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： 疑問詞「how」在此引導名詞子句（how people can measure...），作為主要動詞「explains」的受詞。由疑問詞引導的名詞子句（間接問句）必須維持陳述句語序（主詞 + 動詞），不能倒裝。
The scientist explained how the device works under extreme conditions.
這位科學家解釋了該裝置在極端環境下如何運作。
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： 介系詞「by」後接動名詞（-ing 形式，此處為 counting），用來表示達成某動作或目的的「方式、手段」，意為「藉由…… / 透過……」。
You can improve your English pronunciation by listening to native speakers daily.
你可以藉由每天聆聽母語者的發音來改善你的英語發音。
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： 「星空觀察」（Starwatch）是英國《衛報》（The Guardian）極具歷史的天文專欄，致力於向業餘愛好者介紹觀星知識。「秋季四邊形」（Great Square of Pegasus，Pegasus 源自希臘神話中的天馬飛馬座）是北半球秋季夜空中極為顯眼的地標，天文愛好者常以此區域內可見的恆星數量來估算當地的光害與夜空黑暗度。
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： 限制性關係子句（此處由關係代名詞「that」引導）用來修飾並明確說明先行詞。在句中，「that marks the body...」修飾「a pattern of four stars」（四星構成的圖案）。注意子句中的動詞「marks」為單數，因為先行詞核心名詞是單數的「pattern」。
This is a constellation of seven stars that guides travelers at night.
這是一個由七顆星組成的星座，在夜間為旅人指引方向。
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： 結構「a pattern of + 複數名詞」表示由多個元素構成的圖案或排列形式。介系詞片語「of」可以層層遞進以表示所屬或組成關係（例如「of four stars」表示組成，「of a mythical winged horse」表示所屬）。
The ring is made of small diamonds that encircle a blue sapphire.
這枚戒指由圍繞著一顆藍寶石的小鑽石所組成。
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」（神話中長著翅膀的飛馬）指的是希臘神話中的天馬佩加索斯（Pegasus）。在西方天文學中，天馬座在北半球夜空中通常被描繪為倒立的姿態，而「秋季四邊形」（Great Square of Pegasus）正好構成天馬的主軀幹。
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： 情態助動詞被動語態（modal + be + 過去分詞）：結構「can be seen」結合了表示可能性的情態助動詞「can」與被動式「be seen」。當動作的執行者是普遍大眾、顯而易見或不如受詞/現象本身重要時，常使用此結構。
Jupiter can be observed with a small telescope tonight.
今晚用小型望遠鏡就可以觀察到木星。
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： 時間與地點副詞片語的堆疊：英文常將表示時間（如「On 9 November at eight in the evening」）或地點（如「high in the southern sky from London」）的介系詞片語連用。此外，英式英語中日期常寫作「日 月」（如「9 November」），其間不加逗號。
On Saturday at noon, the ceremony will take place in the main hall.
週六中午，典禮將在正廳舉行。
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： 在英國與英式英語出版品（例如《衛報》的「星空觀察」專欄）中，日期習慣以「日月」順序書寫（如「9 November」），中間不加逗號。此外，以「倫敦」作為觀測基準點，是為英國本土的觀星者提供了一個熟悉的緯度基準（約北緯 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： 「形容詞 + enough + 不定詞（to V）」句型表示「足夠……以至於能夠……」。句中採用被動不定詞「to be seen」，因為恆星是被觀察的對象。
The music was loud enough to be heard from down the street.
音樂大聲到連街尾都能聽見。
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： 副詞「even」（甚至、連……都）用於強調令人驚訝或極端的情況。置於介系詞片語「from towns and suburbs」之前，強調即使在光害較嚴重的城鎮與郊區依然能看見。
The summit is visible even on a cloudy day.
即使在陰天，山頂也依然清晰可見。
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： 在天文觀星指南中，區分暗空保護區與「城鎮及郊區」是常見做法；城鎮與郊區的人工光害通常會遮蔽較暗的天體，僅留下最明亮的標誌性恆星可供辨識。
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： 不定詞片語（To try the experiment）放在句首可表示「目的」（意為「為了……」），通常在片語後方加上逗號，再接主要子句。
To get a clear view, we walked up to the top of the hill.
為了獲得清晰的視野，我們走上了山頂。
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： 關係代名詞 which 引導的關係子句（which is away from direct lights）在此作為形容詞子句，修飾前面的名詞（a place），用以具體說明應該找什麼樣的地方。
She chose a hotel which was close to the station.
她選了一家靠近車站的飯店。
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： 在業餘天文觀測或如「星空觀察」這類公民科學活動中，避開局部光害（例如路燈或防盜投射燈）至關重要，這樣人眼才能完成「暗適應」，進而辨認出微弱的星光。
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： 從屬連屬詞「because」引導原因副詞子句，用來解釋主要子句動作（「should then wait」）的原因或理由。
We brought umbrellas because the weather forecast predicted rain.
我們帶了雨傘，因為氣象預報說會下雨。
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： 動詞「adjust」與介系詞「to」連用，形成固定搭配「adjust to」，表示「適應、調整以符合」某種新情況或環境。
It took him several weeks to adjust to the new time zone.
