This day is called Pradosham.
In all Shiva Temples special pujas are conducted in twilight on this auspecious day. It was believed that on this day Lord Shiva performed the cosmic dance in front of Godess Parvati and was witnessed by all the Devtas in Heaven.
Some people keep fast on that day and visit temples and attend pujas and prayers to get their wish fulfilled.
With best wishes
Myth is the greatest human weaknes.
Pradhosha pooja is one the most important pooja offered to Lord Shiva. It is observed 15 moon days from new moon to full moon and 15 moon days ( Shukla Paksha) from full moon to new moon (Krishna Paksha) the evening of the trayodasi (13th moon day) between 4.30 p.m to 6.00 p.m is called Pradhosha. Praying in that time will free us from out sins and gives moksha.
Once Devas and Asuras uing the serpernt Vasuki were trying to get Amurutham from the ocean. That time the terrible poison came out. To rescue all Lord Shiva ate that poison. On the 12th day of moon they got amrutham. ON thryodhai (13th moon day) they realised that they did not pray Lord Shiva and thank him. They pleaded to forgive. Lord Shiva forgave them.
Who ever prays in the Pradhosha time Lord Shiva fulfills their wishes.
During Pradhosha time, worshiping with the following is considered fruitful
Milk gives long life
Ghee gives Moksha state
Honey gives melodious voice
Panjamrutham gives wealth
Lemon removes fear of death
Sandal gives Lakshmi's grace.
Bilvam and flowers can used for Shiva Pooja.
Worship Lord Shiva for every Pradhosham and live happily.