常见话题
- 地球，月球，太阳系
- 恒星、行星、小行星、彗星、流星、陨石
- 星座、星云、银河系
- 天文学力量（heliocentric theory 日心说，geocentric theory 地心说）
- 其他：月球的陨石坑，火星表面的税，彗星运行的轨道等
词汇积累
- universe 宇宙
- plasma 等离子体: a gaseous soup of charged particles. a moving electric charge generates a magnetic field.
- sun spot
- astronomical 天文的
- space 空间
- cosmos 宇宙
- stellar 恒星的
- vacuum 真空
- cluster of galaxies 星系团
- galaxy 星系
- asterism 星群
- constellation 星座
- big dipper 北斗七星
- solar system
- planet 行星
- moon 月球，卫星
- comet 彗星, Comets are “dirty snowballs”, composed of dust and ice
- constellation 星座
- debris 残骸，碎片
- collide 碰撞，冲突conflict
- big dipper（🥄） 北斗七星
- constellation 星座
- geyser: a hole in the ground from which hot water and steam come out
- draw into 吸入
- star 恒星
- corona 日冕
- chromosphere 色球层
- photosphere 光球层
- eclipse 日蚀
- solar radiation 太阳辐射
- black hole 黑洞
- gravity 重力
- gravitation 引力
- singularity 奇点
- collapse 塌缩
- grave 坟墓，沉重的
宇宙中的基本物质
- gas
- dust
- water
- ice
Hydrogen
Helium
Nitrogen
Carbon 碳
Ammonia 氨
Ammonia is a colorless highly irritating gas with a sharp suffocating odor. It dissolves easily in water to form ammonium hydroxide solution which can cause irritation and burns. Ammonia gas is easily compressed and forms a clear, colorless liquid under pressure.
氨是无色气体，有强烈刺激气味，极易溶于水。常温常压下，1单位体积水可溶解700倍体积的氨。氨对地球上的生物相当重要，是所有食物和肥料的重要成分。氨也是很多药物和商业清洁用品直接或间接的组成部分，具有腐蚀性等危险性质。 由于氨有广泛的用途，成为世界上产量最多的无机化合物之一，约八成用于制作化肥。
Methane 甲烷
Methane is gas that is found in small quantities in the atmosphere. Methane is the simplest hydrocarbon, consisting of one carbon atom and four hydrogen atoms. Methane is a powerful greenhouse gas. Shown here are four representations chemists use for methane.
甲烷，是结构最简单的烃类，化学式为CH4，由一个碳原子以及四个氢原子组成。它是天然气的主要成分。甲烷在地球上有很高的相对丰度，使之成为很有发展潜力的一种燃料，但在标准状态下收集以及存储气态的甲烷是一个十分有挑战性的课题。在自然状态下，甲烷可以在地底下或者海底找到，大气中也含有甲烷，这些甲烷称为大气甲烷。
Iron 铁
Iron is a chemical element; it has the symbol Fe (from Latin ferrum ‘iron’) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, forming much of Earth’s outer and inner core. It is the fourth most abundant element in the Earth’s crust, being mainly deposited by meteorites in its metallic state.
铁，是一种化学元素，化学符号为Fe，原子序数为26，原子量为55.845 u，属于第一列过渡元素，位在周期表的第8族。依质量计，是在地球上是占比最多的元素，为地球外核和内核的主要成分。它也是地壳中含量第四多的元素。 地壳中的纯铁十分稀少，基本上只存在于陨石中。
Celestial Body 天体
- planet 行星
- Dwarf 矮星、侏儒（brown & white dwarf）
- Asteroid 小行星
- minor planet 小行星
- comet 彗星（有轨道）
- meteoroid 流星体
- meteor 流星（shooting star）
- meteorite 陨星
- exoplanets: extrasolar planets(太阳系以外的行星，主要寻找类似地球的环境), EXOPLANET is a planet orbiting a star that is not our sun.
