Explain method for measurement of dimension of a planet or star.

1.	Explain method for measurement of dimension of a planet or star.
Answer» <html><body><p></p>Solution :Angular diameter: From a point on surface of the earth angle subtended at diameter of the earth is called angular diameter `(alpha)`.<br/>Let diameter of the earth is d. <br/>As shown in figure from point of observation on surface of the earth a can be obtained at diametrically opposite point. <br/> <a href="https://interviewquestions.tuteehub.com/tag/distance-116" style="font-weight:bold;" target="_blank" title="Click to know more about DISTANCE">DISTANCE</a> between the earth and planet (Star) is D. <br/> <img src="https://doubtnut-static.s.llnwi.net/static/physics_images/KPK_AIO_PHY_XI_P1_C02_E01_065_S01.png" width="80%"/> <br/> `alpha=(d)/(D)` (radian) <br/> isused to <a href="https://interviewquestions.tuteehub.com/tag/measure-1091857" style="font-weight:bold;" target="_blank" title="Click to know more about MEASURE">MEASURE</a> diameter (d) of the planet. <br/> `I^(@)`(degree) =60. (<a href="https://interviewquestions.tuteehub.com/tag/min-548008" style="font-weight:bold;" target="_blank" title="Click to know more about MIN">MIN</a>) <br/> I. (min)=60.. (<a href="https://interviewquestions.tuteehub.com/tag/sec-1197209" style="font-weight:bold;" target="_blank" title="Click to know more about SEC">SEC</a>) <br/> `I^(@)=3600..` (sec)</body></html>

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