a caveman some 200,000 years ago and you see a huuuge tiger who wants to eat your family. If you tell your family (by yelling or screaming), you can save your family. If you're not good at yelling or screaming, your whole family will probably be eaten. Do you see where evolution comes in? Those who can communicate better pass on their genes to their children.
Another answer, scientists say, is that it's a result of human skills, such as planning and memory. Scientists who believe this say that language happened as a result of humans planning, thinking and memorizing. Think about the wheel: Who invented the first wheel? Someone probably happened to stumble upon the idea of a round wheel. The same with language. At some point, people started to memorize certain yells or screams. Over many thousand of years, words developed.
Another answer is that the brain allows humans to create language. These scientists say that there is some piece of brain that allows humans to easily create and understand language. Scientists who believe this say that this "talent" is with you at birth.
The important thing to take away from all this is that there are many answers. The above answers should give you an idea of what scientists believe. Now, what do you think? Do you believe the scientists? Do you have a better explanation? Give it a shot! |
posted Nov 8, 2009 11:49 AM by Science Bus 5C
Great question! The answer is yes. In fact, as of today, there are 404 known planets beyond our Solar System! Like Earth, these planets spin around a huge star. In our Solar system, this star is called the Sun.
Out of the 404 planets, many are gas giants. This means they have no surface that you can land on (think Jupiter). Some of these planets are really close to their they're orbiting and others are far away. What's so amazing is that some planets are just the right distance from their star that their temperature and atmosphere allows for the possibility of life. Can you imagine meeting an alien from another planet? It's not as crazy as you think!
Recently, scientists have found a planet called Gliese 581d. This planet is just the right distance away from its Star. Scientists think that these conditions allow it to have liquid water (which is necessary for life). This star is 8 times the mass of Earth and it is 117,000,000,000,000 miles away from us! It's a long-long ways away!
Key Terms Solar System: a system of stars and planets in which we live. It consists of one star, the Sun, and the following planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. Note that Pluto is no longer called a planet.
Pluto: Believe it or not, Pluto is no longer called a planet. How can a planet no longer be a planet? Well, Pluto didn't change; it's our understanding of planets that did. Scientists now say that a planet is a body that 1) orbits, or "spins", around the Sun, 2) is round and 3) is not influenced by other bodies (such as meteors) in its orbit around the Sun. Pluto fails 3) because there are heavier objects in its orbit. |
posted Nov 1, 2009 2:35 PM by Science Bus 5C
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updated Nov 9, 2009 1:53 AM
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When you break it down, a movie is really just a sequence of still pictures that move by so fast that your brain can't tell them apart! Each picture is called a frame, and is slightly different from the previous frame. When you project these frames quickly one after another onto a screen, your brain blends them together to form a moving image. Most movies play about 30 frames every second!
Modern day movies are filmed digitally, but in the old days movies were kept on reels of film. Each square in the film was a frame in the movie, and a projector would wind the film past a bright light to project the image onto the screen. Have you seen a reel of film before? If not, check out the picture below!
You can actually make your own movies right at home. Take a pad of sticky notes, and down in one corner draw some stick figures (or something else!). Flip to the next sticky note, and draw the same scene but changed slightly (as if the stick figures had moved a little bit). Repeat this for the whole pad of sticky notes, and then try flipping through them with your thumb. Does it look like your pictures are moving? This is called a flipbook. This is the same principle that makes the images in a movie look like they are moving!
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Reel of film | |
Film movie projector |
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posted Nov 1, 2009 2:34 PM by Science Bus 5C
Several of you asked some similar questions, and this response will address them all! Here they are:
- Where did people come from?
- How did people evolve?
- How did animals evolve?
- Why were there dinosaurs before people?
- What was the first animal in the world (except for the dinosaur)?
Scientists think that all of the life on earth (everything from your baby sister to giraffes to the microbes at the bottom of the ocean!) evolved from a single organism. Although we do not know exactly how life first started, once it appeared natural selection took over and drove the evolution of millions of different species. Scientists think that the first life appeared roughly 4 billion years ago, and for most of earth's history, the only living things were single celled organisms! About 475 million years ago, the first fish evolved, followed by land plants and animals and eventually dinosaurs. Around 65 million years ago, a very large asteroid hit the earth causing many of the dinosaurs to go extinct. But did you know some dinosaurs are still alive today? Crocodiles are one example! They are thought to be roughly 200 million years old, whereas the dinosaurs only went extinct 65 million years ago.
The reason we see such biodiversity on earth (do you remember what biodiversity means?) is because of something called natural selection. Organisms that are better able to survive in their habitats are more likely to pass their traits on to their children. You know how you might look similar to your parents and to your siblings? This is because you share much of the same DNA as the rest of your family. This DNA encodes all of your traits, and might make you a faster runner than your neighbor. If you were living 100 million years ago, being able to run faster might make you more able to survive. So your children, who would also be able to run fast, would be more likely to pass on that gene than your neighbor who is too slow to outrun the lion.
