It it ok if i pray Asr about 50 minutes before the time for magrib starts? I know that the time for Asr is over when the sun starts to turn yellow but I can't really discern the colour and neither can I find a website that tells the time when Asr ends '
Salam. First of all below is a hadith:(This is in case of necessity but can be applied here)
Prophet (peace and blessings of Allaah be upon him) said: “Whoever catches up with one rak’ah of ‘Asr before the sun sets he has caught up with ‘Asr.” (Narrated by al-Bukhaari, 531; Muslim, 608)
Actually Asr prayer should be prayed early as it is stated in Bukhari as:
Volume 1, Book 10, Number 526 : Narrated by Anas bin Malik "We used to pray the 'Asr and after that if one of us went to Quba' he would arrive there while the sun was still high."
Volume 1, Book 10, Number 525 : Narrated by Anas bin Malik Allah's Apostle used to offer the 'Asr prayer at a time when the sun was still hot and high and if a person went to Al-'Awali (a place) of Medina, he would reach there when the sun was still high. Some of Al-'Awali of Medina were about four miles or so from the town.
Yellowing of sun usually starts about 30 minutes before Maghrib. So the short answer is Yes you can pray 50 minutes before sunset. But good idea is to pray 60-90 minutes before Maghrib.