他花了幾個星期才適應新時區。
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： 在業餘天文觀測與觀星活動中，「暗適應」（dark adaptation）是一項關鍵的生理過程。人類的眼睛在全黑環境下需要約 20 至 30 分鐘來合成視紫質（rhodopsin），以啟動夜間視覺。此時哪怕只是看一眼智慧型手機螢幕，強光都會立刻破壞這項適應成果。
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： 情態助動詞被動語態：使用「should not be + 過去分詞 (p.p.)」來表示「不應該被……」，常用於提供客觀建議、指示或規定。
Laptops must not be used during take-off.
起飛期間不得使用筆記型電腦。
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： 原因從屬連接詞「since」：在此處意為「因為」或「由於」（等同於 because 或 as），用來引導表示原因的副詞子句。
We decided to stay home, since the weather was awful.
我們決定待在家裡，因為天氣很糟糕。
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： 在業餘天文觀測中，眼睛的「暗適應」（夜間視力）大約需要 20 至 30 分鐘來合成視紫質。即使只是短暫瞄一眼智慧型手機發出的明亮白藍光，也會立刻破壞這種適應過程並使其歸零；因此觀星者通常會嚴格避免白光，改用微弱的紅光手電筒。
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： 關係代名詞 that 引導的關係子句：子句「that they can see without a telescope」用來修飾名詞片語「every star inside the square」，限定並說明觀察者所要計算的是「不用望遠鏡就能看見的」星星。
Please read the documents that I sent you yesterday.
請閱讀我昨天寄給你的那些文件。
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： 現在分詞片語表伴隨狀況：「ignoring the four corners」是以現在分詞（-ing）引導的片語，作為副詞修飾主要動詞 count，表示在數星星的同時「忽視／略過」四個角落的星星。
He walked out of the room, slamming the door behind him.
他走出房間，順手把門用力關上。
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： 利用肉眼計算特定星座範圍內（如秋季四邊形）可見的星星數量，是國際上評估光害程度與夜空能見度常用的公民科學觀測方法。
EN： The conjunction 'while' is used here to show a direct contrast between two related facts or situations, meaning 'whereas'.
中文： 連詞「while」在此處用來對比兩個相關聯的事實或情況，意思相當於「然而 / 而（whereas）」。
Some people enjoy city life, while others prefer the quiet countryside.
有些人喜歡城市生活，而其他人則偏好寧靜的鄉村。
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： 零條件句（If + 現在簡單式，現在簡單式）用於描述客觀事實、常態或科學量測標準，表示在某條件下必定會呈現的結果。
If the temperature drops below zero, water turns to ice.
如果溫度降到零度以下，水就會結冰。
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： 公民科學計畫常建立簡單的計數標準（例如計算特定星座內可見的恆星數量），讓一般大眾無需昂貴的光度計也能輕鬆量化光害程度。
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： 使用對等連接詞「and」構成的複合句：當連接兩個完整的獨立子句（皆有主詞和動詞）時，通常會在「and」前面加上逗號，呈現平行對比或遞進的語意結構。
Dark clouds suggest rain, and strong winds indicate a storm.
烏雲代表可能下雨，而強風則意味著暴風雨即將來臨。
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」引導的名詞子句：連詞「that」可用來引導名詞子句，充當主要動詞（如 mean、suggest、know）的受詞，其內部包含完整的「主詞＋謂語」結構。
The report indicates that the experiment was successful.
該報告指出實驗非常成功。
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： 公民科學常利用簡便的「數星星」方式來評估光害程度。觀測者無需昂貴的儀器，只要藉由肉眼計算特定星座或星群（如秋季四邊形）內能看見的星星數量，就能推算當地的極限星等與夜空黑暗度。
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： 限制性關係子句以關係代名詞「who」引導，用來具體修飾並限定先行詞指涉的人群。此處「who can count about 35 stars」明確指出是哪一群「觀測者」。
Students who finish the test early may leave the classroom.
提早交卷的學生可以離開教室。
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： 片語動詞「look at」意思是「看著」或「注視」。此處使用現在進行式「are looking at」，描述眼前正在觀看或身處的景象/環境。
You are looking at one of the oldest paintings in the museum.
你眼前所見的是這座博物館裡最古老的畫作之一。
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： 在城市與郊區，嚴重的光害往往讓人只能看到幾顆最亮的星。如果在「秋季四邊形」範圍內能數出 30 顆以上的暗星，代表觀測點處於極佳的極暗夜空，通常只有在偏遠鄉村或特定的暗空保護區（Dark Sky Reserves）才能達到這種條件。
重要單字附有 IPA 發音、定義、例句和互動式測驗。
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）
片語包含類型標示、雙語定義、用法說明和例句。
to become accustomed to a new situation or condition
適應（新環境或條件）
not less than; a minimum of
至少、起碼
at a distance from someone or something
遠離、離開
a prominent asterism in the autumn northern sky formed by four bright stars in the constellation Pegasus
飛馬座四邊形（秋季四邊形）