Chaand ki kalaayein: chaand ka aakaar badalta kyon lagta hai

Ek maheene tak chaand ko dekhna

Chapter aapse chaand ki diary banwaata hai (Activity 11.1). Purnima ke agle din suryoday par shuru kijiye, jab chaand paschim ke aasmaan mein aasaani se mil jaata hai. Har din taareekh aur samay likhiye, ek gol ko chhaayankit karke chamakta hissa dikhaiye, aur likhiye ki chamakta hissa badha ya ghata, aur chaand Suraj ke paas dikha ya door. Lagbhag 15 din baad chaand suryoday par nahi dikhta, isliye agle 15 din suryaast par dekhiye. Diary dikhaati hai ki chaand har din alag dikhta hai, har din dikhta bhi nahi, aur roz ek hi samay par aasmaan mein ek hi jagah nahi hota.

Badhta aur ghatta chaand

Purnima se chamakta hissa lagbhag ek hafte mein aadha reh jaata hai aur agle hafte gaayab ho jaata hai: do hafte ka ye ghatta chaand wala samay Krishna Paksha kehlaata hai. Jis din chaand nahi dikhta wo Amavasya hai. Phir chamakta hissa ek hafte mein aadha aur agle hafte poora gol ho jaata hai: ye badhta chaand ya Shukla Paksha hai, jo Purnima par khatm hota hai. Poora chakra, Purnima se Purnima tak, lagbhag 29.5 din ka hota hai. Roshan hisse ka aadhe se kam dikhe to crescent, aadhe se zyada dikhe to gibbous kehte hain.

Chaand ki kalaayein kyon hoti hain

Chaand ka aakaar kabhi nahi badalta. Uski apni roshni nahi hai aur wo Suraj ki roshni lautaakar chamakta hai, isliye Suraj ki or wala aadha hissa hamesha roshan aur baaki aadha andhera rehta hai. Chaand Dharti ka chakkar lagaata hai, aur chaand ka hamesha wahi aadha hissa hamari or rehta hai. Par hamari or wala aadha hamesha roshan aadha nahi hota. Kabhi poora roshan aadha hamari or hota hai, kabhi uska kuch hissa, aur Amavasya ko sirf andhera aadha. Jise hum kala kehte hain, wo bas itna hai ki roshan aadhe ka kitna hissa hum dekh paate hain.

Gend aur lamp ka model

Activity 11.2 ye saaf kar deti hai. Ek chhoti gend mein dandi lagaiye (chaand) aur andhere mein lagbhag 3 m door lamp ya torch (Suraj) ke saamne khade hoiye; aapka sir Dharti hai. Gend ko haath bhar door, sir se thoda upar pakadiye. Lamp ki or munh karke (jagah E) aapko gend ka sirf andhera hissa dikhta hai, Amavasya jaisa. Dheere-dheere ghadi ki sui ki ulti disha mein ghoomiye: ek patli roshan kinaari dikhti hai, jo aadhi aur phir aadhe se zyada ho jaati hai. Lamp ki or peeth karke (A) aapko poora roshan aadha dikhta hai, Purnima jaisa. Roshan aur andhere hisse ke beech ki rekha asli chaand ki tarah ghumaavdaar dikhti hai.

Kaksha mein chaand ke saath

Asli chaand lagbhag ek maheene mein jagah A se ghoomkar waapas A par aata hai. A par hum uska poora roshan aadha dekhte hain (Purnima). B aur H par aadhe se zyada (gibbous), C aur G par theek aadha, D aur F par aadhe se kam (crescent), aur E par kuch nahi (Amavasya). A se E tak chaand ghatta hai aur E se waapas A tak badhta hai. Dharti din mein ek baar ghoomti hai jabki chaand ko chakkar mein ek maheena lagta hai, isliye kisi bhi din Dharti par har jagah log lagbhag ek hi kala dekhte hain.

Kahaan aur kab dekhein

Purnima par chaand lagbhag Suraj ke saamne hota hai: jab Suraj poorab mein ugta hai, chaand paschim mein doobta hai. Agli subahon mein ghatta chaand Suraj ke paas dikhta hai; aadha hone par wo suryoday ke samay sir ke upar hota hai, aur kuch din baad crescent aur bhi paas. Badhta chaand suryaast ke aas-paas aur ghatta chaand suryoday ke aas-paas dekhiye. Chaand kahin bhi ho, uska chamakta hissa Suraj ki or hota hai.

Chaand hamesha suryaast par nahi ugta. Jab tak Dharti ek baar ghoomti hai, chaand apni kaksha mein aage nikal jaata hai, isliye chaand ke waapas usi jagah aane ke liye Dharti ko lagbhag 50 minute aur ghoomna padta hai. Akhbaaron ya India Meteorological Department ke Positional Astronomy Centre mein chandroday ka samay roz lagbhag 50 minute aage khisakta hai: 7 April 2025 ko chandroday 14:23 par tha aur agle din 15:17 par. Isiliye chaand aksar dopahar ke aasmaan mein dikhta hai.

Dharti ki chhaaya nahi

Ek aam galti ye sochna hai ki Dharti ki chhaaya kalaayein banaati hai. Jab Dharti ki chhaaya chaand par padti hai, to chandra grahan hota hai, jo sirf Purnima par ho sakta hai; surya grahan sirf Amavasya par ho sakta hai. Zyaadatar maheenon mein grahan nahi hota, kyonki chaand ki kaksha Suraj ke chaaron or Dharti ki kaksha se thodi jhuki hui hai.

Aur padhein: calendar kaise bane?, kritrim upgrah, chapter ke notes aur NCERT solutions.