Does the day begin from the time of Fajr or midday?

Q 1: When does the day start according to the Islamic law? Does it start at the time of Fajr (Dawn) Prayer or right after midnight as established by astronomers? And what is the proof for that from the Holy Qur'an and the Sunnah (whatever is reported from the Prophet)?

A: The Islamic day starts at the daybreak when the Fajr Prayer is offered. Allah (Exalted be He) said: It is made lawful for you to have sexual relations with your wives on the night of As-Saum (the fast). till His (Exalted be He) Saying: So now have sexual relations with them and seek that which Allâh has ordained for you (offspring), and eat and drink until the white thread (light) of dawn appears to you distinct from the black thread (darkness of night), then complete your Saum (fast) till the nightfall. Moreover, the Prophet Muhammad (peace and blessings of Allah be upon him) said: Verily, Bilal announces the Adhan (call to Salah) during the night, so continue eating and drinking until the second Adhan is raised by Ibn Um Maktum .