# استقرار الجو

Schematic diagram illustrating how optical wavefronts from a distant star may be perturbed by a turbulent layer in the atmosphere. The vertical scale of the wavefronts plotted is highly exaggerated.

استقرار الجو Astronomical seeing هو حالة ثبات الغلاف الجوي واستقراره فحين يكون الغلاف الغازى الجوي غير مستقر تبدو النجوم متلألئة وتقفز الصورة حول التليسكوب ويطلق الفلكيون على هذة الحالة (الاستقرار الجوي الردئ). وحين يكون الغلاف الغازى الجوي ثابتا ومستقرا تكون الصورة صافية واضحة المعالم ويطلق الفلكيون على هذة الحالة (الاستقرار الجوى الجيد).

## فهرست

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## التدابير الفلكية

Simulated negative image showing what a single (point-like) star would look like through a ground-based telescope with a diameter of 2r0. Diffraction makes the image appear blurred. The atmosphere would make the blob move around very rapidly, so that in a long-exposure photograph it would appear more blurred.
Simulated negative image showing what a single (point-like) star would look like through a ground-based telescope with a diameter of 7r0, on the same angular scale as the 2r0 image above. The atmosphere makes the image break up into several blobs (speckles). The speckles move around very rapidly, so that in a long-exposure photograph the star would appear as a single blurred blob.
Simulated negative image showing what a single (point-like) star would look like through a ground-based telescope with a diameter of 20r0. The atmosphere makes the image break up into several blobs (speckles). The speckles move around very rapidly, so that in a long-exposure photograph the star would appear as a single blurred blob.

## المصادر

• مؤمن, عبد الأمير (2006). قاموس دار العلم الفلكي. بيروت، لبنان: دار العلم للملايين. Cite has empty unknown parameter: `|طبعة أولى coauthors=` (help)

Much of the above text is taken (with permission) from Lucky Exposures: Diffraction limited astronomical imaging through the atmosphere, by Robert Nigel Tubbs

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