Rahu Kaal (Rahu Kalam)
Rahu Kaal is a daily period of about 90 minutes, one-eighth of the time from sunrise to sunset, that tradition avoids for starting new work. Which eighth it is depends on the weekday.
Also known as: Rahukaal, Rahu Kal, Rahukalam
The full guide: Rahu Kaal: Meaning, Timing by Weekday and What to Avoid
To find Rahu Kaal, the daytime from local sunrise to sunset is divided into eight equal parts. One part, fixed by the weekday, is Rahu Kaal: the 2nd on Monday, 3rd on Saturday, 4th on Friday, 5th on Wednesday, 6th on Thursday, 7th on Tuesday and 8th on Sunday. With a 12-hour day each part lasts 90 minutes; it is longer in summer and shorter in winter.
The custom is strongest in South India, where Rahu Kalam is checked before almost any new undertaking, and it is now followed widely. People avoid it for beginnings such as a puja, a journey, signing papers or a purchase, while work already under way simply continues. Some families use the period for prayer instead, such as the lamp puja to Durga in Tamil Nadu.
Two misunderstandings are common. Rahu Kaal is not tied to where the planet Rahu sits in your chart; it is a fixed weekday pattern. And printed tables that give the same clock times every week assume sunrise and sunset at six o’clock; the real period shifts with your city and the season, so check it locally.