英语听力:探索发现

Heset out to investigate a hundred-year-old theory that said asteroids werepowered by the Sun itself. It was called the Yarkovsky effect. The Yarkovskyeffect is a very small acceleration and acts on asteroids and what it is is ifyou take a model, the

发表于:2019-01-23 / 阅读(92) / 评论(0) 分类 探索与发现2014年

Weknew from the radar measurements where Golevka was within a few tens of metres.And yet it was actually 12 or 15 kilometres away from where it was predicted tobe without Yarkovsky effect. So these very precise radar observations allowedus to see the

发表于:2019-01-23 / 阅读(79) / 评论(0) 分类 探索与发现2014年

But there is a downside to Jupiter. It can also deflect asteroids into orbits that cross the Earths path. The Chelyabinsk meteor appears to be one of these typical Earth-crossing events. The likelihood is that it was thrown out of its regular orbit b

发表于:2019-01-23 / 阅读(85) / 评论(0) 分类 探索与发现2014年

On 6th October 2008, asteroid hunter Richard Kowalski saw something that would change the assessment of threats presented by asteroid impacts. The night was proceeding normally and up on the screen came another asteroid. As I continued to make observ

发表于:2019-01-23 / 阅读(63) / 评论(0) 分类 探索与发现2014年

Tim has developed a map to visualize their location. And on that map, the most important are the Near-Earth asteroids, the ones closest to the planet. On the screen here is a map of the solar system. And Ive got the Sun in the centre and the third pl

发表于:2019-01-23 / 阅读(97) / 评论(0) 分类 探索与发现2014年

Luckily, the very biggest asteroids are few and far between. But there are still plenty of rocks out there that represent a significant danger to us. So, at the summit of an extinct Hawaiian volcano, Professor Nick Kaiser and his colleagues are searc

发表于:2019-01-23 / 阅读(75) / 评论(0) 分类 探索与发现2014年

The meteorite was 15 kilometres across, enough to cause utter devastation across the whole planet. It exploded with a force of 100 million million tones of TNT. The blast sent a giant plume of vaporized rock out into space. A crater was punched 30 ki

发表于:2019-01-23 / 阅读(105) / 评论(0) 分类 探索与发现2014年

As the divers have explored further, they discovered the Siluteis are actually part of a huge complex of tounels and caves.In fact, when you look from above, you can see Senluties scattered across hundreds of kilometers.And when they were mapped, it

发表于:2019-01-23 / 阅读(81) / 评论(0) 分类 探索与发现2014年

Look at the size of this! This is magnificent! That is beautiful. This cave may be stunning, but it provides the evidence for one of the greatest catastrophes in the Earths history. And that water, its so clear! Lower the gear, please! Theres actuall

发表于:2019-01-23 / 阅读(59) / 评论(0) 分类 探索与发现2014年

Oh, perfect, perfect, perfect. Now were seeing the fireball come in, its brighter than the Sun and then, Kapow, it hits the surface. Jeez! This whole region, downrange, would have been incinerated. It would have been incinerated just by this plasma,

发表于:2019-01-23 / 阅读(87) / 评论(0) 分类 探索与发现2014年

So this was serial number one. It was built during the Apollo time. I guess because they thought there would be several of them made, but this is the first one and the last one and is the only one like it in the world. This is NASAs Vertical Gun Rang

发表于:2019-01-23 / 阅读(60) / 评论(0) 分类 探索与发现2014年

Down on the ground, the scale of impact is even more breathtaking.The crater is more than 1000 meters across and nearly 200 meters deep.The forces here were enoumous.The impact on this solid rock into this pulverized mochi,just bustled in your hand.Y

发表于:2019-01-23 / 阅读(106) / 评论(0) 分类 探索与发现2014年

Really, its a balance between the size of the object, its speed into the atmosphere and critically the altitude at which it explodes. Too high, if its too small and it explodes too high, the shockwave has little effect on the ground. If its quite low

