planet、star、asteroid有什么区别 啊？
The Eight Planets
Mike Brown
On August 24th 2006 the word "planet" was given its first-ever scientific definition by a vote of the International Astronomical Union. With the raising of a few yellow cards in Prague Pluto was demoted from full-fledged planet to "dwarf planet." The object 2003 UB313, sometimes called Xena, sometimes called the "10th planet," which in many ways precipitated this final debate, becomes the largest known dwarf planet. Unless astronomers revisit this issue at some point in the future, it is unlikely that there will ever be more than eight planets.
What was the problem with nine (or ten) planets?
Pluto and 2003 UB313 are significantly smaller than the other planets. If you were to start to classify things in the solar system from scratch, with no preconceived notions about which things belong in which categories, you would likely come to only one conclusion. The four giant planets -- Jupiter, Saturn, Uranus, Neptune -- belong in one category, the four terrestrial planets -- Mercury, Venus, Earth, Mars -- belong in one category, and everything else belongs in one or maybe more categories. You wouldn't lump the largest asteroid -- Ceres -- in with the planets, you would group it with the other asteroids. Likewise you wouldn't group the largest object in the vast swarm of objects beyond Neptune (the "Kuiper belt") with anything other than the Kuiper belt. The previous nine (or ten) "planets" encompassed the group of giant planets and the group of terrestrial planets and then awkwardly ventured out into the Kuiper belt to take in one or two of the largest of those objects. Using the word in this way makes no scientific sense whatsoever.
Two solutions to the problem of Pluto and 2003 UB313
Leave no iceball behind
Astronomers were faced with two options for a scientific definition of the word planet. One option was to say that what makes a planet a planet is simply the fact that it is large, round, and orbits a star. Ignore everything else that you know and concentrate on that. Why round? If you place a boulder in space it will just stay whatever irregular shape it is. If you add more boulders to it you can still have an irregular pile. But if you add enough boulders to the pile they will eventually pull themselves into a round shape. This transition from irregularly shaped to round objects is important in the solar system, and, in some ways, marks the transition from an object without and with interesting geological and planetary processes occuring (there are many many other transitions that are equally important, however, a fact that tends to be ignored in these discussions).
Of course, to truly talk only about the object in isolation and to ignore everything else you know you should also ignore the fact that the object is in orbit around another planet. It is hard to make a consistent argument that a 400-km iceball should count as a planet because it might have interesting geology, while a 5000-km satellite with a massive atmosphere, methane lakes, and dramatic storms (Titan) shouldn't be put into the same category, whatever you call it. For most people, considering round satellites (including our Moon) "planets" violates the idea of what a planet is.
The other difficulty with this definition is that it instantly makes 50 planets in the solar system with the likelihood of hundreds coming soon. Such a huge change in the number of planets is a big hint that this definition is a huge change in what we commonly think the word "planet" means. While most astronomers would agree that round vs. non-round is an important distinction in the solar system, most appear to feel that forcing the word "planet" to be the word that describes this transition is incorrect. This radical re-definition was initially proposed by the IAU but was met by heated opposition and had to be dropped.
Consider the circumstances
The other scientific definition that makes sense is to acknowledge that by any classification scheme that considers circumstances -- where the object is, what else is in orbit near by, whether an object is a satellite -- the first eight planets are clearly in a class of their own. There are many ways to attempt to state this definition: a planet is by far the dominant mass in its region of space, a planet has cleared its neighborhood of all other significant masses, a planet is the accumulation of most of the material in its orbital vicinity. While none of these definitions can be stated with rigorous precision, they are precise enough for the case of the Solar System where the division between objects with have and have not mostly cleared their regions of space is enormous.
One of the best ways to view this definition is to consider some of the distinct regions of space. The asteroid belt, for example, is a collection of small rocky bodies between Mars and Jupiter with many millions of members. The largest asteroid Ceres is not nearly massive enough to have accumulated all of the other asteroids, nor is it massive enough to shove the asteroids out of the solar system. It is not a dominant mass within the asteroid belt. The exact same could be said of Pluto and 2003 UB313 (which are essentially the same size and both in the Kuiper belt along with millions of other bodies). Every one of the eight planets easily passes this test though. The eight planets were created from an accumulation of most of the material that remained in their vicinity. They are the dominant bodies in their regions of space.
http://www.gps.caltech.edu/~mbrown/eightplanets/更多在这里 你自己筛选下
meteor 和 shooting star 区别为：意思不同、用法不同、侧重点不同。
一、意思不同
1、meteor：流星；大气现象abbr.气象学
2、shooting star ：飞驰的星星
二、用法不同
1、meteor ：Ameteor suddenly shot across the sky.一颗流星急速掠过天空。
2、shooting star ：So when a magical night sinks over the town and a shooting star flies across the sky, Maria wishes for a miracle.于是，当神奇的夜幕笼罩了城市，一颗流星划过天空，玛利亚祈祷出现奇迹。
三、侧重点不同
1、meteor ：是天文学中术语。
2、 shooting star ：是习惯的口语话的表示
行星（如地球、金星、土星、木星、海王星等）和小行星（如谷神星，就是比行星小得多的，而且也绕着恒星转，与行星类似，只是相对于其他行星很小而已）绕着恒星（如太阳）旋转
这样就构成了一个星系galaxy （如太阳系solar system）
PS：当然还有绕着行星旋转的卫星satellite（如月球）
planet 指行星，多译为星球；star是星星、恒星；asteroid是小行星。
planet 行星；星相
star （N.）星；明星；星级；星象（V.）标星号；点缀....
asteroid (n.)小行星；海盘车；海星； （adj.）形状的
eprtespnwa lapen 组合成单词,并写意思。
ANE, ANT, APE, APP, APT, ARE, ARS, ART, ASP, ATE, AWE, AWN, EAR, EAT, ENS, ERA, ERE, ERN, ERS, ETA, EWE, NAE, NAP, NAW, NEE, NET, NEW, PAN, PAP, PAR, PAS, PAT, PAW, PEA, PEE, PEN, PEP, PER, PES, PET.lapen 组合成单词:5 letter word(s):PANEL, PE...
求植物介绍(英文)的啊
韭莲---rainflower蛇鞭菊---gayfeather,blazing star欧洲银莲花---poppy anemone,windflower姜花---garland flower,white ginger lily紫藤---Chinese wisteria樱花---oriental cherry,flowering cherry葛藤---kudzu蛇莓---mock strawberry海棠---Chinese flowering crab apple迎春花---winter jasmine,forsythia紫薇---crape...