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مصطلح في المعجم: الطَّوْر

الوصف: في علم الفلك، يشير "الطور" إلى شكل الجزء المُضاء من جرم سماوي مثل القمر أو كوكب كما يُرى من الأرض.

- أي جرم كروي مثل القمر أو كوكب، يُضيء نصفه فقط من جهة الشمس.
- لكن المراقب على الأرض لا يرى دومًا هذا النصف المضيء بالكامل.
- "الطور" هو النسبة التي نراها من الجزء المُضاء.
- يتغير الطور حسب موقع القمر أو الكوكب بالنسبة للشمس والأرض.

أشهر مثال:
أطوار القمر، التي تتغير خلال شهر تقريباً حسب حركة القمر حول الأرض.
- البدر: نرى الوجه المضيء بالكامل.
- المحاق: لا نرى أي جزء مضاء.
- التربيع الأول والثاني: نرى نصف الوجه المضيء.
- الهلال: نرى جزءًا صغيرًا من الجزء المضيء.

الطور لا يخص القمر فقط، بل يظهر أيضاً للكواكب مثل الزهرة وعطارد، ويمكن رصد تغيّر أطوارها بالتلسكوب.

مصطلحات ذات صلة:



اطّلع على هذا المصطلح بلغات أخرى

حالة المصطلح والتعريف: تمت الموافقة على التعريف الأصلي لهذا المصطلح باللغة الإنجليزية من قبل فلكي باحث ومعلم
ترجمة هذا المصطلح وتعريفه ما تزال بانتظار الموافقة

The OAE Multilingual Glossary is a project of the IAU Office of Astronomy for Education (OAE) in collaboration with the IAU Office of Astronomy Outreach (OAO). The terms and definitions were chosen, written and reviewed by a collective effort from the OAE, the OAE Centers and Nodes, the OAE National Astronomy Education Coordinators (NAECs) and other volunteers. You can find a full list of credits here. All glossary terms and their definitions are released under a Creative Commons CC BY-4.0 license and should be credited to "IAU OAE".

إذا لاحظت خطأً واقعيًا أو خطأً في الترجمة ضمن هذا المصطلح في المعجم، فيرجى التواصل معنا.

بلغات أخرى

وسائط ذات صلة


Venus changes from being small and almost full to being large with only a thin crescent illuminated.

A Matter of Perspective

الشرح: Second place winner in the 2023 IAU OAE Astrophotography Contest, category of Still images of phases of Venus. This exquisite series of images, captured from Santo Domingo, Dominican Republic, between 17 December 2019 and 25 May 2020, shows the phases of Venus as seen from Earth. As Venus and Earth orbit the Sun, we observe different portions of Venus’s sunlit half, similar to the Moon’s phases. The sequence clearly shows Venus as distant, small, bright and gibbous in the lower frames, and ends with Venus reaching the biggest apparent size of all planets (upper frames), very close to the Sun with a small elongation, and appearing as a thin crescent. In the last frame, only 2.8% of the planet’s surface is illuminated.
المصدر: Christofer Baez/IAU OAE (CC BY 4.0)

License: CC-BY-4.0 المشاع الإبداعي نَسب المُصنَّف 4.0 دولي (CC BY 4.0) أيقونات


At the top Venus is full and appears small. As the images progress it moves to half, crescent and new, appearing larger.

Phases of Venus

الشرح: First place winner in the 2023 IAU OAE Astrophotography Contest, category of Still images of phases of Venus. This is a mesmerising series of images of Venus captured from Surgères, Charente-Maritime, France, over a period of six months in 2015. The phases appear similar to the phases we see of our own Moon and occur for similar reasons. Only half of Venus is illuminated by the Sun and, from Earth, we can sometimes only see part of that illuminated half, depending on the relative positions of the Sun, Earth and Venus. Both Mercury and Venus exhibit phases because their orbit is between the Sun and the orbit of Earth. Depending on the position of Venus relative to the Sun and Earth, Venus goes through its phases over a period of time. This sequence of images beautifully showcases the transition from the ‘gibbous’ to the slender crescents. The use of infrared filters helped to capture Venus's dense perpetual cloud cover during daylight in sharp detail, providing a glimpse into the mysterious nature of the planet’s atmosphere.
المصدر: Stephane Gonzales/IAU OAE (CC BY 4.0)

License: CC-BY-4.0 المشاع الإبداعي نَسب المُصنَّف 4.0 دولي (CC BY 4.0) أيقونات


Mercury appears smaller and fainter than Venus. The bottom right of Venus is an illuminated crescent.

Venus and Mercury Trails

الشرح: Honorable mention in the 2023 IAU OAE Astrophotography Contest, category of Still images of phases of Venus. In this composite image, both Mercury (left) and Venus (right) can be seen heading into the sunset. The phases of each are beautifully captured as they descend. Not all planets or moons in the Solar System show phases as viewed from Earth. This phenomenon occurs because the orbits of Venus and Mercury are positioned between Earth’s orbit and the Sun, sometimes allowing us to see only part of the illuminated portion of each planet. These phases are similar to the phases we see of our own Moon.
المصدر: Marcella Giulia Pace (CC BY 4.0)

License: CC-BY-4.0 المشاع الإبداعي نَسب المُصنَّف 4.0 دولي (CC BY 4.0) أيقونات