When does Ashura begin and end?

The day before Ashura, which falls on September 20 this year, Muslims observe the sacred day of Tasu’a, the ninth day of Muharram, the first month of the Islamic lunar calendar. Tasu’a marks the preparation of war before the death of Hussein by the armies of his rival Yazid.

Shia Muslim women mourn during a religious procession of the Ashura mourning period on December 6, 2011 in New Delhi, India. Shia men and women dressed in black crying and beating their chests participated in the capital’s processions to mark this important date in the Islamic calendar. DANIEL BEREHULAK/GETTY IMAGES

source:

https://www.newsweek.com/when-ashura-muslim-holiday-commemorates-martyrdom-prophets-grandson-1129535