As the sun rises on the summer solstice (the longest day of the year) shafts of light shine directly down the tomb’s passageway to illuminate the chamber within.
Wrth i’r haul godi ar heuldro’r haf (diwrnod hiraf y flwyddyn) mae golau’n tywynnu’n syth i lawr tramwyfa’r beddrod i oleuo’r siambr y tu mewn.