EN： The conjunction 'how' introduces a noun clause ('how people can measure...') acting as the direct object of the verb 'explains'. Noun clauses formed with question words use standard statement word order (Subject + Verb), not inverted question order.
中文： 疑问词“how”在此引导名词子句（how people can measure...），作为主要动词“explains”的受词。由疑问词引导的名词子句（间接问句）必须维持陈述句语序（主语 + 动词），不能倒装。
The scientist explained how the device works under extreme conditions.
这位科学家解释了该装置在极端环境下如何运作。
EN： The preposition 'by' followed by a gerund ('counting') expresses the method or means through which an action is accomplished (answering 'in what way?').
中文： 介词“by”后接动名词（-ing 形式，此处为 counting），用来表示达成某动作或目的的“方式、手段”，意为“借由…… / 透过……”。
You can improve your English pronunciation by listening to native speakers daily.
你可以通过每天聆听母语者的发音来改善你的英语发音。
EN： 'Starwatch' is a long-running astronomy column in the UK's Guardian newspaper that introduces stargazing to amateur sky-gazers. The 'Great Square of Pegasus' (Pegasus is named after the mythical winged horse in Greek mythology) is a prominent landmark of the northern autumn night sky, widely used by astronomers for estimating light pollution.
中文： 「星空观察」（Starwatch）是英国《卫报》（The Guardian）极具历史的天文专栏，致力于向业余爱好者介绍观星知识。「秋季四边形」（Great Square of Pegasus，Pegasus 源自希腊神话中的天马飞马座）是北半球秋季夜空中极为显眼的地标，天文爱好者常以此区域内可见的恒星数量来估算当地的光害与夜空黑暗度。
EN： A defining relative clause (introduced here by 'that') provides essential information to identify or describe the preceding noun. In this sentence, 'that marks the body...' refers back to 'a pattern of four stars'. Note the singular verb 'marks' agreeing with the singular head noun 'pattern'.
中文： 限制性关系从句（此处由关系代词「that」引导）用来修饰并明确说明先行词。在句中，「that marks the body...」修饰「a pattern of four stars」（四星构成的图案）。注意从句中的动词「marks」为单数，因为先行词核心名词是单数的「pattern」。
This is a constellation of seven stars that guides travelers at night.
这是一个由七颗星组成的星座，在夜间为旅人指引方向。
EN： The pattern 'a pattern of + plural noun' describes a shape, configuration, or arrangement made up of multiple elements. Prepositional phrases with 'of' can be chained to show nested possession or composition ('of four stars', 'of a mythical winged horse').
中文： 结构「a pattern of + 复数名词」表示由多个元素构成的图案或排列形式。介词短语「of」可以层层递进以表示所属或组成关系（例如「of four stars」表示组成，「of a mythical winged horse」表示所属）。
The ring is made of small diamonds that encircle a blue sapphire.
这枚戒指由围绕着一颗蓝宝石的小钻石所组成。
EN： The 'mythical winged horse' refers to Pegasus from Greek mythology. In Western astronomy, the constellation Pegasus is depicted upside down in the northern night sky, with the Great Square forming the main torso of the horse.
中文： “mythical winged horse”（神话中长着翅膀的飞马）指的是希腊神话中的天马佩加索斯（Pegasus）。在西方天文学中，飞马座在北半球夜空中通常被描绘为倒立的姿态，而“秋季四边形”（Great Square of Pegasus）正好构成飞马的主躯干。
EN： Modal passive ('modal + be + past participle'): The structure 'can be seen' combines the modal verb 'can' (expressing possibility) with the passive voice 'be seen'. It is used when the performer of the action is general, obvious, or less important than the object/phenomenon itself.
中文： 情态助动词被动语态（modal + be + 过去分词）：结构“can be seen”结合了表示可能性的情态助动词“can”与被动态“be seen”。当动作的执行者是普遍大众、显而易见或不如宾语/现象本身重要时，常使用此结构。
Jupiter can be observed with a small telescope tonight.
今晚用小型望远镜就可以观察到木星。
EN： Adverbial phrases of time and location stacking: English often places prepositional phrases indicating time ('On 9 November at eight in the evening') or location ('high in the southern sky from London') together. Note that in British style, dates commonly appear as 'Day Month' without a comma (e.g., '9 November').
