时间:2019-01-23 作者:英语课 分类:探索与发现2014年


英语课

 Most of the damage from an explosion like this is actually the blast wave. It’s the very high winds. Mark created a simulation to see what size an asteroid 1 would need to be to be able to generate such destructive power. 


 
In this simulation I include more of the physics to be more realistic. We can see that the main shockwave doesn’t come out of the point of the explosion, but it comes out of the point where the fireball descends 2 to. So by the time the shockwave gets to the ground, it’s much stronger than it would otherwise be. And there’s more damage on the ground because the destructive power was carried downward. 
 
Based on Mark’s calculations, the devastation 3 at Tunguska could have been caused by an asteroid, perhaps as small as 30 to 50 metres in diameter, and this carries a worrying implication. Smaller asteroids 4 are more dangerous than we used to think and because there are so many more smaller asteroids than bigger asteroids we need to take that risk more seriously than we used to. 
 
The lesson of Tunguska helps explain why in Chelyabinsk there’s so much damage, but very little meteorite 5 to be found. 
 
If we go back to the video footage and we see the object coming in when it’s in the high atmosphere, it suffers very little effect, but just here you get this huge flare-up and that’s because the atmosphere has become so dense 6 that it’s almost impossible for it to push through any more. And basically something’s got to give and the asteroid gives, and it basically just breaks apart in a huge catastrophic fragmentation event. And that is what creates a shockwave which we hear as this sonic boom. 
 

n.小行星;海盘车(动物)
  • Astronomers have yet to witness an asteroid impact with another planet.天文学家还没有目击过小行星撞击其它行星。
  • It's very unlikely that an asteroid will crash into Earth but the danger exists.小行星撞地球的可能性很小,但这样的危险还是存在的。
v.下来( descend的第三人称单数 );下去;下降;下斜
  • This festival descends from a religious rite. 这个节日起源于宗教仪式。 来自《简明英汉词典》
  • The path descends steeply to the village. 小路陡直而下直到村子。 来自《简明英汉词典》
n.毁坏;荒废;极度震惊或悲伤
  • The bomb caused widespread devastation. 炸弹造成大面积破坏。
  • There was devastation on every side. 到处都是破坏的创伤。 来自《简明英汉词典》
n.小行星( asteroid的名词复数 );海盘车,海星
  • Asteroids,also known as "minor planets",are numerous in the outer space. 小行星,亦称为“小型行星”,在外太空中不计其数。
  • Most stars probably have their quota of planets, meteorids, comets, and asteroids. 多数恒星也许还拥有若干行星、流星、彗星和小行星。
n.陨石;流星
  • The meteorite in Jilin Exhibition Hall is believed to be the largest in the world.吉林展览馆的陨石被认为是世界上最大的。
  • The famous Murchison meteorite smashed into the Australian ground in 1969.1969年著名的默奇森陨石轰然坠落在澳大利亚。
a.密集的,稠密的,浓密的;密度大的
  • The general ambushed his troops in the dense woods. 将军把部队埋伏在浓密的树林里。
  • The path was completely covered by the dense foliage. 小路被树叶厚厚地盖了一层。
学英语单词
abak
acutely aware
aformers
air flask
anatectic earthquake
at one's own expense
bakers creek
bashkir
caballeros
call processing tasks
capacitor bushing
cavalierness
central rectrice
centrifugal refrigerating machine
cff (compressibility of formation fluid)
characteristic ion
cladoxylopsids
compacting by high explosive
Denkyera
disulfide group
double limit
dry abrasive cloth
dual-catalyst
Durandal
dyll
ecoalarmist
entered tonnage
epinephelus flavocaeruleus
epiparietals
equipotential contour
ethylenediaminetetra-acetic acid
experimental development
father-of-six
Filago spathulata
film recording thermograph
fisetin
gate channel for repairing
gonatalgia
hand dressing
Hayama
hook conveyer
huvud
hydraulic-transmission
Indian relish
infra-median vein
kilerg
lateral meniscus
LHN
low carbon alloy
Lygodium palmatum
malaria survey
management training
mantodean
meganiche
merging data
merlon
middle meningeal artery
milk-shake
molecular equation
Mycoderma cerevisiae Hansen
National Petroleum Association
neutraling value
one-piece film
parallel association processor
pecorans
pelini
Pibul Songgram
pishamin
pointing out
prayerbooks
preplacode
private branch exchange,PBX
progermination
propellant outage
prox. acc
pseudo-operations
rapturizes
removing of the needle
rhusflavone
rozhdestvensky
safety mechanism
sarcoma virus
schmidt cameras
Sekenke
sequential buffering
silent status
slider control
smoot-hawleys
stabilized condition
start - up loan
status filters
subject(to)
teacup dog
tecla
thin silk
tidal observations
Torilis scabra
trabeate
tractor binder
unitary gas conversion process
untameably
Zcat