Fraser Cain, Author at Universe Today

September 23, 2009December 24, 2015 by Fraser Cain

Pictures of Rivers

Here are some cool pictures of rivers taken by various spacecraft.

Here’s a picture of the Mississippi river delta. The image was captured by Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) aboard NASA’s Terra satellite.

This is an image of flooding on the Betsiboka River in Madagascar. The flooding was created by Tropical Storm Eric, which swept through the region in early 2009. This photograph was taken by astronauts on board the International Space Station.

People rely on the Colorado River so much that very little of it actually reaches the ocean. Instead, almost all of the water that flows through the river is used for irrigation along its route.

This is a picture of the river delta for the Ganges. In fact, the Ganges combined with the Brahmaputra River make up the largest river delta in the world. The rivers flood from snow melt in the nearby Himalayas.

This is a picture of the Niger River. It was captured by the ASTER instrument on board NASA’s Terra Earth Observation satellite.

We have written many articles with pictures of rivers for Universe Today. Here’s an article about flooding in the Red River, and here’s an image of the Yangtze River from space.

We have also recorded an episode of Astronomy Cast all about the Earth. Listen to it here, Episode 51: Earth.

September 23, 2009December 24, 2015 by Fraser Cain

Solar System Coloring Pages

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Want to find some cool Solar System coloring pages? Here are some links to resources we’ve been able to dig up from around the Internet.

Check out the offerings from Coloring Castle. I find it cool that they offer a version with Pluto, and then another without Pluto.

And one of the best resources on the internet for this kind of thing is Enchanted Learning. They’ve got a page just for Solar System coloring pages.

Windows on the Universe has coloring pages for all the planets in the Solar System. They even have an entire PDF book that you can print off with all the planets (including Pluto).

Coloring Fun has some more solar system pages for coloring.

And here are some resources from About.com.

Here are some resources from NASA. And here’s a link to a 3d Solar System.

We have written many articles about the Solar System for Universe Today. Here’s an article about Solar System projects for kids, and here’s an article about how to build a model of the Solar System.

We have also recorded an audio tour through the Solar System for Astronomy Cast. Start here at Episode 49: Mercury.

September 22, 2009December 24, 2015 by Fraser Cain

Earth’s Circumference

The Earth’s circumference – the distance around the equator – is 40,075 kilometers around. That’s sounded nice and simple, but the question is actually more complicated than that. The circumference changes depending on where you measure it. The Earth’s meridional circumference is 40,008 km, and its average circumference is 40,041 km.

Why are there different numbers for the Earth’s circumference? It happens because the Earth is spinning. Think about what happens when you spin around holding a ball on a string. Your rotation creates a force that holds the ball out on the end of the string. And if the string broke, the ball would fly away. Even though the Earth is a solid ball of rock and metal, its rotation causes it to flatten out slightly, bulging at the equator.

That bulge isn’t very much, but when you subtract the meridional circumference (the equator when you pass through both poles), and the equatorial circumference, you see that it’s a difference of 67 km. In other words, if you drove your car around the equator of the Earth, you would drive an extra 67 km than you would if you drove from pole to pole to pole.

And that’s why the average circumference of Earth is 40,041 km. Which answer is correct? It depends on how accurate you want to be with your calculation.

We have written many articles about the Earth for Universe Today. Here’s an article about how fast the Earth rotates, and here’s an article about how round the Earth is.

Want more resources on the Earth? Here’s a link to NASA’s Human Spaceflight page, and here’s NASA’s Visible Earth.

We have also recorded an episode of Astronomy Cast about Earth, as part of our tour through the Solar System – Episode 51: Earth.

September 18, 2009December 24, 2015 by Fraser Cain

Space Wallpapers

Here are some amazing space wallpapers. If you want to make one of these your computer desktop wallpaper, just click on the image. That will take you to a much larger version of the image. You can then right-click on the image and choose, “Set as Desktop Background”. That will make any of these space wallpapers your desktop background.

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This is one of the most famous space photographs every taken. It’s called “Earthrise”, and it was captured by the crew of Apollo 8 as they were orbiting around the Moon. They saw the Earth rising over the Moon’s horizon and captured this amazing photograph.

