No, 8th September is not a Holy day of Obligation, but it is a Feast Day (The birth of the Virgin Mary). Catholics should celebrate in some way, you can go to Mass, but don't have to; Consider visiting a Shrine of Our Lady and saying the Rosary there, bringing flowers etc...
On the other hand, 8th December, nine months earlier, is the Feast of the Immaculate Conception of Mary, IS a Holy Day of Obligation (Unless it's a Sunday)
No, but December 8 is, the feast of the Immaculate Conception
The three holy days of obligation of the Virgin Mary are:January 1 - Solemnity of Mary, Mother of GodAugust 15 - The Assumption of MaryDecember 8 - The Immaculate Conception of Mary
The nativity of Mary (SEPT 8) is not a holy day of obligation so it is not a sin to miss Mass on that day
There are several feasts and solemnities regarding Mary. The following are Holy Days of Obligation: the Solemnity of Mary, Mother of God (Jan 1), the Solemnity of the Assumption (Aug 15), and the Solemnity of the Immaculate Conception (Dec 8).
Solemnity of Mary, Mother of God, 1 JanuaryEpiphany, 6 JanuaryAssumption of the Blessed Virgin Mary, 15 AugustAll Saints' Day, 1 NovemberFeast of the Immaculate Conception, 8 DecemberChristmas, 25 DecemberThe Holy days of of obligation are the same in Italy as they are elsewhere.
December 8, Feast of the Immaculate Conception, is the only one in AdventClarification:The above information is true in the United States of America and some other countries. However, each country decides which holy days are to be of obligation. Many countries do not observe the Immaculate Conception as a day of obligation. In a few countries the Feast of Our Lady of Guadalupe, December 12, is observed while the Immaculate Conception is not.For lists of Holy Days of Obligation observed in some countries, see the link below.
Roman Catholic AnswerCatholics remember the saints on All Saints Day (1 November), especially those who do not have another feast day. There are many feast days for Mary throughout the year; the three biggest, two of which are Holy Days of Obligation for the Universal Church - Solemnity of Mary, Mother of God (1 January) and the Assumption (15 August), and one, the Immaculate Conception (8 December) is a Holy Day in the United States. Another, Our Lady of Guadalupe on 12 December is a Holy Day of Obligation in Mexico.
September 8, 2013 was a Sunday.
September 8 1979 was a Saturday.
September 8 2020 will be a Tuesday.
September 8 1913 was a Monday.
September 8 1982 was a Wednesday.