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The Moon and All the Crashes
| Title |
The Moon and All the Crashes |
| Explanation |
A clear blue summer sky finally grows dark and the new telescope, hastily set up in the backyard, generates excitment and anticipation. "I bought it for the kids.", Dad assures himself as he anxiously supervises two young boys' efforts to center a bright, first quarter Moon [ http://tycho.usno.navy.mil/vphase.html ] in the finder. The evening's [ http://www.tufts.edu/as/wright_center/lessons/html/ moon.html ] first target acquired, James adjusts the focus knob and falls silent. Suddenly, "Wow, looks just like on Apollo 13 [ http://antwrp.gsfc.nasa.gov/apod/ap950708.html ]!". His younger brother Christopher takes his turn. "Do you see the Moon [ http://www.salzgeber.at/astro/moon/ index.html ]?", James asks, eager to provide guidance based on his own observing experience. Christopher echoes his brother's enthusiasm, "Yes, and I see all the crashes [ http://antwrp.gsfc.nasa.gov/apod/ap991208.html ] too!". The view they shared was not too different from this image of the seven day old moon, recorded in July 2000 by kids and staff during an observing session at Space Camp [ http://www.spacecampturkey.com/ ] in Izmir, Turkey. Along the terminator, the line between lunar night and day [ http://nssdc.gsfc.nasa.gov/imgcat/html/object_page/ lo4_m123.html ], the shadows outline to advantage the spectacular craters -- caused by all the crashes [ http://antwrp.gsfc.nasa.gov/apod/ap990326.html ]. |
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Tunguska: The Largest Recent
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| Title |
Tunguska: The Largest Recent Impact Event |
| Explanation |
Yes, but can your meteor do this? The most powerful natural explosion [ http://en.wikipedia.org/wiki/Tunguska_event ] in recent Earth history occurred on 1908 June 30 when a meteor exploded [ http://antwrp.gsfc.nasa.gov/apod/ap011118.html ] above the Tunguska River in Siberia [ http://en.wikipedia.org/wiki/Siberia ], Russia [ http://en.wikipedia.org/wiki/Russian_Federation ]. Detonating with an estimated power [ http://en.wikipedia.org/wiki/Tsar_Bomba ] 1,000 times greater than the atomic bomb dropped [ http://en.wikipedia.org/wiki/Atomic_bombings_of_Hiroshima_and_Nagasaki ] over Hiroshima [ http://antwrp.gsfc.nasa.gov/apod/ap071114.html http://en.wikipedia.org/wiki/Hiroshima ], the Tunguska event [ http://antwrp.gsfc.nasa.gov/apod/ap071114.html http://www.psi.edu/projects/siberia/siberia.html ] leveled trees over 40 kilometers away and shook the ground in a tremendous earthquake. Eyewitness reports are astounding. [ http://en.wikipedia.org/wiki/Tunguska_event#Selected_eyewitness_reports ] The above picture was taken by a Russian expedition [ http://www.unmuseum.org/kulik.htm ] to the Tunguska site almost 20 years after the event, finding trees littering the ground like toothpicks. Estimates of the meteor's size range from 60 meters to over 1000 meters in diameter. Recent evidence [ http://news.nationalgeographic.com/news/2007/11/071107-russia-crater.html ] suggests that nearby Lake Cheko [ http://en.wikipedia.org/wiki/Lake_Cheko ] may even have been created by the impact [ http://antwrp.gsfc.nasa.gov/apod/ap990711.html ]. Although a meteor the size of the Tunguska can level a city [ http://www.youtube.com/watch?v=ls0ME-dX08c ], metropolitan areas take up such a small fraction of the Earth's surface that a direct impact on one is relatively unlikely. More likely is an impact in the water [ http://www.space.com/scienceastronomy/astronomy/asteroid_paine_september.html ] near a city that creates a dangerous tsunami [ http://www.youtube.com/watch?v=AlPqL7IUT6M ]. One focus of modern astronomy is to find Solar System objects [ http://neo.jpl.nasa.gov/neo/report2007.html ] capable of creating such devastation well before they impact the Earth. |
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Syrtis Major
PIA03786
Sol (our sun)
Thermal Emission Imaging Sys
…
| Title |
Syrtis Major |
| Original Caption Released with Image |
(Released 1 May 2002) The Science This image is from the region of Syrtis Major, which is dominated by a low-relief shield volcano. This area is believed to be an area of vigorous aeolian activity with strong winds in the east-west direction. The effects of these winds are observed as relatively bright streaks across the image, extending from topographic features such as craters. The brighter surface material probably indicates a smaller relative particle size in these areas, as finer particles have a higher albedo. The bright streaks seen off of craters are believed to have formed during dust storms. A raised crater rim can cause a reduction in the wind velocity directly behind it, which results in finer particles being preferentially deposited in this location. In the top half of the image, there is a large bright streak that crosses the entire image. There is no obvious topographic obstacle, therefore it is unclear whether it was formed in the same manner as described above. This image is located northwest of Nili Patera, a large caldera in Syrtis Major. Different flows from the caldera eruptions can be recognized as raised ridges, representing the edge of a flow lobe. The Story In the 17th century, Holland was in its Golden Age, a time of cultural greatness and immense political and economic influence in the world. In that time, lived a inquisitive person named Christian Huygens. As a boy, he loved to draw and to figure out problems in