Guide to Space Archives

September 26, 2010December 24, 2015 by Tega Jessa

What Galaxy Do We Live In?

Artist's impression of The Milky Way Galaxy. Based on current estimates and exoplanet data, it is believed that there could be tens of billions of habitable planets out there. Credit: NASA

If you are not an astronomy enthusiast you not have thought much about what galaxy do we live in. So depending on that the answer may surprise you. If you know anything about galaxies you know that they are groupings of stars that number in the hundreds of billions. The most famous is the Milky Way. It is from this galaxy that we even have the term. The simple point is that the Earth is part of the Milky Way even though if we see it in the sky it looks like we are observing it from the outside. Why is that? To understand you need to know exactly where we live in neighborhood of the Milky Way Galaxy.

As we are part of the solar system Earth pretty much follows the path of the sun as it goes through its own orbit around the galaxy. The Milky Way is a spiral galaxy type so it has arms sort of like an octopus. The Sun is located near the outward tip of the Sagittarius arm of the Milky Way. This makes Earth about 28,000 light years from the galactic core of our home galaxy.

The Solar System also has a galactic year that it follows. It takes around 200 million to 250 million years for the solar system to orbit the Sun. Another indicator of our position is where the galactic equator. While our star system is considered to be on the outskirts of the Milky Way this is only an estimate. It is believed that the Milky Way is larger than first estimated. There is also suspicion that our galaxy is in the process of absorbing other smaller galaxies. However, there is not enough empirical evidence available to support the claim.

So what would be so important about knowing what part of the galaxy we live in? One reason is space exploration. Some time in the future mankind may find a way to achieve faster than light space travel. This can provide a new set of challenges for engineers and astronomers to tackle. For example how would an astronaut keep from getting lost in space? Detailed mapping and computer programming in the future could help galactic wayfarers know where they are going and more importantly how to get home.

The other reason is that it never hurts to know our place in the scheme of things. Just thinking of the challenge of finding earth if we were so far way helps us to understand how truly vast the universe is.

We have written many articles about the Milky Way galaxy for Universe Today. Here are some facts about the Milky Way, and here’s an article about the closest galaxy to the Milky Way.

If you’d like more info on galaxies, check out Hubblesite’s News Releases on Galaxies, and here’s NASA’s Science Page on Galaxies.

We’ve also recorded an episode of Astronomy Cast about galaxies. Listen here, Episode 97: Galaxies.

Sources: SEDS, Daily Galaxy

September 22, 2010December 24, 2015 by Jerry Coffey

What Is Water Made Of

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The answer to ‘what is water made of’ is as easy as you want it to be. Do you want to just do some superficial research or do you want to look a little deeper? Superficially, pure, distilled water is composed of 2 hydrogen atoms and 1 oxygen atom. If the sample of water is not ‘pure’, the composition of the sample can be different.

Salt water obviously contains salt, but it can contain many other trace elements. Fresh water from different sources will contain different elements and minerals. These come from the rocks the water washes over and the pollutants from farms and industry. The water that you drink will contain several additives used for purification plus the fluoride that is added for our health. Rain water will have any number of pollutants that have accumulated in the atmosphere.

At high temperatures and pressures, like those in the interior of giant planets, scientists think that water exists as ionic water in which the molecules break down into a soup of hydrogen and oxygen ions, and at even higher pressures as superionic water in which the oxygen crystallizes but the hydrogen ions float around freely within the oxygen lattice.

There are many interesting facts about water. Water is a tasteless, odorless liquid. The natural color of water and ice is slightly blue, although water appears colorless in small quantities. Ice also appears colorless, and water vapor is essentially invisible as a gas. Since the water molecule is not linear and the oxygen atom has a higher electronegativity than hydrogen atoms, water carries a slight negative charge. As a result, water has a electrical dipole moment. Water can form a large number of intermolecular hydrogen bonds(four). These factors lead to to water’s high surface tension and capillary forces. Water is often referred to as the universal solvent. All major cellular components are dissolved in water. Water is at its maximum density at 3.98°C. Oddly, it becomes less dense when it is cooled down to its solid form, ice. It expands to occupy 9% greater volume in this solid state, which accounts for the fact of ice floating on liquid water.