- Star: hoststart 恒星或主星，其他行星围绕恒星旋转
- gas giants 外部行星（火星以外的）
- rocky planet 内部行星（水，金，地，火）
- proto-planets 原始星
Solar System 太阳系（八大行星）
- Mercury 水星
- Venus 金星
- Earth 地球
- Mars 火星
- Ceres 谷神星
- Asteroid belt 小行星带
- Jupiter 木星
- Saturn 土星
- Uranus 天王星
- Neptune 海王星
- Pluto 冥王星（刚开始在，后来被开除太阳系，因为太小了）
口诀: MVEMJSUN
Comet: 哈雷彗星 76周年(perodic orbits)
- 类地行星(Terrestrial planet): Mercury, Venus, Earth, Mars
- 类木行星(Jovian planet, Gas Giant): Jupiter, Saturn, Uranus, Neptune
Sun 太阳
Sun is star, powered by nuclear fusion in its core. Hot plasma moves inside the Sun, creating magnetic fields, which in turn can create sunspots, solar flares, and coronal mass ejections. These event can generate aurorae on Earth, causing power blackouts, and damage satellites.
- corona 日冕
- sun spot
- faculate
- tangled up 纠结
sunspots(太阳黑子；雀斑) (dark areas where the sun’s magnetic field reaches the surface) and solar storms (ejections of energy from the sun that reach into space and can affect Earth).
During a storm, energy explodes from the sun in the form of light and particles (called a solar flare) and a plasma and magnetic field (called a coronal mass ejection, or CME).
If a CME hits Earth’s magnetosphere, it can wreak havoc on our planet’s magnetic field, injecting energy, plasma and particles and heating up and distorting Earth’s upper atmosphere, the ionosphere. All of this chaos can hinder radio signals between satellites and induce strong electric currents that can damage power grids. On the plus side, we often get a nice view of the Northern and Southern Lights(北极光和南极光) as a surge of particles hits Earth’s atmosphere at the poles.
太阳黑子是太阳光球上的临时现象，它们在可见光下呈现比周围区域黑暗的斑点。它们是由高密度的磁性活动抑制了对流的激烈活动造成的，在表面形成温度降低的区域。虽然它们的温度仍然大约有3000-4500K，但是与周围5,780K的物质对比之下，使它们清楚的显视为黑点，因为黑体的热强度与温度的四次方成正比。
Sunspots are temporary spots on the Sun’s surface that are darker than the surrounding area. They are regions of reduced surface temperature caused by concentrations of magnetic flux that inhibit convection.
Solar faculae(太阳谱斑) are bright spots in the photosphere that form in the canyons between solar granules, short-lived convection cells several thousand kilometers across that constantly form and dissipate over timescales of several minutes.
A solar flare(太阳耀斑) is a relatively intense, localized emission of electromagnetic radiation in the Sun’s atmosphere. Flares occur in active regions and are often, but not always, accompanied by coronal mass ejections, solar particle events, and other eruptive solar phenomena. The occurrence of solar flares varies with the 11-year solar cycle.
A coronal mass ejection (CME) is a significant ejection of magnetic field and accompanying plasma mass from the Sun’s corona into the heliosphere. CMEs are often associated with solar flares and other forms of solar activity, but a broadly accepted theoretical understanding of these relationships has not been established.
Our light, our lives, everythin we do is controlled by the Sun, depends on it. It’s the great god helios driving his chariot across the sky, the egyptian god RA reborn every day. The summer solstice(至，至日；至点) rising at stonehenge(巨石阵) for millions of years.
This was as close as it got to staring into the face of god. It’s so far away, if it burned out we wouldn’t know about it for eight minutes. It’s so big you could fit one million earth inside it.
But who needs numbers, we’ve got the real thing, we see it every day a familar face in out sky, no up colse, it’s unrecognizable, the turbulent sea of incandescent(炽热的) gas. The thermometer pushes 10,000 degrees. Can’t imagine how hot the core is could be tens of millions of degrees.
Hot enough to transform millions of tons of matter into energy every second, more than all the energy ever made by mankind, dawarfing the power of all the nuclear weapons on earth, back home we use this energy for light, and heat, but up colse, there’s nothing comforting about the Sun.
It’s electrical and magnetic forces erupt in giant molten gas loops, some are larger than a dozen earths, more powerful than 10 million volcanoes. When they burst through they expose cooler layers below, making sunspots, a fraction cooler than their surroundings, sunspots look black but they’re hotter than anything on earth. And massive up to 20 times the size of earth.