中文： 时间与地点副词短语的堆叠：英文常将表示时间（如“On 9 November at eight in the evening”）或地点（如“high in the southern sky from London”）的介词短语连用。此外，英式英语中日期常写作“日 月”（如“9 November”），其间不加逗号。
On Saturday at noon, the ceremony will take place in the main hall.
周六中午，典礼将在正厅举行。
EN： In the UK and British English publications (such as The Guardian's Starwatch column), dates are customarily written in the day-month order (e.g., '9 November' or '9th November') without a comma separating them. Furthermore, referencing London as an observation point provides a familiar latitude baseline (~51.5°N) for UK stargazers.
中文： 在英国与英式英语出版物（例如《卫报》的「星空观察」专栏）中，日期习惯以「日月」顺序书写（如「9 November」），中间不加逗号。此外，以「伦敦」作为观测基准点，是为英国本土的观星者提供了一个熟悉的纬度基准（约北纬 51.5 度）。
EN： The structure 'adjective + enough + to-infinitive' indicates that someone or something has sufficient degree of a quality to perform an action. In this sentence, the passive infinitive 'to be seen' is used because the stars are being observed.
中文： 「形容词 + enough + 不定词（to V）」句型表示「足够……以至于能够……」。句中采用被动不定词「to be seen」，因为恒星是被观察的对象。
The music was loud enough to be heard from down the street.
音乐大吵到连街尾都能听见。
EN： The adverb 'even' is used to emphasize an extreme or surprising case. Placing it before the prepositional phrase 'from towns and suburbs' highlights that visibility is possible despite light pollution in these populated areas.
中文： 副词「even」（甚至、连……都）用于强调令人惊讶或极端的情况。置于介词短语「from towns and suburbs」之前，强调即使在光害较严重的城镇与郊区依然能看见。
The summit is visible even on a cloudy day.
即使在阴天，山顶也依然清晰可见。
EN： In astronomy and stargazing guides, distinguishing between dark-sky sites and 'towns and suburbs' is standard practice, as light pollution in urban and suburban areas often washes out fainter celestial objects, leaving only the brightest navigational stars visible.
中文： 在天文观星指南中，区分暗空保护区与「城镇及郊区」是常见做法；城镇与郊区的人工光害通常会遮蔽较暗的天体，仅留下最明亮的标志性恒星可供辨识。
EN： An infinitive phrase ('To try the experiment') can be placed at the beginning of a sentence to express purpose (meaning 'in order to'). It is typically followed by a comma before the main clause.
中文： 不定词片语（To try the experiment）放在句首可表示「目的」（意为「为了……」），通常在片语后方加上逗号，再接主要子句。
To get a clear view, we walked up to the top of the hill.
为了获得清晰的视野，我们走上了山顶。
EN： A relative clause introduced by 'which' ('which is away from direct lights') acts as an adjective modifying the preceding noun ('a place'). In this context, it specifies what kind of place should be found.
中文： 关系代名词 which 引导的关系子句（which is away from direct lights）在此作为形容词子句，修饰前面的名词（a place），用以具体说明应该找什么样子的地方。
She chose a hotel which was close to the station.
她选了一家靠近车站的饭店。
EN： In amateur astronomy and citizen science projects like Starwatch, controlling local light pollution (such as streetlights or security lamps) is essential for 'dark adaptation'—allowing human eyes to detect faint celestial bodies.
中文： 在业余天文观测或如「星空观察」这类公民科学活动中，避开局部光害（例如路灯或防盗投射灯）至关重要，这样人眼才能完成「暗适应」，进而辨认出微弱的星光。
EN： The subordinating conjunction 'because' introduces an adverbial clause of reason, explaining why the action in the main clause ('should then wait') is necessary.
中文： 从属连词「because」引导原因状语从句，用来解释主句动作（「should then wait」）的原因或理由。
We brought umbrellas because the weather forecast predicted rain.
我们带了雨伞，因为天气预报说会下雨。
EN： The verb 'adjust' followed by the preposition 'to' forms a phrasal combination meaning to change or adapt in order to fit a new situation or condition.
