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
-etin
adult migration
air chain
aircraft lease
all integer constraints
altar-cloths
Amsubit
antioxidant 1076
Apollo asteroid
archer fish tag
aretz
armed forces qualification test
attenuation of noise
beauces
big-party
binomials
biogas
break bulk ship
breeding property
brickowski
carrier sense network
Chavica
check byte
clock-towers
co-aunts
codability
code-sending radiosonde
compound probability
crenophilous
cumnors
cutaneous pseudolymphoma
D antiscorbutic factor
datacom
dock master
dwarf buckeye
electric radiant heating
electron bridge
endoscoping
enlisted
extracampine hallucination
falkiner
feeding bridge
felis yagouaroindi panamensis
fiber cement board
firearmed
floating piston pin (floating gudgeon pin)
frequency response of network
fused together
go banana
Goldstein's hematemesis
grain precleaner
gruesomenesses
hacksawing
hapful
heat of subcooling
hereditary neutropenia
high volume electric speaker
hilty
if-a-then-b gate
jocosenesses
kite flyer
Laga, Kep.
leucyl leucine
marcantel
mareschini
minimum turning diameter
moorit
nyxis
over-recording
overlocks
Para-dichlorobenzol
pear-switch
percentage of utility loss
pseudorange difference
ptychodont
pulse frequency diversity
Queanbeyan
red-hunter
region enclosed by a curve
remember me to
Ronchese test
Sciez
scyllarides haanii
segregation of gene
seok
sequential file organization
set of nonnegative integer
Sigd
single-beam travel crane
snake oil
Sulfapyrazinmethoxine
swill out
symbiotic nitrogen fixation rates
syncytotoxin
theory of punctiform sensation
Toften
tricoccous
twittered
verbal auditory ballucination
vertical dial
wood-borer
WR44923