Is there any Biblical or historical proof of the ascension of the Virgin Mary into heaven? Is the Assumption a dogma of the faith?

The dogma of the Assumption means the Blessed Virgin's entrance into heaven, body and soul by the power of God. The active term Ascension is used only of Jesus Christ's entrance into heaven by His own divine power.

On Novermber 1, 1950, Pope Pius in union with the collection of world-wide bishops  made the Assumption of Mary a dogma(official belief) of the Catholic Church:  "by the authority of our Lord Jesus Christ, of the Blessed Apostles Peter and Paul, and by our Own authority, We pronounce, declare, and define as devinely revealed dogma:  The Immaculate Mother of God, Mary ever Virgin, after her life on earth, was assumed, body and soul to the glory of heaven." Pius XII, constitution Munificentissimus Deus, III, 44.

Some may think it strange that the Fathers of the first five centuries do not mention it. But as St. Augustine says: "There are many things that the universal Church maintains, and that we reasonably believe were preached by the Apostles, although they never have been put in writing (De Bapt., v., 23). We can readily conjecture reasons for their silence. Perhaps they feared that certain heretics, like the Valentinians, might cite this doctrine in proof of their errors concerning the Body of Christ. Perhaps again they wished to keep the cultus of the Blessed Virgin in the background on account of the prevalent idolatry. Moreover, when bitter controversy was being waged on such important dogmas as the Trinity and the Incarnation, less important doctrines might well be ignored.  It certainly seems most fitting that the body of the Immaculate Mother of God should not taste corruption, and that it should share in the triumph of her Son, the Risen Christ. 

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Kellncr tells us that the feast of the Assumption in the East is older than the sixth century, for it was celebrated by the heretical sects that separated from Rome in the fifth century, viz., the Monophysites, the Nestorians, the Armenians and the Ethiopians (Kellner, The Christian Festivals, 237). The most ancient writer to speak of it in the West is St. Gregory of Tours (593) who writes: "The Lord had the most holy body  of the Virgin taken into heaven, where, reunited to her soul, it now enjoys with the elect, happiness without end" (De Gloria Mart., i., 109). "A doctrine," says Renaudin, "universally held for over thirteen hundred years, could only have originated in a special revelation of our Lord to His Apostles" (La Doctrine de l'Assumption).  

    BIBLIOGRAPHY: Conway, Studies in Church History, 71-87;  Duchesne, Christian Worship, 272; Ernst, Die Leibliche Himmelfahrt Mariae. C. G. Aug., 1927; May, 1928.  ---- D.  July, Oct., 1924.---D.T. i. 2127-2141.---E.T. Aug. 5, 1923.  Hardon, The Catholic Catechism, Chapter 5, pg. 160.