时间:2019-02-16 作者:英语课 分类:英语听力文摘 English Digest


英语课

  If you find yourself away from a city, spend an hour looking up on any clear, moonless night.

You're bound to see a few brilliant "shooting stars." These actually have nothing to do with stars: They're meteors, and if your viewing conditions are good, you can see about seven per hour on any given night.

During a "meteor shower" however, this rate may increase to over a hundred meteors an hour. What are meteors, and what makes them gather into showers?

Meteors are caused by bits of rocky material that enter our atmosphere from space, then burn up because of friction 1. They don't have to be big for you to see them. Surprisingly, most visible meteors are caused by debris 2 no larger than a single grain of sand. They burn so brightly because of tremendous friction when they hit our atmosphere at more than forty miles per second.

Why would something as random 3 as flying specks 4 of space debris gather into showers? It's because the Earth passes through the same regions of space each time it orbits the sun. Certain regions have more debris than others, so we have meteor showers on those nights.

Of course this raises the question of why certain parts of our orbit would be especially full of debris. The answer has to do with comets. Comets are big, dirty snowballs that orbit our sun. Long after a comet and it's tail have passed us by, it leaves behind a thin trail of dust and debris. If a comet crosses the Earth's orbit, we pass through this trail each year. For example, every October twenty-first we pass through the Orionid shower, which is debris left behind from Halley's comet.



n.摩擦,摩擦力
  • When Joan returned to work,the friction between them increased.琼回来工作后,他们之间的摩擦加剧了。
  • Friction acts on moving bodies and brings them to a stop.摩擦力作用于运动着的物体,并使其停止。
n.瓦砾堆,废墟,碎片
  • After the bombing there was a lot of debris everywhere.轰炸之后到处瓦砾成堆。
  • Bacteria sticks to food debris in the teeth,causing decay.细菌附着在牙缝中的食物残渣上,导致蛀牙。
adj.随机的;任意的;n.偶然的(或随便的)行动
  • The list is arranged in a random order.名单排列不分先后。
  • On random inspection the meat was found to be bad.经抽查,发现肉变质了。
n.眼镜;斑点,微粒,污点( speck的名词复数 )
  • Minutes later Brown spotted two specks in the ocean. 几分钟后布朗发现海洋中有两个小点。 来自英汉非文学 - 百科语料821
  • Do you ever seem to see specks in front of your eyes? 你眼睛前面曾似乎看见过小点吗? 来自辞典例句
学英语单词
2-Acetyl-3-methylpyrazine
acclamations
acoustic weapon
ad dayr
Add to Template
allow for sth
Amarume
amnion cavity
arudies
assael
asset markets
automatic headers
baaprine
batched telecommunication
bedrid
bivial
bolt end
bring them down
calling-on signal
catalyst carrier
certificate of foreign exchange settlement for export
Chiba Bank,Ltd.
column ozone
conical reamer
cottis
crustiness
cuckoo-pint
dc-area
debt-service coverage ratio
dedicate one's life to...
diplodia maculans miyake et hara
ditransitive verb
double-action hammer
double-barrelleds
drifting force
eccentric balance weight
encoder/decoder
explanatory legend
EXQ
external contacting brake
face colorable plane
Fangahina Atoll
fenarol
flight test area
freireich
general most favoured nation clause
glauberitum
goods in foreign countries
group identifier
Hafursfjördhur
hbcag
hemitropous
high value standard resistor
Iapetic
industry discount
interrupt routine
Islamic law
lavelle
medium wave transmitter
medulla externa
modulation frequency feedback
moffroid
no-load discharge
occipital segment
oscillator synchronization
overcentralises
Penllyn
pilot well
place under probation
postparadensa
power transmission capacity of power line
projection functor
raskol
reading direction
readvised
rheumatics
Salvia hupehensis
satar communication
satellite dropping
sayfe
scarlet runner
schizopora flavipora
school board
semi-tracked vehicle
show a leg
snap-on ammeter
square mesh screen
standard income statement
sterol ester
sub spe rati
substandard sea water
swong
taperd ball end mill
third trimester
through passenger flow
titanolivinte
track receiving coil
ultra-dry bulb hygrometer
unify thread
user specification
uterine vulsellun forceps
Villa San Pietro