Whenever January 1, the solemnity of Mary, Mother of God, or August 15, the solemnity of the Assumption, or November 1, the solemnity of All Saints, falls on a Saturday or on a Monday, the precept to attend Mass is abrogated.

http://www.usccb.org/beliefs-and-teachings/what-we-believe/canon-law/complementary-norms/canon-1246.cfm

Too bad for him it fell on Tuesday.

In either case, the day is "celebrating" something not supported by Scripture.

It's more evidence of the Roman Catholic worship of Mary.

"It's more evidence of the Roman Catholic worship of Mary."

Ah! You are misinformed! It makes me happy to assure you that this is not the case.

At that Mass, as at every Sunday and Holy Day Mass, we all pray together, out loud, the following prayer to GOD ALONE. Please note bolded words:

Glory to God in the highest,
and peace to His people on earth.
Lord God , heavenly King,
Almighty God and Father,
we worship You, we give You thanks,
we praise You for Your glory.
Lord Jesus Christ,
only Son of the Father,
Lord God , Lamb of God ,
You take away the sin of the world:
have mercy on us;
You are seated at the right hand of the Father:
receive our prayer.
For You alone are the Holy One,
You alone are the Lord,
You alone are the Most High,
Jesus Christ, with the Holy Spirit,
in the glory of the Father.
Amen.

Let's have an "Amen" here.