Stars

Stars: "Stars

* Protostars
* Bright Stars
* Red Giants
* White Dwarfs



Birth of a Star

Protostars are stars that are about to be born. These are glowing clouds of interstellar gas and dust, which look like dark spots in the midst of light. Gravity causes every atom and every bit of dust to pull on every other one and all move to the center, causing the protostar to collapse. Having begun with a diameter of perhaps 1.5 trillion km, the protostar now shrinks at a very fast rate about 1,000 years, to a diameter of about 80 million km. Because the atoms move faster and faster as they fall toward the center, friction is created as they rub together and the temperature rises. The protostar starts at a temperature of about 100 K and over 1.000 years, rises to about 4,250 K. This heat causes the protostar to glow in with its own light, giving off even more light than our Sun even though it is not nearly as hot. After about 10,000 years, the protostar's surface temperature is up to about 4,500 K and it is now 100 times as luminous as the Sun; after another 100,000 years the temperature is 5,000 K even though the protostar has been shrinking the entire time and only gives off about 10 times the light of the Sun. There is l"...
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Glacier Story

Glacier Story: "A Tour of the Life of a Glacier


Most of the world's glaciers are found near the Poles, but glaciers exist on all of the world's continents, even Africa. Australia doesn't have any glaciers; however, it is considered part of Oceania, which includes several Pacific island chains and the large islands of Papua New Guinea and New Zealand. Both of these islands have glaciers.

Glaciers require very specific climatic conditions. Most are found in regions of high snowfall in winter and cool temperatures in summer. These conditions ensure that the snow that accumulates in the winter isn't lost (by melt, evaporation, or calving) during the summer. Such conditions typically prevail in polar and high alpine regions. There are two main types of glaciers: valley glaciers and continental glaciers (known as ice sheets).

The amount of precipitation (whether in the form of snowfall, freezing rain, avalanches, or wind-drifted snow) is important to glacier survival. In areas such as Antarctica, where the low temperatures are ideal for glacier growth, very low annual precipitation causes the glaciers to grow very slowly.

The glacier story starts with the Growing Years of a glacier."
source:http://www-nsidc.colorado.edu/glaciers/story/
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What is a glacier?

Glaciers are made up of fallen snow that, over many years, compresses into large, thickened ice masses. Glaciers form when snow remains in one location long enough to transform into ice. What makes glaciers unique is their ability to move. Due to sheer mass, glaciers flow like very slow rivers. Some glaciers are as small as football fields, while others grow to be over a hundred kilometers long.

Donjek Glacier in the Saint Elias Range, Yukon Territory, Canada. 1985. (Source: Natural Resources Canada. Photograph by Douglas Hodgson. Copyright Terrain Sciences Division, Geological Survey of Canada.)

Presently, glaciers occupy about 10 percent of the world's total land area, with most located in polar regions like Antarctica and Greenland. Glaciers can be thought as remnants from the last Ice Age, when ice covered nearly 32 percent of the land, and 30 percent of the oceans. An Ice Age occurs when cool temperature endure for extended periods of time, allowing polar ice to advance into lower latitudes. For example, during the last Ice Age, giant glacial ice sheets extended from the poles to cover most of Canada, all of New England, much of the upper Midwest, large areas of Alaska, most of Greenland, Iceland, Svalbard and other arctic islands, Scandinavia, much of Great Britain and Ireland, and the northwestern part of the former Soviet Union.

Within the past 750,000 years, scientists know that there have been eight Ice Age cycles, separated by warmer periods called interglacial periods. Currently, the Earth is nearing the end of an interglacial, meaning that another Ice Age is due in a few thousand years. This is part of the normal climate variation cycle. Greenhouse warming may delay the onset of another glacial era, but scientists still have many questions to answer about climate change. Although glaciers change very slowly over long periods, they may provide important global climate change signals.

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What are Lava Flows?

Lava flows are streams of molten rock that pour or ooze from an erupting vent. Lava is erupted during either nonexplosive activity or explosive lava fountains. Lava flows destroy everything in their path, but most move slowly enough that people can move out of the way. The speed at which lava moves across the ground depends on several factors, including (1) type of lava erupted and its viscosity; (2) steepness of the ground over which it travels; (3) whether the lava flows as a broad sheet, through a confined channel, or down a lava tube; and (4) rate of lava production at the vent.