mathematics. As a man, he used these talents to make the first detailed drawings of the Martian surface - - only 50 years or so after Galileo first turned his telescope on Mars. Mars suddenly became something other than a small red dot in the sky. One of the drawings Huygens made was of a dark marking on the red planet's surface named Syrtis Major. Almost 350 years later, here we are with an orbiter that can show us this place in detail. Exploration lives! It's great we can study this area up close. In earlier periods of history, scientists were fascinated with Syrtis Major because this dark region varied so much through the seasons and years. Some people thought it might be a changing sea, and others thought it might be vegetation. Early spacecraft like Mariner and Viking revealed for the first time that the changes were caused by the wind blowing dust and sand across the surface. What we can see in this image is exactly that: evidence of a lot of wind action. Bright dust patches streak across this image, formed through wind interference from craters and other landforms. These wispy, bright streaks are spread on the surface by a vigorous, east-west wind that kicked up huge dust storms, scattering the fine particles of sand and dust in an almost etherial pattern. The bright streaks in the top part of the image might have formed in a slightly different way, because there is no landform standing in the wind's way. Beneath the bright surface dust are raised ridges that mark the edges of earlier lava flows, from Nili Patera, a Martian "caldera." A caldera is a collapsed, bowl-shaped depression at the top of a volcano cone. Can you imagine how Christian Huygens would feel if he lived today and could see all of this knowledge unfold? Or how it would feel to be the first person to stand in this dark volcanic and cratered region, knowing how many discovers had paved the way to that moment? Yes, exploration lives! |
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Syrtis Major
PIA03786
Sol (our sun)
Thermal Emission Imaging Sys
…
| Title |
Syrtis Major |
| Original Caption Released with Image |
(Released 1 May 2002) The Science This image is from the region of Syrtis Major, which is dominated by a low-relief shield volcano. This area is believed to be an area of vigorous aeolian activity with strong winds in the east-west direction. The effects of these winds are observed as relatively bright streaks across the image, extending from topographic features such as craters. The brighter surface material probably indicates a smaller relative particle size in these areas, as finer particles have a higher albedo. The bright streaks seen off of craters are believed to have formed during dust storms. A raised crater rim can cause a reduction in the wind velocity directly behind it, which results in finer particles being preferentially deposited in this location. In the top half of the image, there is a large bright streak that crosses the entire image. There is no obvious topographic obstacle, therefore it is unclear whether it was formed in the same manner as described above. This image is located northwest of Nili Patera, a large caldera in Syrtis Major. Different flows from the caldera eruptions can be recognized as raised ridges, representing the edge of a flow lobe. The Story In the 17th century, Holland was in its Golden Age, a time of cultural greatness and immense political and economic influence in the world. In that time, lived a inquisitive person named Christian Huygens. As a boy, he loved to draw and to figure out problems in mathematics. As a man, he used these talents to make the first detailed drawings of the Martian surface - - only 50 years or so after Galileo first turned his telescope on Mars. Mars suddenly became something other than a small red dot in the sky. One of the drawings Huygens made was of a dark marking on the red planet's surface named Syrtis Major. Almost 350 years later, here we are with an orbiter that can show us this place in detail. Exploration lives! It's great we can study this area up close. In earlier periods of history, scientists were fascinated with Syrtis Major because this dark region varied so much through the seasons and years. Some people thought it might be a changing sea, and others thought it might be vegetation. Early spacecraft like Mariner and Viking revealed for the first time that the changes were caused by the wind blowing dust and sand across the surface. What we can see in this image is exactly that: evidence of a lot of wind action. Bright dust patches streak across this image, formed through wind interference from craters and other landforms. These wispy, bright streaks are spread on the surface by a vigorous, east-west wind that kicked up huge dust storms, scattering the fine particles of sand and dust in an almost etherial pattern. The bright streaks in the top part of the image might have formed in a slightly different way, because there is no landform standing in the wind's way. Beneath the bright surface dust are raised ridges that mark the edges of earlier lava flows, from Nili Patera, a Martian "caldera." A caldera is a collapsed, bowl-shaped depression at the top of a volcano cone. Can you imagine how Christian Huygens would feel if he lived today and could see all of this knowledge unfold? Or how it would feel to be the first person to stand in this dark volcanic and cratered region, knowing how many discovers had paved the way to that moment? Yes, exploration lives! |
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