But one day, all this will stop, the sun’s fuel will be spent, and when it dies the earth will follow. This god creates life, destroys it and demands we keep our distance.
Mercury 水星（离太阳最近，速度快）
no atmosphere, craters, hard to observe from Earth, elliptical orbit
large iron core. magnetic field, water ice in deep craters, hot
It must be Mercury, get too close to the Sun, this is what happens, temperatures swing wildly here at night it’s minus 275 degrees, come midday it’s 800 plus. Burnt then frozen. The messenger space probe is telling us something strange, for its size mercury has a powerful gravitational pull, it’s a huge ball of iron covered with a thin veneer of rock, the core of what was once a much large planet, so where the rest of it, maybe a stray planet slammed into mercury, blasting away its outer layers in a deadly game of cosmic pinball.
Whole worlds on the lose careening wildly across the cosmos destroying anything in their path and we’re in the middle of it.整个世界都在迷失中，在宇宙中疯狂地倾斜，摧毁了他们前进道路上的一切，而我们就在其中。
vulnerable exposed small everything is telling us to turn back, but who could defy this, the Sun in all its mesmerizing splendor.
Venus 金星 (the goddess of love, 启明星，最亮的太阳系行星，夜空中最亮的星)
The thirdest brightest natural object inthe sky after the Sun and Moon.
The best time to see it: after the sunset, before the sun rise.
The morning star, the evening star, she can welcome the new day in the east, say good night in the west.
- Transits: block the Sun.
- Cloud is so thick:
- 460 C
- acid rains S02, sulfur dioxide
- lacks of magnetic field.
- snow
- rotates slowly
- no moon
- most sphierical of all the planets
- greenhouse effect, hottest planet in the solar system
A sister to our planet, she’s about the same size and gravity as earth, we should be safe here, but the venus express space probe is setting off alarms, it’s telling us that these dazzling(眩目的) clouds they’re made of deadly sulfuric acid, the atmosphere is choking(塞满) with carbon dioxide.
Never expected this, Venus is one angry goddess, the air is noxious, the pressure unbearable, and it’s hot approaching 900 degrees, stick around and we’d we corroded, suffocated, crushed and baked(待在这里，我们就会被腐蚀，窒息，碾碎，烘烤).
Nothing can survive here, not even this soviet robotic probe, its heavy armor has been trashed by the extreme atmosphere. So lovely from earth up colse this goddess is hideous, she’s the sister from hell, pock marked by thousands of volcanoes, all that carbon dioxide is trapping the sun’s heat, venus is burning up its global warming gone wild, before it took hold maybe venus was beautiful, calm more like her sister palnet earth. So this could be earth’s future.
Earth 地球
- Crust 地壳
- mantle 地幔（中间层）
- core 内核
Mars 火星
The red planet, unmistakably mars, for centuries we’ve looked to mars for company, for signs of life, could there be extraterrestrial life here.
- god of war
- small and colder than Earth
- dry now
- Red(Rusty/iron)
- half the size of Earth
- clement （天气）温和的；（人、行为）仁慈的
- probes 探索；探针；试样（probe 的复数）
- dichotomy 两分；分裂；双歧分枝
- topography maps 地形图；等高线图
- Tharsis bulge 塔西斯高地隆起
- the largest volcanoe in the solar system: Olympus Mons
- grand 壮丽的;宏大的
- polar ice caps(帽子)
- dry ice(frozen carbon dioxide)
- water ice
- thin atmosphere
- heavily cratered
- avalanches 雪崩
- dislodge 逐出
- skylights 天窗
- shelter from solar radiation
- seal up 封闭
red and dead.
lava flow
Where there’s water, there could be life.
spearheaded v．领头，带头：在某个活动、运动或组织中担任领导角色。 harbored life 窝藏生命
勇气号火星探测器 (Spirit)
Martian Dust Devil
Jupiter(biggest, gas giant，木星)
- oblivion 遗忘
- fastest spin
- Largest planet in solar system
- gas giant
- brightest
- zones and belts: The lighter colored bands are called zones, and the darker colored bands are called belts. The belts have higher temperatures and are thus located lower in the atmosphere, closer to the heat generating core while the cooler zones are located higher in the atmosphere.