发表于:2019-01-23 / 阅读(74) / 评论(0) 分类 探索与发现2014年

Most of the damage from an explosion like this is actually the blast wave. Its the very high winds. Mark created a simulation to see what size an asteroid would need to be to be able to generate such destructive power. In this simulation I include mo

发表于:2019-01-23 / 阅读(90) / 评论(0) 分类 探索与发现2014年

On June 30th, 1908, a huge explosion tore through the forest of Tunguska, Siberia. It was 20 years before the Russians mounted an expedition to the site. What they found astonished them. 60 million trees across an area the size of London had been lev

发表于:2019-01-23 / 阅读(93) / 评论(0) 分类 探索与发现2014年

So was this a near miss for us? If the asteroid had been in a different part of its orbit, so it didnt hit this year but it hit next year, it would have still hit us on February 15th. But instead of coming in over Russia, it would have come in over t

发表于:2019-01-23 / 阅读(84) / 评论(0) 分类 探索与发现2014年

There it is! Yep. Its about 90 kilometres up, at that stage, travelling at 17.5 kilometres per second. Using the different camera positions, scientists have pinpointed the exact position at which the meteor entered the atmosphere. And by tracking the

发表于:2019-01-23 / 阅读(71) / 评论(0) 分类 探索与发现2014年

Comparing the effects of an airburst with a ground strike, it seems the Chelyabinsk got away lightly. Its estimated that the largest piece to hit the ground weighed 500 kilos, a fraction of the asteroids original mass of 7,000 tonnes. Now if a piece

发表于:2019-01-23 / 阅读(87) / 评论(0) 分类 探索与发现2014年

An asteroid strike would create a huge explosion. NASA feared this might even be mistaken for a nuclear bomb. We wanted folks to know this was a natural event by Mother Nature rather than some sort of man-made event like a missile or something dreadf

发表于:2019-01-23 / 阅读(66) / 评论(0) 分类 探索与发现2014年

Approaching from beneath the planet, asteroid 2012 DA14 passed inside the orbit of our geostationary satellites before heading off to the north. This asteroid had been successfully tracked for a year. And despite its proximity, scientists knew that i

发表于:2019-01-23 / 阅读(73) / 评论(0) 分类 探索与发现2014年
学英语单词
achieva
adjustable swift
aeronautical station master log
amensa et thoro
Amphitryon 38
Arles salami
arnoglossus tenuis
assault-weapons
automatic circular knitter
be sb's poodle
BEF, B.E.F.
blotner
British Department of Energy
budgetary control plan
bugle players
business sense
calamondin orange
caplastometer
Chamberlain, (Arthur) Neville
chop logic
clauss
clutch release bearing spring
coistered
cooper shop
crude nickel sulphate
dimensions
Dollar duration
edeys
electromagnetogasdynamics
fibre reinforced plastic speed boat
filler weigher
fission energy
flat gain control
fly-tippers
Fortanete
FPQINA
French bracken
furrer
graticulated
high-wheeler
hinged molding box
hoza
hussy
hydraulic panel
image database
inertial navigator
italicism
keratiniz
kinderli b.
loan in trust
lumbosacral angle
lunching
mammiform
Mara, I.
meson dynamics
mimosa sensitivas
needle valve seat
no test link
no-float
nodal value
nonpressurized
Novgorodskaya Oblast'
once-shining
one-dimensional space
overflow page
paradise
pasty lubricant
port mcnicoll
power operation range
prevezas
Quebracho Coto
ratation of staff
rolling mill stand
screw spike
secondary liabilities
securities swapping
see sb right
selector repeater
shock bending test
side opposite the angle
side tone circuit
soft-headed hammer
soil mapping
spin effect
squamates
St. john's wort
strumpetly
tachykinesia
tailpipe augmentor
terminal cap
thicknesser
time slicing
topic of discussion
trits
udalman
vega real
volitient
Wadhurst
wood wool slab
World Exposition
yallop
you are a pig