Fluid basalt flows can extend tens of kilometers from an erupting vent. The leading edges of basalt flows can travel as fast as 10 km/hour on steep slopes but they typically advance less than 1 km/hour on gentle slopes. But when basalt lava flows are confined within a channel or lava tube on a steep slope, the main body of the flow can reach velocities >30 km/hour.

Viscous andesite flows move only a few kilometers per hour and rarely extend more than 8 km from their vents. Viscous dacite and rhyolite flows often form steep-sided mounds called lava domes over an erupting vent. Lava domes often grow by the extrusion of many individual flows >30 m thick over a period of several months or years. Such flows will overlap one another and typically move less than a few meters per hour.

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Map World Forum: A Promise for Sustainable Planet Earth

March 12, 2008 New Delhi, India: After the tremendous success of the first Map World Forum held in
Hyderabad in January 2007, GIS Development, is pleased to announce the dates of the second Map
World Forum, scheduled to be held from February 10-13, 2009 at Hyderabad International Convention Centre, Hyderabad, India. The Forum promises to be a Global Congregation for thought and discussion between experts from various fields like Environment, Finance, Management, Technology and Governance with Geospatial specialists striving to make our planet a sustainable one. It aims to bring the geospatial community into limelight with regards to mainstream development organizations at a global level.

Planet Earth has become susceptible to disasters since the past few decades because of various infrastructure development activities, which has resulted in immense strain on available natural resources.
Keeping in view this background, the theme chosen for the Forum is “Geospatial Technologies for Sustainable Planet Earth”. The factors affecting the sustainability of Planet Earth are all interrelated and in order to combat them, we need to have a tool, which can associate and analyse them in a seamless manner. Geospatial technologies, because of their geospatial information dependent nature, provide the only way to look at these issues from a holistic viewpoint. Today, there exists a notable lack of geographic data and literature on observed changes, with marked scarcity in developing countries. The need of the hour is to build an exhaustive geospatial database that is going to serve as an enabling platform for the various stakeholders of this community. Map World Forum will strive to address this urgent need in order to safeguarded our beautiful planet for our future generations.

The Honorable Minister for Science and Technology & Earth Sciences, Government of India, Kapil Sibal, who is also the Patron of the Forum, states, “Government of India stands committed to create, update, manage and disseminate geospatial information and use it to the best possible manner to improve the quality of the life of its citizens and development of the nation. Keeping this in mind we organized 'Map World Forum' which brought the global leadership in geospatial sciences on one mega platform to discuss the challenges and opportunities for the geospatial science and technology growth and its role for human development in the next decade. Overwhelmed with the need and positive response of such a forum, Government of India is privileged to host the Second Map World Forum”

The Forum has gained the support of Geospatial Industry titan – Rolta India as the Principal Industry Partner. Department of Science and Technology, Government of India is the Principal Government
Partner while Speck Systems is the Corporate Partner for the Forum.

As Affiliate Partners, the Forum already has some key International Societies as its partner organisations -
International Federation of Surveyors (FIG), Geospatial Information Technology Association (GITA),
International Society for Photogrammetry and Remote Sensing (ISPRS) and Open Geospatial Consortium
(OGC).

Map World Forum will be promoted by its Media Partners - Directions Media, GIM International and ASM newsletter in different parts of the world. Directions Media is the premier news and resource guide for geospatial professionals based in the USA. GIM International is the Global Magazine for Geomatics based in The Netherlands and ASM newsletter is an Australian bi-monthly newsletter that reports on events in the spatial industry in Asia. The publishers of ASM newsletter also bring out a magazine for the Australia/New Zealand region specifically, known as Position.

The Technical programme of the Forum will include 12 sub themes for Plenary Addresses, 4 Seminars, 8
Vertical Theme Based Symposia, 20 Technical Sessions, Panel Discussions, Technology Shows, User Meets, Social Programmes and an 1800 sq mtr plus area of Exhibition space. The sub themes for Plenary Addresses have been chosen to cover a wide range of issues. One set of themes cover issues like Climate
Change, Environment, Wildlife and Forest, which reflect the natural environment that is bearing the brunt of modern day lifestyle. The other set of Plenary themes will focus on sectors like Transport, Oil & Gas,
Mining, Energy etc. that need to be in sync with the needs of the environment while contributing simultaneously to economic growth of nations.