- Great red spot
- Liquid metalic hydrogen 液态金属氢
- Molecular hydrogen 分子氢
Jupiter’s Moons
- 67 moons confirmed
- Galilean moons
4 biggest monns(rock and ice):
- Ganymede: crator, may have an iron solid core, tides, oceans of water, salty liquid water
- Callisto: rocky core, createred, old,
- IO: volcanos(400+), tides, friction, magnetetic,
- Europa: under surface ocean(may have life)
Saturn 土星
Saturn is the sixth planet from the Sun, and the second largest in the solar system. It’s surrounded by beautiful rings.
土星，为太阳系八大行星之一，至太阳距离位于第六、体积则仅次于木星。并与木星同属气体巨行星。古代中国亦称之为镇星、填星。据说，古人观察镇星呈黄色，黄色于“五行”属土，而命名为土星。
Saturn is the sixth planet from the Sun and the second largest planet in our solar system. Adorned with a dazzling system of icy rings, Saturn is unique among the planets.
Saturn is a massive ball made mostly of hydrogen and helium. The farthest planet from Earth discovered by the unaided human eye, Saturn has been known since ancient times. The planet is named for the Roman god of agriculture and wealth, who was also the father of Jupiter.
Uranus & Neptune（天王星和海王星）
Uranus and Neptune are ice giants, with small rocky cores, thick mantles of ammonia, water, and methane, and atmospheres that make them look greeish and blue. Uranus has relatively dull weather, while Neptune has clouds and storms whipped(鞭子) by tremendous winds. Both have rings and moons, with Neptune’s Triton probably being a captured iceball that has active geology.
Uranus was the first planet to be discovered. It took an astronomer with a telescope to find it.
Uranus is called an ice giant.
Neptune is faint.
Aurora 极光（电磁现象）
太阳发射的电子颗粒(Sun spot activity)和地球磁场碰撞形成的，发出不同的光是因为各种不同的元素发生了电子越迁。（类似烟花，不同金属元素会释放不同的光芒）。
太阳的活动会影响地球的电磁类的技术和设备运行。(disruptions)。
flare-up: 爆发
Nebula 星云
A nebula is a giant cloud of dust and gas in space. There are three types of nebulas:
- emission nebula 发射星云(emiting light itself, red light)
- reflection nebula 反射星云(does not emit light, reflect light from surrounding nebula, blue light)
- Dark nebula 暗星云(so dense, block light)
Technologies 技术
- coronagraph 日冕仪(消弱其围绕的恒星发光的影响，使得其他发光微弱的星球能被看到。一种照相技术，成像)
- 望远镜 telescope
- spectroscopy 光谱学（利用物质发射、吸收或散射的光、声或粒子的现象，来研究物质或能量的方法。可以知道天体的温度，包含物质）
距离相关
距离发现顺序：earth’s circumference(without a telescope) -> AU -> solar systems distances -> galaxy
- Ancient Greeks finding the size of the Earth.
- Earth/Sun distance began our use of parallax
- Brightness relation to distance
- Knowing the circumferences, they were able to calculate the distances between Sun and Earth, Moon and Earth, as well as their sizes.
- AU(Astronomical Unit, 天文单位): the average distance between Earth and the Sun. foundamental
Parallax 视差
视差 (Parallax) the apparent displacement or the difference in apparent direction of an object as seen from two different points not on a straight line with the object.
视差是指从两个不同位置观察同一个物体时，此物体在视野中的位置变化与差异。从两个观察点看目标，两条视线之间的夹角叫做这两个点的视差角，两点之间的距离称作视差基线。 从同样的两个观察点看，目标物体距离越近就有越大的视差，因此视差可以被用来反向估算物体的距离。
Parsec 秒差距（距离单位）3.26光年
The parsec (symbol: pc) is a unit of length used to measure the large distances to astronomical objects outside the Solar System, approximately equal to 3.26 light-years or 206,265 astronomical units (AU), i.e. 30.9 trillion kilometres (19.2 trillion miles).
megaparsecs 百万秒差距
Light Year 光年
光年是长度单位之一，指光在真空中一年时间内传播的距离，大约为9.46兆公里。 光年一般用于天文学中，是用来量长度很长的距离的单位，如太阳系跟另一恒星的距离。
A light-year is the distance that light travels in a vacuum in one Julian year (365.25 days).
