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این فرضیه که خورشید در پایان حیات خود تبدیل به یک کره آتشین بزرگ می شود و نیروی جاذبه آن به حدی می رسد که تمام اجرام آسمانی پیرامون خود از جمله سیاره زمین را به طرف خود جذب می کند و در خود می بلعد از مدتها قبل مطرح بود.
. While it is likely that the expansion of the outer layers of the Sun will reach the current position of Earth's orbit, recent research suggests that mass lost from the Sun earlier in its red giant phase will cause the Earth's orbit to move further out, preventing it from being engulfed
parse نوشته است:سلام!
ضمن تشکر از دقت نظر استاد گرامی کیهانشناس عزیز!
هرچند که با فرمایش جنابعالی موافقم ولی دوست گرامی ابرمکعب عزیز نیز تنها نقل قول
فرمودند و صحت مطلب بر عهده نویسنده اصلی آن است.
البته منظورم خبری که گذاشتید هست
به نظر دوستان نمیتونه موضوع جالبی برای بحث باشه

^ a b Pogge, Richard W. (1997). The Once and Future Sun (lecture notes). New Vistas in Astronomy. The Ohio State University (Department of Astronomy). Retrieved on [b][color=#800000]2005-12-07[/color][/b]"A minor academic debate among astronomers is the final fate of the earth. As the sun ages and enters the red giant stage of its life, it will heat up, making the earth inhospitable. It will also expand, driven by helium fusion so that its outer layers reach past the earth's current orbit. Previously it had been believed that the sun would lose enough mass to allow earth to escape to a more distant orbit, lifeless but intact. However, new calculations, which take into account tidal forces and drag from mass shed by the sun, suggest that the earth will have sufficiently slowed in that time to be dragged down to its utter destruction in 7.6 billion years. "
and
ScienceDaily (Feb. 24, 2008) — New calculations by University of - astronomers predict that the Earth will be swallowed up by the Sun in about 7.6 billion years unless the Earth’s orbit can be altered.
Dr Robert Smith, Emeritus Reader in Astronomy, said his team previously calculated that the Earth would escape ultimate destruction, although be battered and burnt to a cinder. But this did not take into account the effect of the drag caused by the outer atmosphere of the dying Sun.
He says: "We showed previously that, as the Sun expanded, it would lose mass in the form of a strong wind, much more powerful than the current solar wind. This would reduce the gravitational pull of the Sun on the Earth, allowing the Earth's orbit to move outwards, ahead of the expanding Sun.
“If that were the only effect the Earth would indeed escape final destruction. However, the tenuous outer atmosphere of the Sun extends a long way beyond its visible surface, and it turns out the Earth would actually be orbiting within these very low density outer layers. The drag caused by this low-density gas is enough to cause the Earth to drift inwards, and finally to be captured and vaporised by the Sun.”
The new paper was written in collaboration with Dr Klaus-Peter Schroeder, previously at -, who is now in the Astronomy Department of the University of Guanajuato in Mexico.
Life on Earth will have disappeared long before 7.6 billion years, however. Scientists have shown that the Sun's slow expansion will cause the temperature at the surface of the Earth to rise. Oceans will evaporate, and the atmosphere will become laden with water vapour, which (like carbon dioxide) is a very effective greenhouse gas. Eventually, the oceans will boil dry and the water vapour will escape into space. In a billion years from now the Earth will be a very hot, dry and uninhabitable ball“If that were the only effect the Earth would indeed escape final destruction. However, the tenuous outer atmosphere of the Sun extends a long way beyond its visible surface, and it turns out the Earth would actually be orbiting within these very low density outer layers. [color=#0000FF]The drag caused by this low-density gas is enough to cause the Earth to drift inwards[/color], and finally to be captured and vaporised by the Sun.”hypercube نوشته است:با سلام خدمت اساتید گرامی
فرضیه ای که در بالا از سایت ویکی برداشت و توسط cosmologis مطرح شد مربوط به تحقیقات 3 سال پذشته است.
اگر به تاریخ درج آن دقت می کردید متوجه می شدید.
- کد: انتخاب همه
^ a b Pogge, Richard W. (1997). The Once and Future Sun (lecture notes). New Vistas in Astronomy. The Ohio State University (Department of Astronomy). Retrieved on [b][color=#800000]2005-12-07[/color][/b]
ویکی دانشنامه است . اخبار آن همیشه بروز نیست.
محاسبات اخیر در مورد جرم خورشید نشان می دهند که خورشید جرم لازم برای پس زدن زمین از مدارش را ندارد .
- کد: انتخاب همه