NASA created this amazing wallpaper as part of its celebration for Sun-Earth day in 2008. You can see the Sun shining just outside of the photograph above.

Almost 1000 years ago, a star detonated in the sky as a supernova, shining brilliantly for a few days. After it faded away, it was replaced by this amazing nebula.

This amazing space wallpaper shows active star formation in the Eagle Nebula. These newly forming stars are blasting out huge clouds of gas and dust into space.

Here’s a beautiful image of Saturn captured by NASA’s Cassini spacecraft during a time that it was positioned over the planet’s pole.

We have got lots of image galleries here in Universe Today. Here are some Earth wallpapers, and here are some Venus wallpapers.

You can also download some cool space wallpapers from NASA’s JPL, and here are some wallpapers from Hubble.

You might also want to try listening to an episode of Astronomy Cast. Here’s an episode just about the Hubble Space Telescope.

September 17, 2009December 24, 2015 by Fraser Cain

God Particle

The Large Hadron Collider at CERN. Credit: CERN/LHC

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When the media talks about the “god particle”, they’re really talking about a theoretical particle in physics known as the higgs boson. If reality matches the predictions made by theoretical physics, the higgs boson is the particle that gives objects mass. It explains why objects at rest tend to stay at rest and objects in motion tend to stay in motion.

One of the primary goals of the Large Hadron Collider in Switzerland is to search for the so called “god particle”. When it finally gets running, the Large Hadron Collider, or LHC, will run beams of protons around a 27 kilometer circle, slamming them together at close to the speed of light. All the kinetic energy of the protons is instantly frozen out as mass in a shower of particles. Remember Einstein’s famous E=mc² formula? Well, you can reconfigure the equation to be m = E/c².

The higgs boson is thought to be a very heavy particle, and so it takes a lot of energy in the collider to create particles this massive. When the LHC starts running, it will collide protons at higher and higher energies, searching for the higgs boson. If it is found, it will confirm a theorized class of particles predicted by the theory of supersymmetry. And even if the higgs boson isn’t found, it will help disprove the theory. Either way, physicists win.

The term “god particle” was coined by physicist Leon Lederman, the 1988 Nobel prize winner in physics and the director of Fermilab. He even wrote a book called the “God Particle”, where he defended the use of the term.

We have written many articles about the Higgs Boson and the Large Hadron Collider here on Universe Today. Here’s an article about how the LHC won’t create a black hole and destroy the Earth. And here’s more on Fermilab’s search for the Higgs Boson.

We have also recorded an episode of Astronomy Cast all about the higgs boson. Listen to it here, Episode 69: The Large Hadron Collider and the Search for the Higgs Boson.

September 16, 2009May 4, 2017 by Fraser Cain

Composite Volcano

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Geologists have identified 3 major types of volcanoes. There’s the shield volcano, formed from low viscosity lava that can flow long distances. There are cinder cone volcanoes, which are made by the eruption of lava, ash and rocks that build up around a volcanic vent. But the last type is the composite volcano, and these are some of the most famous volcanoes (and most dangerous) in the world.

A composite volcano is formed over hundreds of thousands of years through multiple eruptions. The eruptions build up the composite volcano, layer upon layer until it towers thousands of meters tall. Some layers might be formed from lava, while others might be ash, rock and pyroclastic flows. A composite volcano can also build up large quantities of thick magma, which blocks up inside the volcano, and causes it to detonate in a volcanic explosion.

Composite volcanoes are fed by a conduit system which taps into a reservoir of magma deep within the Earth. This magma can erupt out of several vents across the composite volcano’s flanks, or from a large central crater at the summit of the volcano.

Some of the most famous volcanoes in the world are composite volcanoes. And some of the most devastating eruptions in history came from them. For example, Mount St. Helens, Mount Pinatubo, and Krakatoa are just examples of composite volcanoes that have erupted. Famous landmarks like Mount Fuji in Japan, Mount Ranier in Washington State, and Mount Kilimanjaro in Africa are composite volcanoes that just haven’t erupted recently.

When large composite volcanoes explode, they can leave behind a collapsed region called a caldera. These are deep, steep-walled depressions which marked the location of the volcano. And it’s in this region that a new composite volcano will build back up again.

