Rahu Kalam:

According to Vedic Astrology, Rahu is an inauspicious planet. Some believe that during Rahu Kalam, there is more exposure to UV rays, which could be harmful to health. Rahu Kalam is described as the darkest period of the day. During this 90-minute term, people face difficulties of different sorts. The foremost difficulty that a person encounters during Rahu Kaal is the lack of constructive, definable thoughts. During the Rahu Kaal duration, there is disharmony in thoughts that can make people judge wrongly and decide wrongly.

As per Vedic Indian astrology, Rahu Kalam or Rahu Kaal is a period that is considered inauspicious for any new venture. Rahu is a shadow planet and king of meteors among the Navagrahas (nine planets) mentioned in Hindu texts.

During the legend known as the Samudra Manthana, an asura named Svarbhanu, disguised as a deva, appears and drinks the nectar of immortality, amrita. Svarbhanu later gets caught and is cut into two pieces by Vishnu’s discus, the Sudarshana Chakra. These two pieces became Rahu and Ketu.

Rahu is considered a malefic planet that tries to eclipse the Sun, and the time it is believed to influence is considered inauspicious.

In Hindu astrology, Rahukala, in Sanskrit, or Rahukalam in Tamil, is considered an inauspicious period, not considered favorable for starting any good deeds. The Rahukala spans for approximately 90 minutes between Sunrise and Sunset. This inauspicious period is strictly avoided while calculating muhurtas. However, routine tasks that have already been started are regarded to be permissible to continue as usual during this period.

Yama Gandam:

Yamagandam is associated with Yama, the son of Planet Sun, who is responsible for carrying the Soul (Atma) to its deserving place upon the death of a person.

It’s calculated by dividing the day into eight parts, each lasting about one and a half hours. Some say that any activity started during Yamagandam can lead to the failure or destruction of the result, and it’s recommended to avoid starting important, money-related, or travel activities during this time.

Yama Kandam is calculated by dividing the day hours (from sunrise to sunset) into 8 sections, where each day has 1.5 hours duration allocated to the son of planet Sun ‘Yama’. This Yama Gandam period varies based on the sunrise and sunset timings. Only death ceremonies are performed during Yamagandam. Avoid commencing important, money-related, or travel activities, during this time. Yamagandam means destructive time.

The last rites or cremation rituals are carried out during this time, signifying the end of a life cycle, hoping that the Atma attains Moksha.

Rahu kalam:

1.30 pm to 3.00 pm

Yamagandam:

6am to 7.30 am

Read more : https://www.astroved.com/astropedia/en/thursday-rahukalam-and-yamagandam-timings