Light year(the distance the light traveled within one year)
AU(Astronomical unit 天文单位)
AU is the fundamental meterstick of astronomy, the scale we use to measure everything.
天文单位（英语：Astronomical unit，缩写的标准符号为AU，也写成au、a.u.或ua）是天文学上的长度单位，曾以地球与太阳的平均距离定义。 2012年8月，天文学家以无记名投票的方式，把天文单位固定为149,597,870,700米。
lifecycle of starts (恒星演变和死亡)
- Population II stars, the oldest stars, are formed from hydrogen and helium gases, and they shine until they exhaust their fusible material.
- Population I stars, including the Sun, are relatively young stars that are mostly hydrogen and helium gas but also contain heavier elements.
- The outer envelope of the Sun and stars like it will release their energy into space, and the inner cores will become white dwarfs before they finally give off their last energy.
Star(fusion reaction, hydrons collpased with each other emiting light) -> red giant star(inner fusion stopped, outer expaned and cooled) -> dwarf star(The core will shrink, giving off the last of its energy)
Is universe welcoming or hostile. 宇宙是欢迎还是敌对。
- malevolent dark forces 恶毒的黑暗势力
- star trek 星际迷航
- desolate 荒凉的
- barren 贫瘠的
- oddly familiar 感觉奇怪地熟悉：
Comet 彗星（扫把星，冰球，彗核是由松散的冰、尘埃和小岩石构成的, ice+rock, dirty snowballs）
Comets are chunks of rock and ice(dirty snowballs) that orbit the Sun, when they get near the Sun they trun into gas, forming the long tail, and also releases dust that forms a different tail.
Eons ago, comets(and asteroids) may have brought a lot of water to Earth as well as the ingredients for life.
Sublimation(升华): a process when ice turns into gas
- ice: frozen water,frozen carbon dioxide, frozen carbon monoxide, methane, ammonia
- gravel and dust 砾石和灰尘
- core: nucleus
- gas: coma(leaves a tail)
two types of tails:
- dust tail: white or teeny bit yellowish, reflect sunlight
- ion tail: blue or green, gas
by orbits:
- short-period comets
- long-term comets
Sungrazers: 掠日彗星
This comet strayed too close, the sun’s heat is boiling it away, creating a tail that stretches for millions of miles, it’s freezing it here, there no doubt where this comes from, the icy wastes of deep space, but all this steam geysers and dust(间歇泉和尘埃), it’s the sun again, melting the comet’s frozen heart, strange, a kind of vast dirty snowball, covered in grimy tar, tiny grains of what looks like organic material preserved on ice who knows when, maybe even the beginning of the solar system.
Say a comet like this crashed into the young earth billions of years ago. Maybe it delivered organic material and water. The raw ingredients of life, and may even have sown(播种；布满) the seeds of life on earth that evolved into you and me, but saved crashed into the earth, now think of the dinosaurs, wiped out by a comet or asteroid strike.
It’s only a question of time, eventually one day, we’ll go the way of dinosaurs. If life on earth was wiped out, we’d be stuck out here, homeless, adrift in a hostile universe, we need to find another home, among the millions billions of planets. There must be one that’t not too hot not too cold with air sunlight water. We’re like goldilocks we could comfortably live.
Astroids(star-like) 小行星
shooting stars 流星
Ceres(between Mars and Jupiter)
Carbon-based Silicon-based
Main Belt
Meteors(流星)
Light 光(电磁波，Electromagnetic Radiation)
Light is form of energy. Its wavelength tells us its energy and color. Spectroscopy allows us to analyze those colors and determin an object’s temperature, density, spin, motion, and chemical composition.
Electro magnetic radiation.
Energy goes up when the lightwaves is shorter.
Light radiates from a source in waves. Each wave has two parts; an electric part, and a magnetic part. That’s why light is called Electromagnetic Radiation.