Another name for composite volcanoes are stratovolcanoes.

We have written many articles about composite volcanoes for Universe Today. Here’s an article about the recent eruption of Mount Redoubt in Alaska, and here’s an article about Mount Etna.

You can learn more about composite volcanoes from the USGS.

And we have recorded an entire episode of Astronomy Cast just about volcanoes. Listen to it here, Episode 141: Volcanoes, Hot and Cold.

September 16, 2009December 24, 2015 by Fraser Cain

Who Discovered Jupiter?

Jupiter from the newly refurbished Hubble. Credit: NASA, ESA, M. Wong (Space Telescope Science Institute, Baltimore, Md.), H. B. Hammel (Space Science Institute, Boulder, Colo.), and the Jupiter Impact Team

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Jupiter is one of the 5 planets visible with the unaided eye. That means you can go out on a clear night, when Jupiter is up in the sky, and see it with your own eyes. No telescope is necessary. In fact, it’s one of the brightest objects in the sky. When Jupiter is there, it’s hard not to see it. So it’s kind of hard to wonder who discovered Jupiter, since humans would have known about it for tens of thousands of years.

Ancient astronomers didn’t have telescopes, but they knew there was something strange about the planets. They tracked the motion of the planets with incredible accuracy and believed that they were somehow associated with gods in their mythologies. Jupiter is named after the Roman god, thought to be the head of the gods; he’s the same as Zeus in Greek mythology.

Perhaps a better question might be, who discovered Jupiter the planet. In other words, when did astronomers realize that Jupiter was really a planet. That discovery happened when astronomers realized that the Earth was really just a planet as well, orbiting the Sun in the Solar System. The new model for the Solar System was developed by Nicolaus Copernicus in the 16th century. By placing the Sun at the center of the Solar System, Copernicus developed a model that better explained the motions of the planets as they moved through the sky.

This model was confirmed when Galileo pointed his first rudimentary telescope at Jupiter. What he saw was the disk of Jupiter and the 4 largest moons orbiting the planet. Since all the heavenly bodies were thought to orbit the Earth, it was thought to be impossible for objects to orbit one another.

Once astronomers knew that Jupiter was a planet, and they had better telescopes to study it, the exploration of Jupiter could really begin. Better and better images were taken of the planet, and more moons and even rings were discovered orbiting the planet.

And then in the space age, the first spacecraft were sent to explore Jupiter. The first spacecraft to arrive at Jupiter was NASA’s Pioneer 10 in 1973, followed by Pioneer 11 a few months later. These spacecraft returned images of Jupiter’s swirling cloud tops, discovered more about its composition, and revealed features of its moons.

We have written many articles about the discovery of planets in the Solar System. Here’s an article about the discovery of Uranus, and another about the discovery of Neptune.

You can also learn more about Jupiter from NASA’s Solar System Exploration Guide to Jupiter.

We have also recorded an episode of Astronomy Cast all about Jupiter. Listen to it here, Episode 56: Jupiter.

Reference:
NASA

September 16, 2009December 24, 2015 by Fraser Cain

Exosphere

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The Earth’s atmosphere is broken up into several distinct layers. We live down in the troposphere, where the atmosphere is thickest. Above that is the stratosphere, then there’s the mesosphere, thermosphere and finally the exosphere. The top of the exosphere marks the line between the Earth’s atmosphere and interplanetary space.

The exosphere is the outermost layer of the Earth’s atmosphere. It starts at an altitude of about 500 km and goes out to about 10,000 km. Within this region particles of atmosphere can travel for hundreds of kilometers in a ballistic trajectory before bumping into any other particles of the atmosphere. Particles escape out of the exosphere into deep space.

The lower boundary of the exosphere, where it interacts with the thermosphere is called the thermopause. It starts at an altitude of about 250-500 km, but its height depends on the amount of solar activity. Below the thermopause, particles of the atmosphere have atomic collisions, like what you might find in a balloon. But above the thermopause, this switches over to purely ballistic collisions.

