The phenomenon of Persistent twilight

Very Late and Very Early Fajr Times!!!

Examine the table below. You will notice that Isha time becomes very late and fajr time comes very early, till the difference between them is less than an hour!

You will note that in some summer months Isha prayer times are given for times greater than 24hrs e.g. 2005 May 18th the time given is 24:43 . This means that the prayer time is actually 00:43 on 2005 May 19th!

Obviously, it is very difficult to perform the Isha and fajr prayers or to fast and perform taraweeh prayer in Ramadan.

No Isha times in some summer months

But, you will also note that for some summer months there are no times given for start of twilight or end of twilight. This phenomena is called persistent twilight.

At Northerly Latitudes (beyond 48 e.g. Britain) the features that legally define the true Fajr and Isha during the summer months ( ~25th May to 18th July) seem to be absent. This phenomena is called persistent twilight as you can see in the table below. So, how does one also fast during these months?

You will also note that some twilights do not occur during the summer months. This is because the Sun does not get far enough below the horizon for the twilight to occur. The times given below are unadjusted prayer times when the altitude of the Sun is 17.5 degrees.

’... reproduced, with permission, from data supplied by HM Nautical Almanac Office, Copyright Council for the Central Laboratory for the Research Councils’.

One of the projects the Cambridge Prayer Times Team wish to collaborate on is the observation and recording of the times of the true dawn (subh Sadiq) and Isha insha Allah.