Our brains interpret light waves by assigning different colors to the different wavelengths, but much of the light in the Universe travels with wavelengths too short or too long for the human eye to detect. The longest wavelengths are the infrared, microwave, and radio portions of the spectrum. The shortest wavelengths of the spectrum are the ultraviolet, x-ray, and gamma radiation. The visible portion is a very small part of the electromagnetic spectrum.
How is light made?
temperature: cooler objects give shorter wave length.
spectroscopy 光谱学
Different atoms emit different colors of light, if we can measure that light, in priciple we can determin that an object is made of, even if we can’t touch it.
Spectroscopy is the study of the absorption and emission of light and other radiation by matter. It involves the splitting of light (or more precisely electromagnetic radiation) into its constituent wavelengths (a spectrum), which is done in much the same way as a prism splits light into a rainbow of colours.
光谱学是利用物质发射、吸收或散射的光、声或粒子的现象，来研究物质或能量的方法。又称谱学，且因研究对象不同，而有不同名称，例如：能谱学、波谱学、频谱学、质谱学、介电谱学。 光谱学原始定义为研究光和物质之间相互作用的学科。历史上，光谱学是指：用“可见光”来对物质结构的理论研究、进而对物质定性定量分析的科学分支。
棱镜 (Prism)
By measuring the wave length shift, we can tell if an object is moving toward or awar from us.
The universe is expanding because of the red shift.
‘Red shift’ is a key concept for astronomers. The term can be understood literally - the wavelength of the light is stretched, so the light is seen as ‘shifted’ towards the red part of the spectrum. Something similar happens to sound waves when a source of sound moves relative to an observer.
We can determin if an object is spinning and how fast, whether it has a magnetic field, and even how massive and dense an object is.
Stars 恒星
- Hot stars are blue, yellow stars are red.
- Luminosity depends on size and temperature
- HR diagram(恒星光度和温度之间的关系图)
- Stars can be categorized using their spectra
- Spectra with distance can identify luminosity, size, and temperature
- The HR diagram plots luminosity vs temperature
- most stars fall along the main sequence
A spectrum is simply a chart or a graph that shows the intensity of light being emitted over a range of energies. Have you ever seen a spectrum before? Probably. Nature makes beautiful ones we call rainbows. Sunlight sent through raindrops is spread out to display its various colors (the different colors are just the way our eyes perceive radiation with slightly different energies).
https://imagine.gsfc.nasa.gov/science/toolbox/spectra1.html
Spectroscopy can be very useful in helping scientists understand how an object like a black hole, neutron star, or active galaxy produces light, how fast it is moving, and what elements it is composed of. Spectra can be produced for any energy of light, from low-energy radio waves to very high-energy gamma rays.
The science of spectroscopy is quite sophisticated. From spectral lines astronomers can determine not only the element, but the temperature and density of that element in the star.
The Hertzsprung–Russell diagram (abbreviated as H–R diagram, HR diagram or HRD) is a scatter plot of stars showing the relationship between the stars’ absolute magnitudes or luminosities and their stellar classifications or effective temperatures. The diagram was created independently in 1911 by Ejnar Hertzsprung and by Henry Norris Russell in 1913, and represented a major step towards an understanding of stellar evolution.
Exoplanets 太阳系外行星
太阳系外行星或系外行星是位于太阳系之外，围绕太阳以外的恒星公转的行星。截至2024年4月1日，有4,161个已知的系外行星系统，合共有5,653颗已确认的系外行星，其中896个系统拥有不止一颗行星。 系外行星的第一个可能证据是在1917年被发现的，但当时没有得到认可。1992年才首次确认了系外行星的发现。
Reflexive motion:
- Other planets orbit other stars
- Nearly 2000 have been found
- transists
- Doppler shift
地球之所以有生命，主要是因为它有水，且距离太阳不远不近，温度适中，从而是水以三种状态存在。水作为一种化学反应池，生命得以演化。habitable zone.
It needs to be the right temperature to sustain liquid water. It needs to be rocky planet.
Brown Dwarfs 褐矮星
Despite their name, brown dwarfs can be up to 70 times more massive than gas giants like Jupiter. Brown dwarfs form like stars do, by the contraction of gas that collapses into a dense core under the force of its own gravity, whereas planets form from the accumulation of leftover debris from these stellar births.
