关闭图标
log图标

toefl.viplgw.cn

  • 使用手机注册
  • 使用邮箱注册
  • 手机号不能为空!

    验证码不能为空!

    用户名不能为空!

    密码不能为空!

  • 邮箱不能为空!

    验证码不能为空!

    用户名不能为空!

    密码不能为空!

已有账号? 登录到雷哥托福
关闭图标
log图标
  • 使用手机找回密码
  • 使用邮箱找回密码
  • 手机号不能为空!

    验证码不能为空!

    密码不能为空!

  • 邮箱不能为空!

    验证码不能为空!

    密码不能为空!

又想起来了
加入生词本

listen

英['lɪs(ə)n] 美['lɪsn]
vi. 听,倾听;听从,听信
n. 听,倾听

已添加
×

我要举报草莓小菇凉评论

用户头像
草莓小菇凉:说的非常好,十分有道理,棒棒棒!

06-08 15:44:55

请选择举报类型:

举报电话:400 1816 180    举报QQ:2095453331
×
logo图标
分享到雷哥托福

分享成功图标分享成功

邀请名师点评成功,管理员正在安排老师进行点评。

继续做题 返回首页
支付雷豆失败图标 雷豆余额不足 购买雷豆 返回
报告题目错误
请选择错误类型:
请描述一下这个错误:

取消

文章结构

Official 19-L2 .Difficulties in Astronomy 点击收藏

标准

  • 高音
  • 静音
  • 句子
    精听
  • 全文
    精听
  • 听写
    模式
  • 点击查看本句

    听写本句 再播一遍 下一句
  • 点击查看全文

    再播一遍本文

    Listen to part of a lecture in an astronomy class.

    So how many of you have seen the Milky Way, the Milky Way galaxy in the sky?

    You? You have?

    Yeah, I was camping, and there was no Moon that night, it was super dark.

    Um anybody else? Um...not too many.

    Isn't that strange that the Milky Way is the galaxy that the planet Earth is in, and most of us have never seen it?

    Now, what's the problem here.

    Light pollution, right? From street lights and stuff.

    Yes, especially unshielded street lights, you know, ones that aren't pointed downward.

    Now, here is an irony, the building we are in now, the astronomy building not far from our observatory has unshielded lights.

    So the problem is pretty widespread.

    It's basically beyond control, as far as expecting to view the night sky anywhere near city, I mean.

    Um, I've live around here my whole life, and I 've never seen that Milky Way within city limits, and I probably never will.

    There is a price for progress, uh?

    But let's think beyond light pollution.

    That's only one kind of a technological advance that interfered with the astronomical research.

    Can anyone think of another?

    No, OK. Let's look at it this way.

    We don't only gain information by looking at the stars.

    For the past seven years or so, we've also used radio astronomy, which lets us study radio waves from the sky.

    How can you observe radio waves, I mean tell anything about the stars from that.

    Well, in optical astronomy, using a telescope and observing the stars that way,

    we rely on visible light waves. What we are seeing from Earth is actually electromagnetic radiation that's coming from stars, and just one part of it is visible light.

    But there are problems with that.

    When photons and light waves hit objects in our atmosphere, water droplets oxygen and nitrogen molecules, dust particles and so on, these objects are illuminated, they are lit up, and those things are also being lit by all our street lights, by the Moon, all these ambient light.

    And on top of that, when that visible radiation bounces off those molecules, it scatters in all directions.

    And well, lights from stars, even nearby in our own galaxy, doesn't stand a chance against that.

    Basically, the light bouncing off all these objects close to Earth is brighter than what's coming from the stars.

    Now, radio waves are electromagnetic radiation that we can't see.

    Nearly all astronomical objects in space emit radio waves, whether nearby stars, objects in far away galaxies, they all give off radio waves.

    And unlike visible light waves, these radio waves can get through the various gases and dust in space, and through our own Earth's atmosphere comparatively easily.

    Ok, then we might as well give up on optical astronomy and go with radio astronomy.

    Well, the thing is, with a radio astronomy, you can't just set up a telescope in your backyard and observe stars.

    One problem is that radio waves from these far away objects, even though they can get through, are extremely faint.

    So we need to use radio telescopes, specially designed to receive these waves.

    And then, well, we can use computers to create pictures based on the information we receive.

    That sounds cool, so how do they do that?

    Well, it's kind of like the same way a satellite dish receives its signal, if you are familiar with that.

    But radio telescopes are sometimes grouped together, is the same effect as having one really big telescope to increase radio wave gathering power.

    And they use electronics, quite sophisticated.

    Yeah, it's neat how they do it, but for now, why don't we just stick with what we can learn from it.

    Em, some very important discoveries have been made by this technology, especially you consider that some objects in space give off radio waves but don't emit any light.

    We have trouble discovering those sorts of bodies as much as studying them using just optical telescopes.

    Well, if the radio waves are so good at getting through the universe, what's the problem?