"A minor academic debate among astronomers is the final fate of the earth. As the sun ages and enters the red giant stage of its life, it will heat up, making the earth inhospitable. It will also expand, driven by helium fusion so that its outer layers reach past the earth's current orbit. Previously it had been believed that the sun would lose enough mass to allow earth to escape to a more distant orbit, lifeless but intact. However, new calculations, which take into account tidal forces and drag from mass shed by the sun, suggest that the earth will have sufficiently slowed in that time to be dragged down to its utter destruction in 7.6 billion years. "
and
ScienceDaily (Feb. 24, 2008) — New calculations by University of - astronomers predict that the Earth will be swallowed up by the Sun in about 7.6 billion years unless the Earth’s orbit can be altered.
Dr Robert Smith, Emeritus Reader in Astronomy, said his team previously calculated that the Earth would escape ultimate destruction, although be battered and burnt to a cinder. But this did not take into account the effect of the drag caused by the outer atmosphere of the dying Sun.
He says: "We showed previously that, as the Sun expanded, it would lose mass in the form of a strong wind, much more powerful than the current solar wind. This would reduce the gravitational pull of the Sun on the Earth, allowing the Earth's orbit to move outwards, ahead of the expanding Sun.
“If that were the only effect the Earth would indeed escape final destruction. However, the tenuous outer atmosphere of the Sun extends a long way beyond its visible surface, and it turns out the Earth would actually be orbiting within these very low density outer layers. The drag caused by this low-density gas is enough to cause the Earth to drift inwards, and finally to be captured and vaporised by the Sun.”
The new paper was written in collaboration with Dr Klaus-Peter Schroeder, previously at -, who is now in the Astronomy Department of the University of Guanajuato in Mexico.
Life on Earth will have disappeared long before 7.6 billion years, however. Scientists have shown that the Sun's slow expansion will cause the temperature at the surface of the Earth to rise. Oceans will evaporate, and the atmosphere will become laden with water vapour, which (like carbon dioxide) is a very effective greenhouse gas. Eventually, the oceans will boil dry and the water vapour will escape into space. In a billion years from now the Earth will be a very hot, dry and uninhabitable ball
Updated: 2007 Nov 17
parse نوشته است:با سلام خدمت دوستان عزیز و گرامی! خصوصا ابرمکعب عزیز!
ضمن تشکر از مطالبی که ارائه فرمودید و پیرو فرمایشات استاد کیهانشناس عزیز
به نظرم یک قسمت از این مطلب بسیار جالب آمد و قابلیت این را دارد که بتوانیم
با بحث در مورد آن مطلب جدیدی بیاموزیم:
- کد: انتخاب همه
“If that were the only effect the Earth would indeed escape final destruction. However, the tenuous outer atmosphere of the Sun extends a long way beyond its visible surface, and it turns out the Earth would actually be orbiting within these very low density outer layers. [color=#0000FF]The drag caused by this low-density gas is enough to cause the Earth to drift inwards[/color], and finally to be captured and vaporised by the Sun.”
اگر بنده درست متوجه شده باشم (که اگر اشتباه از برداشت بنده است معذرت می خواهم
و استدعا دارم تصحیح بفرمایید) اینجا گفته شده که
نیروی کششی که از گازهای رقیقی که خورشید را در مرحله غول سرخی ترک می کنند باعث
می شوند که زمین به سمت داخل (به طرف خورشید) کشیده شود. فهم این امر مقداری برای
اینجانب ثقیل و غیر قابل فهم است. خورشید با از دست دادن جرم و انبساط در مرحله غول سرخی
باید با کاهش نیروی گرانش مواجه شود. (البته چون زمین در مدار خود حرکت می کند و در بدو
امر تغییر فاصله ای ندارد کاهش جاذبه بر اثر افزایش شعاع را درک نخواهد کرد. چون از نظر زمین
تمام جرم خورشید در مرکز آن قرار گرفته است و این کاهش تنها بر روی گازهای سطحی خورشید
که آن را ترک می کنند موثر خواهد بود.)
خوب چگونه این نیروی کشندی باعث حرکت زمین به طرف خورشید می شود؟؟
زمین بواسطه کشش گرانشی خود یک برآمدگی کشندی را بر سطح متورم خورشید ایجاد می کند. و یان برامدگی باعث می شود که سرعت حرکت مداری زمین کاهش یابد و همانوطور که در مقدمه ذکر شد این کاهش سرعت منجر به سقوط زمین بدرون منطقه سوزان آن هم در یک مدار مارپیچ خواهد شد.
از سویی چگالی کم اتمسفر رقیق خورشید نیز بسیار زودتر از بخش قابل رویت آن گسترش یافته و زمین را در برمیگیرد



parse نوشته است:
اما به نظرم سقوط زمین بر روی خورشید یک بحث و انبساط خورشید و زوال زمین بر اثر بادهای خورشیدی و یا موج ضربه های
ناشی از وارد شدن خورشید در فاز متغیری بحث دیگری است.
- طبق محاسبات جدید زمین بلعیده خواهید شد.parse نوشته است:سلام!
بیشتر منظور بنده پیش کشیدن یک بحث فیزیکی بود تا نجومی..
parse نوشته است: اما چیزی که در بالا اشاره شده موید این موضوع است که نیروهای کشندی باعث سقوط
زمین بر روی خورشید خواهند شد و نه انبساط و بلعیدن توسط خورشید...
parse نوشته است:اما به هر صورت اگر بحث صرفا بر سر انبساط خورشید باشد که خوب بحث ما عملا منتفی خواهد شد.

کاربران حاضر در اين انجمن: بدون کاربران عضو شده و 1 مهمان