地球卫星英语

Satellite是一个英语单词，名词，作名词时意为“卫星；人造卫星；随从；卫星国家。卫星是环绕一颗行星按闭合轨道做周期性运行的天体。不过，如果两个天体质量相当，它们所形成的系统一般称为双行星系统，而不是一颗行星和一颗天然卫星。通常，两个天体的质量中心都处于行星之内。因此，有天文学家认为冥王星与冥卫一应该归类为双行星，但2005年发现两颗新的冥卫，又使问题复杂起来。月球就是最明显的天然卫星的例子。在太阳系里，除水星和金星外，其他行星都有天然卫星。太阳系已知的天然卫星总数（包括构成行星环的较大的碎块）至少有160颗。天然卫星是指环绕行星运转的星球，而行星又环绕着恒星运转。就比如在太阳系中，太阳是恒星，我们地球及其它行星环绕太阳运转，月亮、土卫一、天卫一等星球则环绕着我们地球及其它行星运转，这些星球就叫做行星的天然卫星。土星的天然卫星最多，已知82颗。木星的天然卫星第二多，已知79个。天然卫星的大小不一，彼此差别很大。其中一些直径只有几千米大，例如，火星的两个小月亮，还有木星，土星，天王星外围的一些小卫星。还有几个却比水星还大，例如，土卫六、木卫三和木卫四，它们的直径都超过5200千米。

人造卫星；卫星；卫星城；卫星国；外围组织

satellite卫星卫星 [ wèi xīng ] 生词本基本释义 详细释义[ wèi xīng ]围绕行星运行的天体。卫星本身不发光，因表面反射太阳光而发亮。分天然卫星和人造卫星。月球是地球的卫星。太阳系中除水星和金星外，其他行星都有数目不等的卫星。

单词是月亮的意思，它的音标是:/muːn /中文的谐音读法是:目恩

moon读作/mun/，意思是月亮。月亮是地球的卫星，它始终围绕着地球旋转。它自身不会发光，明亮的月光是月球反射太阳光的结果。在太阳系中，有好几颗行星都有自己的“卫士”，而且有些行星不止一个“卫士”。有一些较大的小行星也有自己的“卫士”，它们统称为卫星。卫星自身不会发光，但是和恒星不同，肉眼看上去，卫星的相对位置和行星一样，是会移动的。许多卫星和行星很相似，它们的运动轨道具有共面性、近圆性、同向性，并且与它们守卫的行星的距离按一定的规律分布着，这样的卫星称为规则卫星。反之，不具有这些性质的卫星，称为不规则卫星。卫星绕行星转动有两种方式：一种是和行星绕太阳转动的方向一致，称为顺行；一种是和行星绕太阳转动的方向相反，称为逆行。除了公转以外，卫星本身还有自转。研究发现，在浩大的太阳系中，除水星和金星之外，其他行星都有自己的天然卫星。目前太阳系已知的天然卫星总数至少有160颗，其中包括构成行星环的较大的碎块。天然卫星的大小不一，彼此差别很大。其中一些直径只有几千米大，例如，火星有两个小月亮，还有木星、土星、天王星外围的一些小卫星。还有几个在太空运行的卫星却比水星还大，例如，土卫一、木卫三和木卫四，它们的直径都超过5200千米。希望我能帮助你解疑释惑。

