Astronomy The Facts of Deep Impact!

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Meteors and Meteor Showers: The Science
By Robert Roy Britt

Imagine a baseball zipping along at 30,000 miles per hour. That's how big and fast many meteors are. And though some are bigger than baseballs, most are more like grains of sand. The larger meteors are sometimes broken bits off asteroids or other planets. The small stuff is often dust left by a passing comet.

Entry into the atmosphere
When they plow through the atmosphere, meteors are heated to more than 3000 degrees Fahrenheit, and they glow. Meteors are not heated by friction, as is commonly thought. A phenomenon called ram pressure is at work. A meteor compresses air in front of it. The air heats up, in turn heating the meteor.

The intense heat vaporizes most meteors, creating what we call shooting stars. (Most become visible at around 60 miles up.) Some large meteors splatter, causing a brighter flash called a fireball, and an explosion, which can often be heard up to 30 miles away. When meteors hit the ground, they're called meteorites. Some meteors are bits broken off asteroids, others -- mere cosmic dust -- are cast off by comets. (And one more term: A meteoroid is an object in space that may, if it enters our atmosphere, become a meteor.)


For the complete article please see:
http://www.space.com/scienceastronom...eteors-ez.html

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As much as I love Geology, Astronomy is one category I am very uncomfortable knowing with good cause, its one area, which we are not in the upper hand of the court. Many areas of environmental geology we can prepare or mitigate the dangers Earth’s Fury bestows us. We can closely watch the weathers phenomenon such as Flooding, Droughts, Hurricanes or Tornadic disasters to better notify the public in advance or that we are able to cope with the situation. We are pretty up to date for some predicting of Plate Tectonics such as volcanic eruptions, Earthquakes and thus Tsunamis. Not a “DEEP IMPACT” asteroid collision, to our Blue Planet. The lucky ones will die instantly in this Armageddon, most will endure slow deaths resulting from the collision.

Here is a fun fact: Earths had several direct catastrophic extinction (5 killers to be exact)



THE DINO KILLER
The most commonly discussed is the Chicxulub which hit just off the coast of the Mexican Yucatan peninsula. Through carbon dating the impact we can positively identify the event occurred exactly 65 million years ago and killed off the giant lizards. This asteroid was merely 10 kilometers in diameter, when it slammed into a shallow sea. The resulting crater, called Chicxulub or native for "Tail of the Devil", is about 150 kilometers across! The resulting tsunami would have hit Texas with a wave 50 to 100 meters high. Millions of tons of material were hurled into the atmosphere, causing wildfires across the world as they landed. Rocks fragments called "tektites" formed instantly from droplets of moltenized quartz and are found as far north as Wyoming. A layer of fine dust from this impact can be found in sedimentary rocks throughout the world, marking the boundary between the Cretaceous and Tertiary. Scientists guess that this fine dust blocked sunlight creating darkness for up to 6 months, plants halted growth without the sun’s rays for the cycle of photosynthesis estimated for about 2-12months. Thus the devastating deaths of species went right up the food chain, “The Golden Age of Dinosaurs” came to an end.

[AJE]

Astronomers have obtained the first images of an asteroid on course to make its closest approach to Earth on Tuesday, showing the space rock is lopsided.

FOXNews.com - First Blurry Pictures of Near-Miss Asteroid Released - Science News | Science & Technology | Technology News