中文： 动词「adjust」与介词「to」连用，形成固定搭配「adjust to」，表示「适应、调整以符合」某种新情况或环境。
It took him several weeks to adjust to the new time zone.
他花了几个星期才适应新时区。
EN： In amateur astronomy and stargazing, 'dark adaptation' is a critical biological process. The human eye takes approximately 20 to 30 minutes in total darkness to produce rhodopsin (visual purple), enabling sensitive night vision. Even a brief glance at a smartphone screen can instantly destroy this adaptation.
中文： 在业余天文观测与观星活动中，「暗适应」（dark adaptation）是一项关键的生理过程。人类的眼睛在全黑环境下需要约 20 至 30 分钟来合成视紫质（rhodopsin），以启动夜间视觉。此时哪怕只是看一眼智能手机屏幕，强光都会立刻破坏这项适应成果。
EN： Modal passive voice: 'should not be + past participle' is used to express advice, recommendation, or rule against doing something in a passive structure.
中文： 情态助动词被动语态：使用「should not be + 过去分词 (p.p.)」来表示「不应该被……」，常用于提供客观建议、指示或规定。
Laptops must not be used during take-off.
起飞期间不得使用笔记本电脑。
EN： Causal conjunction 'since': Here, 'since' functions as a subordinating conjunction meaning 'because' or 'as', introducing the reason for the main clause's recommendation.
中文： 原因从属连词「since」：在此处意为「因为」或「由于」（等同于 because 或 as），用来引导表示原因的副词从句。
We decided to stay home, since the weather was awful.
我们决定待在家里，因为天气很糟糕。
EN： In amateur astronomy, dark adaptation (or night vision) takes roughly 20 to 30 minutes for human eyes to produce rhodopsin. Even a quick glance at a smartphone's bright white-blue screen can instantly reset this chemical process, which is why stargazers strictly avoid white light and use faint red filters instead.
中文： 在业余天文观测中，眼睛的「暗适应」（夜间视力）大约需要 20 至 30 分钟来合成视紫质。即使只是短暂瞄一眼智能手机发出的明亮白蓝光，也会立刻破坏这种适应过程并使其归零；因此观星者通常会严格避免白光，改用微弱的红光手电筒。
EN： Relative Clause with 'that': The clause 'that they can see without a telescope' modifies the noun phrase 'every star inside the square'. In English, relative clauses provide essential information defining which stars are meant.
中文： 关系代词 that 引导的关系从句：从句「that they can see without a telescope」用来修饰名词短语「every star inside the square」，限定并说明观察者所要计算的是「不用望远镜就能看见的」星星。
Please read the documents that I sent you yesterday.
请阅读我昨天寄给你的那些文件。
EN： Present Participle Phrase for Accompanying Action: 'ignoring the four corners' is a participle clause (-ing form) acting as an adverbial modifier, indicating an action done simultaneously with counting.
中文： 现在分词短语表伴随状况：「ignoring the four corners」是以现在分词（-ing）引导的短语，作为副词修饰主要动词 count，表示在数星星的同时「忽视／略过」四个角落的星星。
He walked out of the room, slamming the door behind him.
他走出房间，顺手把门用力关上。
EN： Counting naked-eye stars within defined constellations (such as the Great Square of Pegasus) is a widely used citizen science method to measure local light pollution and assess night-sky quality.
中文： 利用肉眼计算特定星座范围内（如秋季四边形）可见的星星数量，是国际上评估光害程度与夜空能见度常用的公民科学观测方法。
EN： The conjunction 'while' is used here to show a direct contrast between two related facts or situations, meaning 'whereas'.
中文： 连词「while」在此处用来对比两个相关联的事实或情况，意思相当于「然而 / 而（whereas）」。
Some people enjoy city life, while others prefer the quiet countryside.
有些人喜欢城市生活，而其他人则偏好宁静的乡村。
EN： Zero Conditional (If + Present Simple, Present Simple) is used here to describe a factual rule or general scientific condition where a specific result always follows a condition.
中文： 零条件句（If + 现在简单式，现在简单式）用于描述客观事实、常态或科学量测标准，表示在某条件下必定会呈现的结果。
If the temperature drops below zero, water turns to ice.