Water covers the majority of our planet and can be found in one form or another throughout the known universe. No matter where you are on Earth, water affects you in some way each day.

We have written many articles about water for Universe Today. Here’s an article about the density of water, and here’s an article about the water on Earth.

If you’d like more info on Water, check out NASA’s Water, Water, Everywhere!. And here’s a link to NASA’s Earth Observatory.

We’ve also recorded an episode of Astronomy Cast all about planet Earth. Listen here, Episode 51: Earth.

Source: Wikipedia

September 20, 2010January 7, 2017 by Matt Williams

What is Carbon Dioxide?

CO2 is more than just the stuff that comes out of smokestacks, tailpipes, cigarettes and campfires. It is also a crucial element here on planet Earth, essential to life and its processes. It is used by plants to make sugars during photosynthesis. It is emitted by all animals, as well as some plants, fungi and microorganisms, during respiration. It is used by any organism that relies either directly or indirectly on plants for food; hence, it is a major component of the Carbon Cycle. It is also a major greenhouse gas, hence why it is so closely associated with Climate Change.

Joseph Black, a Scottish chemist and physician, was the first to identify carbon dioxide in the 1750s. He did so by heating calcium carbonate (limestone) with heat and acids, the result of which was the release of a gas that was denser than normal air and did not support flame or animal life. He also observed that it could be injected into calcium hydroxide (a liquid solution of lime) to produce Calcium Carbonate. Then, in 1772, another chemist named Joseph Priestley came up with of combining CO2 and water, thus inventing soda water. He was also intrinsic in coming up with the concept of the Carbon Cycle.

Since that time, our understanding of CO2 and its importance as both a greenhouse gas and an integral part of the Carbon Cycle has grown exponentially. For example, we’ve come to understand that atmospheric concentrations of CO2 fluctuate slightly with the change of the seasons, driven primarily by seasonal plant growth in the Northern Hemisphere. Concentrations of carbon dioxide fall during the northern spring and summer as plants consume the gas, and rise during the northern autumn and winter as plants go dormant, die and decay.

Traditionally, atmospheric CO2 levels were dependent on the respirations of animals, plants and microorganisms (as well as natural phenomena like volcanoes, geothermal processes, and forest fires). However, human activity has since come to be the major mitigating factor. The use of fossil fuels has been the major producer of CO2 since the Industrial Revolution. By relying increasingly on fossil fuels for transportation, heating, and manufacturing, we are threatening to offset the natural balance of CO2 in the atmosphere, water and soil, which in turn is having observable and escalating consequences for our environment. As is the process of deforestation which deprives the Earth of one it’s most important CO2 consumers and another important link in the Carbon Cycle.

As of April 2010, CO2 in the Earth’s atmosphere is at a concentration of 391 parts per million (ppm) by volume. For an illustrated breakdown of CO2 emissions per capita per country, click here.

We have written many articles about Carbon Dioxide for Universe Today. Here’s an article about the Carbon Cycle Diagram, and here’s an article about Greenhouse Effect.

If you’d like more info on Carbon Dioxide, check out NASA’s The Global Climate Change. And here’s a link to The Carbon Cycle.

We’ve also recorded an episode of Astronomy Cast all about planet Earth. Listen here, Episode 51: Earth.

Sources:
http://en.wikipedia.org/wiki/Carbon_dioxide
http://en.wikipedia.org/wiki/Carbon_cycle
http://www.eoearth.org/article/carbon_dioxide
http://cdiac.ornl.gov/
http://www.epa.gov/climatechange/emission/co2.html
http://www.lenntech.com/carbon-dioxide.htm
http://www.davidsuzuki.org/issues/climate-change/science/climate-change-basics/climate-change-101-1/

September 19, 2010December 24, 2015 by Tega Jessa

What are the Steps of the Scientific Method

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The scientific method is the important process by which all scientific knowledge is acquired. It is a tried and tested method that has been refined over the centuries leading to ever greater discoveries and a better understanding of the universe around us.