褐矮星是质量介于最重的气态巨行星和最轻的恒星之间的一种次恒星，具体而言，质量介于13至75或80倍木星质量，或大约2.5×10²⁸ kg 至大约1.5×10²⁹ kg。低于这个范围的是次褐矮星，质量在这之上的是最轻的恒星红矮星。褐矮星可能只有对流，而没有分层或化学分化深度。
Low Mass Stars
Low mass stars live a long time, fusing all their hydrogen into helium over a trillion years. More massive stars like the Sun live shorter lives. They fuse hydrogen into helium, and eventually helium into carbon(also some oxygen and neon). When this happens they expand, get brighter, and cool off, becoming red giants. They lose most of their mass, exposing their cores, and then cool off over many billions of years.
Supernova(star explotion)
When a massive star explodes, it’s called a supernova.
White Dwarfs
High Mass Stars
Neutron Stars
Block Holes
Binary and Multiple Starts
Star Clusters
Nebulae(cloud) 星云
Nebula are clouds of gas and dust in space.
A nebula is a distinct luminescent part of interstellar（星际） medium, which can consist of ionized, neutral, or molecular hydrogen and also cosmic dust.
Nebulae are often star-forming regions, such as in the Pillars of Creation in the Eagle Nebula. In these regions, the formations of gas, dust, and other materials “clump” together to form denser regions, which attract further matter and eventually become dense enough to form stars. The remaining material is then thought to form planets and other planetary system objects.
Dust doesn’t emit visible light, but it can affect the visible light from stars if they’re inside the dust cloud or nearby.
tenuous 脆弱的
Orion Nebulae 猎户座
Red from Hydrogen Green from Oxygen
- emission nebula
The Milky Way
The Milky Way is the galaxy that includes the Solar System, with the name describing the galaxy’s appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye.
Galaxies
A galaxy is a system of stars, stellar remnants, interstellar gas, dust, and dark matter bound together by gravity.
Gamma-Ray Bursts
Dark Matter
In astronomy, dark matter is a hypothetical form of matter that does not interact with light or other electromagnetic radiation. Dark matter is implied by gravitational effects which cannot be explained by general relativity unless more matter is present than can be observed.
在宇宙学中，暗物质是指不与电磁力产生作用的物质，也就是不会吸收、反射或发出光。
The Big Bang
Dark Energy
Dark energy, repulsive force that is the dominant component of the universe.
In physical cosmology and astronomy, dark energy is a proposed form of energy that affects the universe on the largest scales. Its primary effect is to drive the accelerating expansion of the universe.
Deep Time
深时是个地质时间概念，于18世纪时由苏格兰地质学家詹姆斯·赫顿提出。 深时的概念源于对自然的观察，并构成对自然进行科学描述的一个基石。早期的田野观察成果包含原始水平原理、地层叠置和事件的空间尺度。
In the history of science, deep time is a relatively recent discovery. Generally, what we mean by deep time is geological time or cosmic time, in other words: billions of years. Astronomers estimate that the big bang happened about 13.8 billion years ago and the earth to have formed 4.54 billion years ago.
Plasma 等离子体
等离子体，又称电浆、电离浆、等离体，是物质状态之一，是物质的高能状态。其物理性质与固态、液态和气态不同。等离子体和气体一样，形状和体积不固定，会依着容器而改变。
Plasma is one of the four common states of matter - solid, liquid, gas, and plasma. Plasma is an electrically charged gas. Because plasma particles have an electrical charge, they are affected by electrical and magnetic fields. This is the main difference between a gas and a plasma.
Space Weather & Solar Wind
The amount of energy, radiation and plasma streaming off the sun into space—collectively known as the solar wind—varies as the sun’s magnetic activity changes. Extreme events, such as CMEs and strong solar flares or storms, generate space weather. Earth’s atmosphere typically acts as an umbrella protecting us from the bulk of the sun’s influence. During severe space weather, however, it can break through this boundary and affect our planet.
Space weather affects the density and turbulence of Earth’s ionosphere. As radio signals travel through this layer of the atmosphere, its changing thickness may send waves on distorted paths, affecting communications transmission. And an influx of particles streaming toward Earth can cause brighter and more widespread auroras, as well as surges in power grids that lead to outages.