Too many trash in Earth made by human, even Space too. Did you know? There are around 13,000 man-made objects in many size (two inches or larger) flying freely in Earth's orbit.
Even in tiny paint flake left floating in orbit can pit the window of Space Shuttle traveling 17,500 miles an hour. To avoid catastrophic collisions, the Department of Defense tracks of orbiting space junk larger than two inches.
Debris orbiting relatively close to Earth, such as glove that drifted away in 1965 from Edward White or an eyebolt shaken loose from solar panel on a Russian Spacecraft in 2004, quickly burns up in the atmosphere. Item is higher orbit remain aloft for generations: The Vanguard 1 satellite will fly for centuries. Space agencies are pondering ways to sweep such us junk out of the path of collisions.
Meanwhile, Australian archaeologist Alice Gorman is lobbying for the creation of an international treaty that would designate certain satellites, such as the Vanguard 1, as treasures of cultural heritage. One day, she says, they may even beckon space tourists.
Thursday, April 17, 2008
The Mistery of Snowflakes
Did you know that snowflake's shape can change itself in different temperature?
That no two snowflakes look exactly alike is fairly common knowledge. Less well known is that snowflake's shape depends on temperature at which it forms. When the mercury hovers between -1 degree centigrade and -3 degrees centigrade, snowflakes crystallize as plates and dendrites.
At about -5 degrees centigrade, needles and hollow columns appear. At still colder temperatures, the flakes design returns to dendrites and plates. And when snowflakes start forming into columns at around -5 degrees centigrade but then encounter cooler or warmer temperatures, the crystals end up as capped columns (part column, part plate).
What no one knows is why temperature affects crystal formation. Kenneth Libbrecht, chair of the physics department at the California Institute of Technology, is trying to solve the mystery by studying thousands of flakes, both in wild, such us Ontario, Michigan, and Alaska, and his lab, where he grows snowflakes under controlled conditions. By comparing snowflake development with theories of crystal growth, he may unlock the secret of how flakes take shape.
According to Libbrecht, the shifting of snowflake may even hold clues to some bigger question of global warming. "Nature is one unstable system haeped on another another," he says. "Knowing where the tipping points are is key to learning if global climate is similar thresholds where sudden changes may occur."
That no two snowflakes look exactly alike is fairly common knowledge. Less well known is that snowflake's shape depends on temperature at which it forms. When the mercury hovers between -1 degree centigrade and -3 degrees centigrade, snowflakes crystallize as plates and dendrites.
At about -5 degrees centigrade, needles and hollow columns appear. At still colder temperatures, the flakes design returns to dendrites and plates. And when snowflakes start forming into columns at around -5 degrees centigrade but then encounter cooler or warmer temperatures, the crystals end up as capped columns (part column, part plate).
What no one knows is why temperature affects crystal formation. Kenneth Libbrecht, chair of the physics department at the California Institute of Technology, is trying to solve the mystery by studying thousands of flakes, both in wild, such us Ontario, Michigan, and Alaska, and his lab, where he grows snowflakes under controlled conditions. By comparing snowflake development with theories of crystal growth, he may unlock the secret of how flakes take shape.
According to Libbrecht, the shifting of snowflake may even hold clues to some bigger question of global warming. "Nature is one unstable system haeped on another another," he says. "Knowing where the tipping points are is key to learning if global climate is similar thresholds where sudden changes may occur."
Ohh No!!!
Karang adalah habitat utama ikan-ikan di laut, terutama pada ikan-ikan yang hidup di perairan yang tidak terlalu dalam yang masih terkena sinar matahari. Tapi apa yang terjadi bila suhu air laut yang terlalu panas memanaskan karang karang yang hidup dan sebagai habitat ikan-ikan di laut itu?
Musim panas tahun 2005 mengakibatkan pemutihan terparah yang pernah terjadi di karang Karibia. kelaikan suhu air laut membuat alga-alga yang membuat karang warna-warni terlepas, membuat warna karan menjadi putih dan akhirnya mati. Hal tersebut terjadi karena alga-alga tersebut merupakan sumber gula dan oksigen bagi karang. Sebaliknya, karang memberi perlindungan dan karbon dioksida bagi alga. Dengan kata lain, mereka memiliki hubungan timbal balik yang saling menguntungkan atau simbiosis mutualisme.
Hal tersebut membuktikan bahwa pemanasan global atau global warming sudah dan sedang terjadi dan telah menimbulkan dampak buruk yang luar biasa. Kata ekolog kelautan Edwin Hernandez-Delado, "Bukti pemanasan global sudah tidak diragukan." Catatan membuktikan bahwa suhu air laut mencapai titik terhangatnya dalam seabad terakhir.
Di Pulau Culebra, Poerto Rico, contohnya, sebanyak 97% koloni yang disurvei, termasuk terumbu karang bintang besar, terputihkan ketika suhu air meninggkat hingga 31,8 derajat Celsius. Hernandez memperkirakan sekiter setengah karang Karibia telah mati pada pertengahan tahun 2006. "Kekacauan seperti ini memiliki kemungkinan untuk lebih sering terjadi," kata Hernandez. Program Lingkungan PBB melaporkan sepertiga karang di Dunia telah mati atau minimal sekarat, dan memprediksikan bahwa 60% dari seluruh karang di Dunia akan musnah pada tahun 2030.
Musim panas tahun 2005 mengakibatkan pemutihan terparah yang pernah terjadi di karang Karibia. kelaikan suhu air laut membuat alga-alga yang membuat karang warna-warni terlepas, membuat warna karan menjadi putih dan akhirnya mati. Hal tersebut terjadi karena alga-alga tersebut merupakan sumber gula dan oksigen bagi karang. Sebaliknya, karang memberi perlindungan dan karbon dioksida bagi alga. Dengan kata lain, mereka memiliki hubungan timbal balik yang saling menguntungkan atau simbiosis mutualisme.
Hal tersebut membuktikan bahwa pemanasan global atau global warming sudah dan sedang terjadi dan telah menimbulkan dampak buruk yang luar biasa. Kata ekolog kelautan Edwin Hernandez-Delado, "Bukti pemanasan global sudah tidak diragukan." Catatan membuktikan bahwa suhu air laut mencapai titik terhangatnya dalam seabad terakhir.
Di Pulau Culebra, Poerto Rico, contohnya, sebanyak 97% koloni yang disurvei, termasuk terumbu karang bintang besar, terputihkan ketika suhu air meninggkat hingga 31,8 derajat Celsius. Hernandez memperkirakan sekiter setengah karang Karibia telah mati pada pertengahan tahun 2006. "Kekacauan seperti ini memiliki kemungkinan untuk lebih sering terjadi," kata Hernandez. Program Lingkungan PBB melaporkan sepertiga karang di Dunia telah mati atau minimal sekarat, dan memprediksikan bahwa 60% dari seluruh karang di Dunia akan musnah pada tahun 2030.
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