The scientific method began with the rules of logic established by the Greek philosopher Aristotle. Over time other philosophers and scientists improved on his work refining the process of inquiry and proving of theories and hypotheses. The current version of the method is 6 to 8 steps depending on whether you are looking to explain an observed phenomenon, coming up with new methods, or integrating old information.

The first step is to define the question. You look at the problem you are trying solve or the phenomena you are trying to understand and formulate a question that can get a solution. This step is the most important as asking the right question is more likely to lead you to the right answer.

The next step is to collect data and observe. This is the part where you either study previous bodies of knowledge or observe the phenomena for the first set of clues needed to find the answer to your question. Observation when done properly will draw your attention to information you may miss at the first glance.

The proceeding step is to form a hypothesis. This is your preliminary explanation of the answer to your question. If you are answering the question of whether an atom is divisible you would look at data of previous scientist observe an atom and make an initial hypothesis. You can say that given the data that the unique characteristics of different atoms must mean that atoms are made up of smaller particles that determine its differing properties.

After the hypothesis are experimentation and more data collection. You find a premise or test to prove or disprove your hypothesis. In the case of whether an atom is made up of smaller particles we can use the example of Rutherford Hayes polonium experiment. He used a radioactive material in the form of cathode rays to bombard a material to see if it was altered.

Data Analysis immediately follows your experiment. You look at the data to see if you found new clues. Depending on the data you may find evidence that proves or disproves your hypothesis.

You finally draw a conclusion and see if the data supports your hypothesis or if you need to remodel it. This step often has scientists restarting the process so they can better refine their hypothesis or try a new approach.

The final two steps involve publishing your findings and retesting where other scientists as well as yourself retest and experiment to see if the hypothesis holds up in all cases. Many times this can lead to the discovery of exception on theories and natural laws.

We have written many articles about scientific methods for Universe Today. Here’s a podcast about The Scientific Method, and here are some Science Fair Ideas.

If you’d like more info on the Scientific Methods, check out NASA’s Scientific Method Article. And here’s a link to Problem Solving Using the Scientific Method.

We’ve also recorded an episode of Astronomy Cast all about the Scientific Method. Listen here, Episode 90: The Scientific Method.

Source: How Stuff Works

September 19, 2010December 24, 2015 by Tega Jessa

What are Photons

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When we think about light we don’t really think about what it is made of. This was actually the subject one of the most important arguments in physics. For the longest time physicists and scientist tried to determine if light was a wave or a particle. There were the physicists of the eighteenth century who strongly believed that light was made of basic units , but certain properties like refraction caused light to be reclassified as a wave. It would take no less than Einstein to resolve the issue. Thanks to him and the work of other renowned physicists we know more about what are photons.

To put it simply photons are the fundamental particle of light. They have a unique property in that they are both a particle and a wave. This is what allows photons unique properties like refraction and diffusion. However light particles are not quite the same as other elementary particles. They have interesting characteristics that are not commonly observed. First, as of right now physicists theorize that photons have no mass. They have some characteristics of particles like angular momentum but their frequency is independent of the influence of mass They also don’t carry a charge.

Photons are basically the most visible portion of the electromagnetic spectrum. This was one of the major breakthroughs Einstein and the father of quantum physics, Planck made about the nature of light. This link is what is behind the photoelectric effect that makes solar power possible.Because light is another form of energy it can be transferred or converted into other types. In the case of the photoelectric effect the energy of light photons is transferred through the photons bumping into the atoms of a giving material. This causes the atom that is hit to lose electrons and thus make electricity.

As mentioned before photons played a key role in the founding of quantum physics. The study of the photons properties opened up a whole new class of fundamental particles called quantum particles. Thanks to photons we know that all quantum particles have both the properties of waves and particles. We also know that energy can be discretely measured on a quantum scale.

Photons also played a big role in Einstein’s theory of relativity. without the photon we would not understand the importance of the speed of light and with it the understanding of the interaction of time and space that it produced. We now know that the speed of light is an absolute that can’t be broken by natural means as it would needs an infinite amount of energy something that is not possible in our universe. So without the photon we would not have the knowledge about our universe that we now possess.

We have written many articles about photons for Universe Today. Here’s an article about how the sun shines, and here’s an article about why stars shine.