The Forum will also host 8 Vertical Theme Based Symposia on different aspects of Geospatial Technology and its applications, like Education, Governance, Social Infrastructure, Petroleum & Mining, Design &
Engineering etc. There will also be two-day Symposium on Location Technologies known as Location Summit.

Sanjay Kumar, the Chief Executive Officer of GIS Development and Convenor of the Forum invites participation of delegates by stating, “Map World Forum will not just be a conference, it will be a Forum that will aim to Converge Ideas and Expand Horizons for Sustainable Planet Earth. It will aim beyond speeches and discussions to find practical ways to protect the Earth and improve people's lives. Its mission, therefore, will be to encourage the geospatial family and the society at large to function in ways that protect the Earth's natural environment and its capacity to provide for the needs and aspirations of present and future generations. I welcome participation of all the individuals and organisations who would like to contribute to this goal for making our planet a better place to live in.”

Source : http://www.MapWorldForum.org

Earthquake Intensity

Earthquake Intensity: "The Modified Mercalli Scale
of Earthquake Intensity
In seismology a scale of seismic intensity is a way of measuring or rating the effects of an earthquake at different sites. The Modified Mercalli Intensity Scale is commonly used in the United States by seismologists seeking information on the severity of earthquake effects. Intensity ratings are expressed as Roman numerals between I at the low end and XII at the high end.

The Intensity Scale differs from the Richter Magnitude Scale in that the effects of any one earthquake vary greatly from place to place, so there may be many Intensity values (e.g.: IV, VII) measured from one earthquake. Each earthquake, on the other hand, should have just one Magnitude, although the several methods of estimating it will yield slightly different values (e.g.: 6.1, 6.3).

Ratings of earthquake effects are based on the following relatively subjective scale of descriptions:"

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Seismic Waves

Seismic Waves: "Seismic Deformation
When an earthquake fault ruptures, it causes two types of deformation: static; and dynamic. Static deformation is the permanent displacement of the ground due to the event. The earthquake cycle progresses from a fault that is not under stress, to a stressed fault as the plate tectonic motions driving the fault slowly proceed, to rupture during an earthquake and a newly-relaxed but deformed state.
Seismic rebound diagram
Typically, someone will build a straight reference line such as a road, railroad, pole line, or fence line across the fault while it is in the pre-rupture stressed state. After the earthquake, the formerly stright line is distorted into a shape having increasing displacement near the fault, a process known as elastic rebound.
Seismic Waves

The second type of deformation, dynamic motions, are essentially sound waves radiated from the earthquake as it ruptures. While most of the plate-tectonic energy driving fault ruptures is taken up by static deformation, up to 10% may dissipate immediately in the form of seismic waves.

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Earthquakes and Plate Tectonics

Earthquakes and Plate Tectonics: "The world's earthquakes are not randomly distributed over the Earth's surface. They tend to be concentrated in narrow zones. Why is this? And why are volcanoes and mountain ranges also found in these zones, too?

An explanation is to be found in plate tectonics, a concept which has revolutionized thinking in the Earth's sciences in the last 10 years. The theory of plate tectonics combines many of the ideas about continental drift (originally proposed in 1912 by Alfred Wegener in Germany) and sea-floor spreading (suggested originally by Harry Hess of Princeton University).

Plate tectonics tells us that the Earth's rigid outer shell (lithosphere) is broken into a mosaic of oceanic and continental plates which can slide over the plastic aesthenosphere, which is the uppermost layer of the mantle. The plates are in constant motion. Where they interact, along their margins, important geological processes take place, such as the formation of mountain belts, earthquakes, and volcanoes.

The lithosphere covers the whole Earth. Therefore, ocean plates are also involved, more particularly in the process of sea-floor spreading. This involves the midocean ridges which are a system of narrow submarine cracks that can be traced down the center of the major oceans. The ocean floor is being continuously pulled apart along these midocean ridges. Hot volcanic material rises"
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