    Well, answer this, how come people have to turn off their cell phones and all our electronic devices when an air plane is about to take off?

    The phones interfere with the radio communication at the airport, right?

    Oh, so our radio waves here, on Earth interfere with the waves from space?

    Yes, signal from radios, cell phones, TV stations, remote controls, you name it, all these things cause interference.

    We don't think about that as often as we think about light pollution.

    But all those electrical gadgets pollute the skies, just in a different way.

    • special
    ☞查看答案 再播一遍

联系雷哥托福

全国免费咨询热线:400 1816 180

  • 上海(总部)
  • 北京
  • 成都
  • 杭州
  • 武汉
  • 南京
  • 广州
  • 西安
  • 重庆
  • 深圳
  • 上海(总部)服务中心

    电话:400 1816 180

    地址:上海市徐汇区文定路218号德必徐家汇WE艺术湾B座205

    公交路线:76路、93路、138路宜山路蒲汇塘路站;205路、732路、754路南丹路宜山路站;205路、754路、830路南丹路文定路站等

    地铁路线:地铁3号线、4号线宜山路站出站470m;地铁1号线、4号线上海体育馆站出站600m。

  • 北京服务中心

    电话:400 1816 180

    地址:北京市朝阳区雅宝路7号 E园EPARK大厦508

    公交路线:乘坐公交44路外环;58路;139路;特12路外环;特2路;夜20路外环到雅宝路公交站 下车,走140米即可达到。

    地铁路线:乘坐地铁1号线、2号线到建国门站(A出口)步行1000米即可到达;乘坐地铁2号线、6号线到朝阳门站(A出口)步行1200米即可到达雅宝路7号 E园EPARK大厦。

  • 成都服务中心

    电话:400 1816 180

    地址:成都市锦江区总府路31号Z31六楼(皇冠假日酒店旁)

    公交路线:乘坐58路、98路、锦城观光3号线、熊猫快线5号线在春熙路步行街北站下 步行约281米。

    地铁路线:乘坐地铁2号线或者3号线到春熙路C口下,步行约982米

  • 杭州服务中心

    电话:400 1816 180

    地址:杭州市江干区江锦路159号 平安金融中心B座8楼

    公交路线:901路、105路环线、106路环线、9M路:富春路民心路口站 176路:市民中心北大门站,市民中心西大门站

    地铁路线:号线钱江路站;4号线钱江路,江锦路

  • 武汉服务中心

    电话:400 1816 180

    地址:武汉市珞瑜路光谷世界城广场写字楼1栋1单元14层11421室

    公交路线:乘坐18路,25路,340路,510路,518路,521路等公交车到珞瑜路湖北省中医院站下车

    地铁路线:乘坐地铁2号线至珞雄路A口出,往湖北省中医院光谷院区方向步行50米至世界城广场写字楼

  • 南京服务中心

    电话:400 1816 180

    地址: 南京市秦淮区中山东路532号金蝶科技园 H1幢308号(林客社 内)

    公交路线:5路 34路 34路区间 36路 55路 59路 y5路夜间 17路 65路 115路 118路 y17路夜间

    地铁路线:地铁2号线明故宫站1号口出,向东200米

  • 广州服务中心

    电话:400 1816 180

    地址:广州市天河区体育西路103号维多利广场B座26楼K15

    公交路线:11,18,20,230,278,293,45,583,669,886冼村路中站下。 194,40,777,778,90,观光2路花城广场路站下。

    地铁路线:乘坐地铁APM线至花城大道站下B口出,步行约500米即可到达保利威座大厦北塔。

  • 西安服务中心

    电话:400 1816 180

    地址:西安市莲湖区北大街西华门十字西南角78号嘉会广场C座4层B021号

    公交路线:4路、12路、26路、36路、37路、229路、游7钟楼北站;15路、16路、32路、102路、182路、236路、286路西华门站。

    地铁路线:地铁二号线钟楼站150米;地铁一号线/二号线北大街站700米。

  • 重庆服务中心

    电话:400 1816 180

    地址:重庆市渝中区邹容路68号大都会广场16楼1603-1604室

    公交路线:401、135、114、111、401、151、862、181、262、105、866、153、466

    地铁路线:2号线临江门站500米、1号线小什字站500米、6号线小什字站500米。

  • 深圳服务中心

    电话:400 1816 180

    地址:深圳市罗湖区书城路都市名园B栋5楼B区(只接受预约拜访)

    公交路线:101路 10路 12路 203路 214路 215路 223路 29路 3路 85路 M112路 M191路 M192路 N3路 P100路(定制公交请预约) 高快巴士200号线 高快巴士20路 高快巴士863号线到地王大厦下,步行431米即可到达。

    地铁路线:乘坐1号线/罗宝线/2号线/蛇口线到大剧院(E口)出,步行498米即可到达都市名园B栋

预约托福考试规划师