If you’d like more info on Photons, check out the Mass of the Photon. And here’s a link to an article about How Gravity Affects Photons.

We’ve also recorded an episode of Astronomy Cast all about the Atom. Listen here, Episode 164: Inside the Atom.

Source:
Wikipedia

September 19, 2010December 24, 2015 by Tega Jessa

What Color is the Sky

Space Travel — Atlantis Breaks Through the Clouds

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If you are a parent or are old enough to babysit younger relatives there is one question children ask that stumps most adults. It’s what color is the sky or why is the sky blue. This article will tell you why and do it in as simple a way as possible so that the next time a kids ask the question you have a good answer.

To understand why the sky is blue you need to remember how color works. Color is largely caused by how well an object absorbs the light spectrum. When you see a blue sky you only see blue because all the other colors were absorbed in the air. Any object with color works that way. For example a red ball is read because all the colors of light are absorbed by the ball except for red. This reflected light is what gives the object color.

This is what happens with the sky. The atmosphere is denser than we imagine and the different gases give the atmosphere unique properties in how it absorbs, diffuses, and reflects light. When sunlight passes through our atmosphere a portion of it is scattered and absorbed. The remainder either reaches the surface or is reflected back. The portion that makes it to us observers is 75 percent.

This process is called diffused sky radiation. So to review, we color because objects due to texture of dyes and surfaces absorb all light wavelengths and reflect back one or more. The reason we see the sky as blue is because the molecules in the air scatter the light absorbing most wavelengths of light except for blue.

In addition to this the sky is gray and overcast because of the water droplets in the atmosphere in the forms of clouds and humidity. water refracts light equally unlike air molecules in the atmosphere. This means we get the entirety of white light only it is dimmer just like when you shine a light through a white sheet.

The fact we see a blue sky is good thing because its shows that are atmosphere is at work shielding us from the full energy of the sun’s rays. While the sun is the largest source of energy to our planet, a lot of its high energy radiation that is deadly for living things. Our atmosphere plays it part by shielding us from that. So when you see a blue sky with your kid you can tell them it means the sky is acting like a huge shade blocking out the bad parts of the sun.

We have written many articles about the earth’s sky for Universe Today. Here’s an article about why the sky is blue, and here’s an article about how to find Venus in the sky.

If you’d like more info on the earth’s sky, check out an article about Strange Clouds. And here’s a link to NASA Space Place Article on Blue Sky.

We’ve also recorded an episode of Astronomy Cast all about Sky Survey. Listen here, Episode 118: Sky Surveys.

September 17, 2010December 24, 2015 by Jerry Coffey

What Is The Largest Island In The World

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If you were asked what is the largest island in the world, what would you say? Australia maybe? Greenland is the worlds largest island. While Australia is an island, it is considered a continent. Greenland has an area of 2,166,086 square km, but a meager population of 56,452. The populations is over 85% Inuit. The remaining inhabitants are mainly Danish. The average annual temperature of Greenland varies between -9 to 7 °C.

Greenland is an autonomous country within the Kingdom of Denmark. Greenland is a group of islands and Greenland is the name of the largest, most populated one. Greenland has been inhabited on and off since 2500 BC. Denmark established rule in the 18th century. In 1979 Denmark granted home rule, in a relationship known as the Commonwealth of the Realm and in 2008 Greenland voted to transfer more powers to the local government. The Danish royal government is only in charge of foreign affairs, security, financial policy, and providing a subsidy to each citizen.

Greenland is bordered by the Atlantic Ocean to the southeast, the Greenland Sea to the east, the Artic Ocean to the north, and Baffin Bay to the west. The nearest countries to Greenland are Iceland to the east and Canada to the west. The country also contains the world’s largest national park. Scientists have thought for decades that the ice sheet covering the country may actually conceal three separate island land masses that have been bridged by glaciers over the last geologic cooling period.

The Greenland ice sheet covers 1,755,637 square km. It has a volume of 2,850,000 cubic km. Gunnbjorn Fjeld is the highest point on Greenland at 3,700 m. The majority of Greenland is less than 1,500 m in elevation. The weight of the ice sheet has formed a basin that is more than 300 m below sea level.