A communications satellite is a radio relay station in orbit above the earth that receives, amplifies, and redirects analog and digital signals carried on a specific radio frequency.In addition to communications satellites, there are other types of satellites:Weather satellites: These satellites provide meteorologists with scientific data to predict weather conditions and are equipped with advanced instruments Earth observation satellites: These satellites allow scientists to gather valuable data about the earth's ecosystem Navigation satellites: Using GPS technology these satellites are able to provide a person's exact location on Earth to within a few meters What are the different kinds of orbits?An orbit is the path that a satellite follows as it revolves around Earth. In terms of commercial satellites, there are three main categories of orbits:Geosynchronous Orbit (GEO): 35,786 km above the earth Orbiting at the height of 22,282 miles above the equator (35,786 km), the satellite travels in the same direction and at the same speed as the Earth's rotation on its axis, taking 24 hours to complete a full trip around the globe. Thus, as long as a satellite is positioned over the equator in an assigned orbital location, it will appear to be "stationary" with respect to a specific location on the Earth. A single geostationary satellite can view approximately one third of the Earth's surface. If three satellites are placed at the proper longitude, the height of this orbit allows almost all of the Earth's surface to be covered by the satellites. Medium Earth Orbit (MEO): 8,000-20,000 km above the earth These orbits are primarily reserved for communications satellites that cover the North and South Pole Unlike the circular orbit of the geostationary satellites, MEO's are placed in an elliptical (oval-shaped) orbit Low Earth Orbit (LEO): 500-2,000 km above the earth These orbits are much closer to the Earth, requiring satellites to travel at a very high speed in order to avoid being pulled out of orbit by Earth's gravity At LEO, a satellite can circle the Earth in approximately one and a half hours GEO vs. MEO vs. LEOMost communications satellites in use today for commercial purposes are placed in the geostationary orbit, because of the following advantages:One satellite can cover almost 1/3 of Earth's surface, offering a reach far more extensive than what any terrestrial network can achieve Communications require the use of fixed antennas. Since geosynchronous satellites remain stationary over the same orbital location, users can point their satellite dishes in the right direction, without costly tracking activities, making communications reliable and secure GEO satellites are proven, reliable and secure - with a lifespan of 10-15 years For a more comprehensive understanding of satellite advantages, see benefits of satellite.Satellite ArchitectureCommunications data passes through a satellite using a signal path known as a transponder. Typically satellites have between 24 and 72 transponders. A single transponder is capable of handling up to 155 million bits of information per second. With this immense capacity, today's communication satellites are an ideal medium for transmitting and receiving almost any kind of content - from simple voice or data to the most complex and bandwidth-intensive video, audio and Internet content.Diagrammatic Representation of a Satellite Orbital Location and FootprintThe location of a geostationary satellite is referred to as its orbital location. International satellites are normally measured in terms of longitudinal degrees East (° E) from the Prime Meridian of 0° (for example, Intelsat's IS-805 satellite is currently located at 304.5° E).The geographic area of the Earth's surface over which a satellite can transmit to, or receive from, is called the satellite's "footprint." The footprint can be tailored to include beams with different frequencies and power levels.Frequency Bands and BeamsSatellites transmit information within radio frequency bands. The frequency bands most used by satellite communications companies are called C-band and the higher Ku-band. Over the next several years, the use of a higher frequency band known as Ka-band is expected to increase. Modern satellites are designed to focus on different ranges of frequency bands and different power levels at particular geographic areas. These focus areas are called beams. Intelsat offers four beam types:Global: covering almost 1/3 of Earth's surface Hemi: covering almost 1/6 of Earth's surface Zone: covering a large landmass area Spot: covering a specific geographic area What is installed on the ground?All communications with a geostationary satellite require using an earth station or antenna. Earth Stations may be either fixed (installed at a specific location) or mobile for uses such as Satellite News Gathering (SNG) or maritime applications. Antennas range in size, from large telecommunications carrier dishes of 4.5 to 15 meters in diameter, to VSAT antennas which can be as small as under one meter, designed to support services such as Direct to Home TV (DTH) and rural telephony.The antenna, itself, will generally be connected to equipment indoors called an indoor unit (IDU), which then connects either to the actual communications devices being used, to a Local Area Network (LAN), or to additional terrestrial network infrastructure.Network TopologiesDepending on the application, satellites can be used with different ground network designs or network topologies. At its simplest, satellite can support one-direction or two-direction links between two earth stations (called respectively simplex transmission and duplex transmission). More complex communications needs can also be addressed with more sophisticated network topologies, such as star and mesh.The following examples show some of the options available to customers for configuring their satellite networks:Simplex Transmission Applications for simplex services include broadcast transmissions such as:TV and video services Radio services Point-to-Point Duplex Transmission Applications for duplex services include:Voice Telephony transport Data and IP transport (especially in asymmetric configurations) Corporate networks TV and Broadcast program contribution and distribution Point-to-Multipoint Transmission (May be simplex or duplex, symmetric or asymmetric).Applications for point-to-multipoint services include:Corporate networks, including VSAT services and business television Video and broadcast distribution, including Direct-to-Home Internet services Mobile Antenna Service Applications for mobile antenna services include:Satellite News Gathering Special Event Backhaul and Broadcasting Maritime services Star Network Applications for Star Networks include:Corporate Networks Distance Learning Mesh Network Applications for Mesh Networks include:National and International Telephony and Data networks Rural Telephony ---------------------------第二篇Not so long ago, satellites were exotic, top-secret devices. They were used primarily in a military capacity, for activities such as navigation and espionage. Now they are an essential part of our daily lives. We see and recognize their use in weather reports, television transmission by DIRECTV and the DISH Network, and everyday telephone calls. In many other instances, satellites play a background role that escapes our notice: Some newspapers and magazines are more timely because they transmit their text and images to multiple printing sites via satellite to speed local distribution. Before sending signals down the wire into our houses, cable television depends on satellites to distribute its transmissions. The most reliable taxi and limousine drivers are sometimes using the satellite-based Global Positioning System (GPS) to take us to the proper destination.The goods we buy often reach distributors and retailers more efficiently and safely because trucking firms track the progress of their vehicles with the same GPS. Sometimes firms will even tell their drivers that they are driving too fast. Emergency radio beacons from downed aircraft and distressed ships may reach search-and-rescue teams when satellites relay the signal (read this page for details).In this article, we will show you how satellites operate and what they do. You'll get to see what's inside a satellite, explore the different kinds of orbits and find out why the intended use of the satellite affects the choice of orbit. We'll even tell you how to see and track a satellite 希望能帮到你