So to answer your questions: We don't know what the first animal was, or even what might have looked like. But we do know that all other animals (including you!) evolved from that first animal over the course of millions of years. And how do humans fit in? If all of earth's history were condensed down to an hour, humans would have only been around for the last tenth of the last second. The other 59 minutes and 59 seconds would have seen billions of years of evolutionary history that we are just beginning to explore!Sources: http://www.uky.edu/KGS/education/clockstime.htm http://en.wikipedia.org/wiki/Crocodile http://en.wikipedia.org/wiki/Timeline_of_evolution |
posted Nov 1, 2009 2:26 PM by Neal Pisenti
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updated Nov 1, 2009 6:02 PM
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Believe it or not, but this is still an area of very active scientific research! It is an excellent question, and although scientists have made a lot of progress, we still do not know the complete answer.
Back in the early 1900s, a man named Georges Lemaître proposed what is now the Big Bang theory. All of the current astronomical evidence suggests that our universe was formed by an event called the Big Bang. About 13.7 billion years ago, the universe started as a singularity of infinite density and temperature (remember what density means? Look at the bottom of the page for the answer!). This singularity suddenly exploded outwards (in a big bang!), and underwent a period of very rapid growth called inflation. A few minutes after the big bang, the universe had a temperature of about 1.8 billion degrees Fahrenheit (almost 200,000 times the temperature of the sun). At this point, protons and neutrons began to form, but it wasn't for another 379,000 years until these protons combined with electrons to form the first hydrogen atoms. Slowly, these hydrogen atoms came together under gravitational attraction to form stars and galaxies, and the universe began to look a lot like it does today.
What are some of the reasons scientists think this theory is correct? One of the big pieces of evidence is what is called the cosmic microwave background radiation. It turns out that no matter where we point our telescopes in the sky, space has a fairly constant temperature of about 3 Kelvin (or about 454 degrees below zero, which is very cold!). But because it is constant no matter where we look, this suggests that at one time all points in space were very close to each other in thermal equilibrium.
What are some of the unanswered questions? It turns out that everything in space is moving away from each other at increasing speeds. Why might this be a problem for our understanding of the universe? The gravitational force is attractive, meaning things should want to move closer to each other, not further away. This has lead scientists to postulate the existence of dark energy, which is some unknown substance that permeates all of space causing this repulsive force. Whoever discovers what dark energy really is will definitely win the Nobel prize!
On the other hand, scientists have also postulated the existence of some sort of dark matter. This is slightly less mysterious, but astronomers have observed galaxies that shouldn't be able to stay together based on the amount of matter we can observe. In other words, the amount of matter we can see (from stars, etc.) would not produce a large enough gravitational field to keep the stars on the edge of the galaxy from flying away. Possible explanations for this include super massive black holes near the center of the galaxies, or large amounts of dust and other matter that doesn't emit light.
It will be interesting to see what discoveries are made in the future to explain some of these mysteries. Perhaps you will be the one to discover dark energy!
Key Terms
- Density: this is just the mass divided by the volume. High density objects have a lot of mass in a small volume. The singularity at the big bang is thought to have infinite density!
- The Big Bang: This is the cosmological theory that says the universe started as a singularity of infinite density, and exploded outwards to create what we know as the universe.
- Inflation: This is the period in cosmological history where the universe underwent extremely rapid expansion.
- Kelvin: This is the way scientists measure temperature. If you've ever heard of absolute zero, this corresponds to 0 K (or zero Kelvin). You should do some research and figure out how to convert from Fahrenheit to Kelvin and impress your friends!
- Cosmic Microwave Background Radiation: This is the cause of the universe's "empty space" temperature of 3 Kelvin, and one of the reasons scientists think the big bang theory is correct.
- Dark Matter: This is some sort of matter we can't see (it doesn't emit light like the sun), but makes up the majority of mass in the universe.
- Dark Energy: This is some unknown substance that causes a repulsive force, and is why we see galaxies moving away from each other at faster and faster speeds!
Sources: http://en.wikipedia.org/wiki/Big_Bang |
posted Oct 26, 2009 5:00 PM by Neal Pisenti
Good question! Scientists are still not certain about how the moon formed, but here is the most recent and widely accepted theory:
About 4.5 billion years ago, around the time when the solar system was forming, the earth was hit by a smaller planet that had formed nearby. This caused a lot of debris to detach from the earth and fly into orbit. The individual pieces of debris were attracted to each other by the gravitational force, and slowly collected together to form what we now see as the moon.
Why do scientists think this? It's important to realize that not just any idea is elevated to the status of a scientific theory. As a scientist, you must provide evidence for your theory to convince other people to think it is correct. Some of the evidence for this theory includes the fact that there is almost no iron in the moon, which means it could not have been formed at the same time as the earth which has an iron core. Additionally, one would expect other planets to have similar moons if it was a natural part of the solar system's formation. However, Earth is the only planet with a moon that is so large in proportion to its own size. There are other reasons to think this theory is correct, but those are two of the main ones.
Vocabulary:
- Gravitational Force
- You're probably familiar with this concept already! We've always known about gravity, but it wasn't until the 1700's that Sir Isaac Newton formalized what is known as a gravitational force. Essentially, any two objects with mass experience an attractive force which tries to pull them together. That's why all of the debris scattered from the earth pulled together to form the moon!
- Scientific Theory
- A scientific theory is a statement or set of statements that describe the world. Scientists use the word 'theory' differently from the way we usually use it in conversation. A scientific theory must have a lot of supporting evidence before we would accept it. It also must explain things (rather than just state the way they are!) and hopefully predict new phenomenon which can be tested!
References: http://www.psi.edu/projects/moon/moon.html |
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