Between 1989 and 1993, climate researchers drilled into the summit of Greenland’s ice sheet, obtaining a pair of 3 km ice cores. Analysis of the layering and chemical composition of the cores has provided a revolutionary new record of climate change going back about 100,000 years. It illustrated that the world’s weather and temperature have often shifted rapidly from one stable state to another. The glaciers of Greenland are also contributing to a rise in the global sea level at a faster rate than was previously believed.

Greenland is fascinating and intimidating at the same time. To live there is a daily struggle against the elements that has forged a tough people.

We have written many articles about Greenland for Universe Today. Here’s an article about the growing ice sheets in Greenland, and here are some images of Greenland from space.

If you’d like more info on Earth’s islands, check out NASA’s Solar System Exploration Guide on Earth. And here’s a link to NASA’s Earth Observatory.

We’ve also recorded an episode of Astronomy Cast all about planet Earth. Listen here, Episode 51: Earth.

Sources:
World Atlas
Geographia

September 17, 2010December 24, 2015 by Jerry Coffey

What Is The Largest Continent

Asia Image Credit: NASA's Blue Marble project

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There are a few different ways to answer ‘what is the largest continent’. The first is by area and another is by population. By area, Asia is the largest continent at 44,391,162 square km. It is also the largest by population with more than 4 billion people.

There is quite a bit of debate as to how many continents there are. Some areas of the world combine Asia and Europe into one continent called Eurasia. In that case, the continent of Eurasia would be the biggest continent in both area and population.

The debate as to how many continents there are is based in the basic, yet confusing definition of what a continent is. A continent is understood to be large, continuous, discrete mass of land, ideally separated by an expanse of water. Many of the seven most commonly recognized continents identified by convention are not discrete landmasses separated by water. The criteria of being large is used arbitrarily. Greenland has an area of 2,166,086 square km and is considered an island. Australia has an area of 7,617,930 square km, but it is called a continent. The distinct landmass separated by water criteria is sometimes ignored in the case of Europe and Asia. All of the criteria are a consensus, not a rule, so some countries teach a different number of continents.

Whether you have been taught that there are 6 or 7 continents, you need to know that here have been changing numbers of continents since the formation of the Earth. There have been anywhere from 1 to 7 continents. As the tectonic plates have shifted, the continents have broken apart and collided together again. The Earth’s tectonic plates are still moving, so it is hard to predict how many continents there will be in 500,000 years, 1 million years, and so forth.

The answer to ‘what is the largest continent’ is pretty cut and dry. If you consider that there are seven continents, then Asia is the largest in area and population. If you combine Europe and Asia into the continent of Eurasia, it is still the largest by area and population.

We have written many articles about Continent for Universe Today. Here’s an article about the number of continents in the Earth, and here’s an article about the Continental Drift Theory.

If you’d like more info on continents, check out NASA’s Solar System Exploration Guide on Earth. And here’s a link to NASA’s Earth Observatory.

We’ve also recorded an episode of Astronomy Cast all about planet Earth. Listen here, Episode 51: Earth.

Source:
Wikipedia

September 17, 2010December 24, 2015 by Matt Williams

What is Boyle’s Law

It is interesting to think that at this very moment all of us, every living terrestrial organism, are living in a state of pressure. We normally don’t feel it the human body is primarily made up of liquid, and liquids are basically non compressible. At times, however, we do notice changes of pressure, primarily in our ears. This is often described as a “pop” and it occurs when our elevation changes, like when we fly or driving in the mountains. This is because our ears have an air space in them, and air, like all other gases, is compressible.

Robert Boyle was one of the first people to study this phenomena in 1662. He formalized his findings into what is now called Boyle’s law, which states that “If the temperature remains constant, the volume of a given mass of gas is inversely proportional to the absolute pressure” Essentially, what Boyle was saying is that an ideal gas will compress proportionately to the amount of pressure exerted on it. For example, if you have a 1 cubic meter balloon and double the pressure on it, it will be compressed to ½ a cubic meter. Increase the pressure by 4, and the volume will drop to 1/4 of its original size, and so on.

