What is the meaning of this hadith about evil of darkening?

>'The Prophet (ﷺ) looked at the moon and he said': "*O Aishah, do you seek refuge with Allah from the evil of this? For indeed this is Al-Ghasiqu Idha Waqab*" (The darkened one as it darkens) - (أَعُوذُ بِاللَّهِ مِنْ شَرِّ هَذَا الغاسقِ إِذا وَقَب). Narrated in At-Tirmidhi (3366 ) and Abu I'sa classed it Hasan Sahih; it is also narrated in Al-Hakim (2/589 ) who stated its Isnad is Sahih, and Imam Dhahabi agreed; in Musnad Ahmad (24323 , 25711 , 25802 and 26146 ); Ibn Hajar classed it Hasan in Fath al-Bari (8/741 ) I would like to know the meaning of this evil and what is refers to exactly? Is there a commentary or explanation for this narration?