The theoretical top boundary of the exosphere is 190,000 km (half way to the Moon). This is the point at which the solar radiation coming from the Sun overcomes the Earth’s gravitational pull on the atmospheric particles. This has been detected to about 100,000 km from the surface of the Earth. Most scientists consider 10,000 km to be the official boundary between the Earth’s atmosphere and interplanetary space.

We have written several articles about the Earth’s atmosphere for Universe Today. Here’s an article about an evaporating extrasolar planet, and this article explains how far away space is.

You can learn more about the layers of the atmosphere, including the exosphere from this page at NASA.

We have recorded a whole episode of Astronomy Cast talking about the Earth’s (and it’s atmosphere). Check it out here, Episode 51: Earth.

September 15, 2009December 24, 2015 by Fraser Cain

Artificial Gravity

An artist's representation of a rotating space station.

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Have you ever noticed that astronauts float around in the space shuttle and in the International Space Station, while space travelers on television and in the movies keep their feet firmly on the ground. That’s because it would be very difficult (and expensive) to have your actors floating around in every scene. So science fiction writers invent some kind of artificial gravity technology, to keep everyone standing on the ground.

Of course, there’s no technology that will actually generate gravity in a spaceship. Gravity only comes from massive object, and there’s no way to cancel the acceleration of gravity. And so if you wanted to have a spacecraft that could generate enough artificial gravity to keep someone’s feet on the ground, the spaceship would need to have the mass of the Earth.

Floating in space is actually very hard on astronauts’ bodies. The lack of gravity softens their bones and causes their muscles to weaken. After any long trip into space, astronauts need several days and even weeks to recover from traveling in microgravity.

But there a couple of ways you could create artificial gravity in a spaceship. The force we feel from gravity is actually our acceleration towards a massive body. We’d keep falling, but the ground is pushing against us, so we stand on the ground. If you can provide an alternative form of acceleration, it would feel like gravity, and provide the same benefits of standing on the surface of a planet.

The first way would be through accelerating your spaceship. Imagine you wanted to fly your spaceship from Earth to Alpha Centauri. You could fire your rockets behind the spacecraft, accelerating at a smooth rate of 9.8 meters/second². As long as the rocket continued accelerating, it would feel like you were standing on Earth. Once the rocket reached the halfway point of its journey, it would turn around and decelerate at the same rate, and once again, you would feel the force of gravity. Of course, it takes an enormous amount of fuel to accelerate and decelerate like this, so we can consider that pretty much impossible.

A second way to create acceleration is to fake it through with some kind of rotation. Imagine if your spaceship was built like a big donut, and you set it spinning. People standing on the inside hull would feel the force of gravity. That’s because the spinning causes a centrifugal force that wants to throw the astronauts out into space. But the spaceship’s hull is keeping them from flying away. This is another way to create artificial gravity.

There are no spacecraft that use any form of artificial gravity today, but if humans do more space exploration, we will likely see the rotational method used in the future.

We have written several articles about artificial gravity for Universe Today. Here’s an article about how mice might be used to test out artificial gravity, and here’s more information about future technologies that might use artificial gravity.

Here’s a podcast from Scientific American that talks about the effect of artificial gravity.

We have recorded an episode of Astronomy Cast that talks about science fiction technologies. Listen to it here: Episode 104 – Science Fiction at Dragon*Con

Sources:
Wikipedia
NEWTON, Ask A Scientist!
Wise Geek

September 15, 2009December 24, 2015 by Fraser Cain

Satellite Map of the World

There’s no better way to appreciate the planet you live on than to have a great big picture of it on your wall. Here are some ways you can get your hands on a satellite map of the world.

If you’ve got a nice printer and you’d like to save yourself some money, why not download a satellite map of the world for free from NASA. You can get free satellite images from the NASA Earth Observatory.

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Each month NASA releases a new composite satellite image of the entire planet. This lets you track changes from month to month. You can view the full images on this page.

You can also get a free satellite map of the world captured at night. This photo shows whole planet Earth, but now you’re seeing it at night. The bright spots are cities and populated areas. It’s easy to see the differences between 1st world countries and more developing nations.

If you want to just buy a poster that you can put on your wall, you can find a bunch of satellite world maps from Amazon.com. Here’s a link to buy the Earth at night poster. And here’s an image of the whole Earth by day.