如果温度降到零度以下，水就会结冰。
EN： Citizen science projects often establish simple counting scales (like counting visible stars within a known constellation) to help the general public easily quantify light pollution without needing expensive photometers.
中文： 公民科学计划常建立简单的计数标准（例如计算特定星座内可见的恒星数量），让一般大众无需昂贵的光度计也能轻松量化光害程度。
EN： Compound sentence with 'and': Two independent clauses can be joined by a coordinating conjunction (FANBOYS: for, and, nor, but, or, yet, so), usually preceded by a comma when connecting full clauses.
中文： 使用对等连接词「and」构成的复合句：当连接两个完整的独立子句（皆有主语和动词）时，通常会在「and」前面加上逗号，呈现平行对比或递进的语意结构。
Dark clouds suggest rain, and strong winds indicate a storm.
乌云代表可能下雨，而强风则意味着暴风雨即将来临。
EN： Noun clause introduced by 'that': The conjunction 'that' can introduce a noun clause functioning as the direct object of a reporting verb (such as 'mean', 'suggest', or 'know'). The clause has its own subject and predicate.
中文： 由「that」引导的名词子句：连词「that」可用来引导名词子句，充当主要动词（如 mean、suggest、know）的宾语，其内部包含完整的「主语＋谓语」结构。
The report indicates that the experiment was successful.
该报告指出实验非常成功。
EN： Citizen science projects often assess light pollution through simple star-counting methods. Instead of using expensive light meters, observers count visible stars within a known constellation or asterism (like the Great Square of Pegasus) to determine the limiting magnitude and darkness of their local night sky.
中文： 公民科学常利用简便的「数星星」方式来评估光害程度。观测者无需昂贵的仪器，只要藉由肉眼计算特定星座或星群（如秋季四边形）内能看见的星星数量，就能推算当地的极限星等与夜空黑暗度。
EN： A defining relative clause (restrictive relative clause) begins with 'who' to identify or narrow down the specific group of people being referred to. Here, 'who can count about 35 stars' specifies which observers are being discussed.
中文： 限制性关系子句以关系代词「who」引导，用来具体修饰并限定先行词指涉的人群。此处「who can count about 35 stars」明确指出是哪一群「观测者」。
Students who finish the test early may leave the classroom.
提前交卷的学生可以离开教室。
EN： The phrasal verb 'look at' means to direct one's gaze toward something. When used in the present continuous tense ('are looking at'), it can describe what someone is currently viewing or experiencing.
中文： 短语动词「look at」意思是「看着」或「注视」。此处使用现在进行式「are looking at」，描述眼前正在观看或身处的景象/环境。
You are looking at one of the oldest paintings in the museum.
你眼前所见的是这座博物馆里最古老的画作之一。
EN： In urban and suburban areas, severe light pollution often limits visible stars to only the brightest few. Counting upwards of 30 stars within a single constellation frame like the Great Square of Pegasus indicates an exceptionally pristine, dark-sky environment, typically found only in remote rural areas or designated Dark Sky Reserves.
中文： 在城市和郊区，严重的光害往往让人只能看到几颗最亮的星。如果在「秋季四边形」范围内能数出 30 颗以上的暗星，代表观测点处于极佳的极暗夜空，通常只有在偏远乡村或特定的暗空保护区（Dark Sky Reserves）才能达到这种条件。
重要单词附有 IPA 发音、定义、例句和互动式测验。
在本文中： 測量、評估
在本文中： 神話中的、虛構的
在本文中： 郊區、城郊住宅區
在本文中： 觀測者、觀察員
在本文中： 適應、調整
在本文中： 破壞、毀壞
在本文中： 忽視、不計算在內
在本文中： 看得見的、肉眼可見的
在本文中： （天氣或觀測）條件、狀況
在本文中： 極其、異常地（優異地）
片语包含类型标示、双语定义、用法说明和例句。
to become accustomed to a new situation or condition
适应（新环境或条件）
not less than; a minimum of
至少、起码
at a distance from someone or something
远离、离开
a prominent asterism in the autumn northern sky formed by four bright stars in the constellation Pegasus
飞马座四边形（秋季四边形）