RC Kapoor writes in Current Science:
Two celestial occurrences find place in the incidents related to the great poet – saint Guru Nanak (1469– 1539 CE), founder of Sikhism, or in his teachings. The first one referred to as lamma tara (long star) figures in a hymn in the Sri Guru Granth Sahib and the other is a solar eclipse that occurred while Guru Nanak was visiting Kurukshetra. I conclude that the long star must be Halley’s Comet in its apparition in 1531. This is significant considering that the record of sighting of a comet in an Indian scripture has so far not been identified. Further, among the many eclipses occurring during the relevant period of 1498–1521, that of 13 January 1507 is the most probable one. The eclipse is historical in the sense that it is the first observational record to be depicted in an Indian mural.