The law can also be stated in a slightly different manner, that the product of absolute pressure (p) and volume (V) is always constant (k); p x V = k, for short. While Boyle derived the law solely on experimental grounds, the law can also be derived theoretically based on the presumed existence of atoms and molecules and assumptions about motion and that all matter is made up of a large number of small particles (atoms or molecules) all of which are in constant, motion. These rapidly moving particles constantly collide with each other and with the walls of their container (also known as the kinetic theory).

Another example of Boyle’s law in action is in a syringe. In a syringe, the volume of a fixed amount of gas is increased by drawing the handle back, thereby lessening the pressure. The blood in a vein has higher pressure than the gas in the syringe, so it flows into the syringe, equalizing the pressure differential. Boyle’s law is one of three gas laws which describe the behavior of gases under varying temperatures, pressures and volumes. The other two laws are Gay-Lussac’s law and Graham’s law. Together, they form the ideal gas law.

For an animated demonstration of Boyle’s Law, click here.

We have written many articles about Boyle’s Law for Universe Today. Here’s an article about air density, and here’s an article about the Boltzmann Constant.

If you’d like more info on Boyle’s Law, check out NASA’s Boyle’s Law Page, and here’s a link to the Boyle’s Law Lesson.

We’ve also recorded an episode of Astronomy Cast. Listen here, Question Show: The Source of Atmospheres, The Vanishing Moon and A Glow After Sunset.

Sources:
http://en.wikipedia.org/wiki/Boyle%27s_law
http://en.wikipedia.org/wiki/Ideal_gas
http://www.chm.davidson.edu/vce/gaslaws/boyleslaw.html
http://home.flash.net/~table/gasses/boyle1.htm
http://www.wisegeek.com/what-is-boyles-law.htm
http://www.grc.nasa.gov/WWW/K-12/airplane/boyle.html

September 17, 2010December 24, 2015 by Matt Williams

Atomic number

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Ever wonder why the periodic table of elements is organized the way it is? Why, for example, does Hydrogen come first? And just what are these numbers that are used to sort them all? They are known as the element’s atomic number, and in the periodic table of elements, the atomic number of an element is the same as the number of protons contained within its nucleus. For example, Hydrogen atoms, which have one proton in their nucleuses, are given an atomic number of one. All carbon atoms contain six protons and therefore have an atomic number of 6. Oxygen atoms contain 8 protons and have an atomic number of 8, and so on. The atomic number of an element never changes, meaning that the number of protons in the nucleus of every atom in an element is always the same.

Arranging elements based on their atomic weight began with Ernest Rutherford in 1911. It was he who first suggested the model for an atom where the majority of its mass and positive charge was contained in a core. This central charge would be roughly equal to half of the atoms total atomic weight. Antonius van den Broek added to this by formerly suggesting that the central charge and number of electrons were equal. Two years later, Henry Moseley and Niels Bohr made further contributions that helped to confirm this. The Bohr model of the atom had the central charge contained in its core, with its electrons circulating it in orbit, much like how the planet in the solar system orbit the sun. Moseley was able to confirm these two hypotheses through experimentation, measuring the wavelengths of photon transitions of various elements while they were inside an x-ray tube. Working with elements from aluminum (which has an atomic number thirteen) to gold (seventy nine), he was able to show that the frequency of these transitions increased with each element studied.

In short, the higher the atomic number (aka. the higher the number of protons), the heavier the element is and the lower it appears on the periodic table. The atomic number of an element is conventionally represented by the symbol Z in physics and chemistry. This is presumably derived from the German word Atomzahl, which means atomic number in English. It is not to be confused with the mass number, which is represented by A. This corresponds to the combined mass of protons and neutrons in the element.

We have written many articles about the atomic number for Universe Today. Here’s an article about the atomic nucleus, and here’s an article about the Atom Models.

If you’d like more info on the Atomic Number, check out NASA’s Atoms and Light Energy Page, and here’s a link to NASA’s Atomic Numbers and Multiplying Factors Page.

We’ve also recorded an entire episode of Astronomy Cast all about the Atom. Listen here, Episode 164: Inside the Atom.

Sources:
NDT Resource Center
Jefferson Lab
Wise Geek
Wiki Answers