Zohar Pinchas, Vol. 20 (English)/Vol 15 (Hebrew)
The Zohar asks why Malchut is called ‘Moon’? The Hebrew name for ‘Moon’ is ‘לבנה’, meaning ‘white’.
The natural state of Malchut is dark and judgment, that is represented by the red color but when the light of Chokmah that is white joins the ‘fire’ of Binah, it comes down and turns white. Like a metal under strong fire turns from dark to red and white.
Malchut receives light of Chokmah of the left column from Binah. Binah is on the Left but receives her Light from Chokmah.
From Chokmah that is on the right column, Malchut receives the right of Chokmah through Chassed and reveals light of Chassadim. With the power of both, Malchut turns white as it is revealed in the secret of Isaiah 1:18
“אִם-יִהְיוּ חֲטָאֵיכֶם כַּשָּׁנִים כַּשֶּׁלֶג יַלְבִּינוּ”
“Though your sins be as scarlet, they shall be as white as snow”
Malchut can change Judgment דין to Mercy רחמים with the power of the Tzaddikim צדיקים, (Righteous people). The Moon that is the aspect of Malchut is from the side of the Tree of Knowledge Good and Bad. The Klipah is darkness and the evil side. The light that comes from Chokmah to Malchut is like a thin line that can not reveal its light without Chassadim and it appears only at night. (Like the moon that can show its light only at night.) This is the aspect of the state of exile when we are far from the Light and its full revelation. Day time is the aspect of Chessed and the moon’s light is not revealed.
“וְזָרְחָה לָכֶם יִרְאֵי שְׁמִי, שֶׁמֶשׁ צְדָקָה, וּמַרְפֵּא, בִּכְנָפֶיהָ”
“But unto you that fear My name shall the sun of righteousness arise with healing in its wings”
In the Final Redemption, the Light will be revealed in its fullness and will heal the entire world. ‘The sun…’ is the aspect of Zeir Anpin that brings the Light from Binah and ‘…of righteousness’ is ‘צְדָקָה’. It means that the Light from Binah will benefit those who are like a righteous person connecting Malchut to Zeir Anpin. They support the revelation of light in the world of Malchut. With their actions they build a ‘bridge’ to the ‘Sun’, light of Binah, and benefit from it.