From The United States Conference of Catholic Bishops website :
JANUARY 22 DAY OF PRAYER FOR THE LEGAL PROTECTION OF THE UNBORN
The General Instruction of the Roman Missal (GIRM), no. 373, designates January 22 as a particular day of prayer and penance for abortion, called the "Day of Prayer for the Legal Protection of Unborn Children."
Full relevant section from the GIRM:
“373. Masses for Various Needs and Occasions are used in certain situations either as occasion arises or at fixed times.
Days or periods of prayer for the fruits of the earth, prayer for human rights and equality, prayer for world justice and peace, and penitential observances outside Lent are to be observed in the Dioceses of the United States of America at times to be designated by the Diocesan Bishop.
In all the Dioceses of the United States of America, January 22 (or January 23, when January 22 falls on a Sunday) shall be observed as a particular day of prayer for the full restoration of the legal guarantee of the right to life and of penance for violations to the dignity of the human person committed through acts of abortion. The liturgical celebrations for this day may be the "Mass For Giving Thanks to God for the Gift of Human Life” (no. 48/1 of the Masses and Prayers for Various Needs and Occasions), celebrated with white vestments, or the Mass “For the Preservation of Peace and Justice” (no. 30 of the Masses and Prayers for Various Needs and Occasions), celebrated with violet vestments.”
http://usccb.org/prayer-and-worship/resources/january-22-day-of-prayer.cfm
There are probably as many different ways to join in this day of prayer , as there are people who pray about/for this cause. The important part would be that we do, in a particular way, unite ourselves with this intention at the same time everyone else who has been asked is.
The fact that either white or purple(violet) vestments are deemed suitable for liturgical celebration of these intentions, is a testimony indicative of how diverse our sentiments which accompany these prayers can be. . . themes or intentions represented by these two particular liturgical colors include (purple) sorrow, penance, (white) joy, purity, innocence, holiness, glory .
One might just as easily have all of the above sentiments present in their heart as they pray the same intention ,for example, on Wednesday January 22nd :
I might feel sorrow, for times I remained uncomfortably silent about abortion when I shouldn't have - or sorrow for not having prayed more about this tragedy which continues to plague the entire body of humanity. I might wish to offer some penance (however small ) that day, and place it in the hands of Our Blessed Mother - Mary Most Holy , trusting that in her hands, it becomes a powerful prayer. These type of acts express a recognition of the innocence of the newborn child. As redeemed people, loved by God, each and every one of us are all called to holiness according to our state in life – which, when embraced/accepted, should at least give us a glimpse of the promise of future glory in Heaven which God desires for us. Every child God intends for this world is a gift, and every birth should be a cause for great joy; particularly when the child can be welcomed as intended - into a family prepared to receive and care for him or her. Abortion is so diametrically opposed to all of that .One necessarily should wonder ,among the over 40 million little ones aborted annually , how many were meant to be priests . . . how many were intended to be a special gift to humanity such as St. Padre Pio was , or such as St. Charbel was, or as Venerable Bishop Fulton Sheen was ?
The reflection in the above paragraph, mentioned each of the attributes represented by the liturgical colors of purple and white . . . except for purity. Purity was deliberately left out because you and I struggle with purity . . .oops . . . looks like a few more people just woke up.
It’s true ! If we don’t believe that we ourselves personally have a struggle with purity , it would have to be , in my limited opinion, attributed to our own personal definition of purity being too narrow, or incomplete.Try for a moment, comparing our own personal notion of the meaning of purity with the comprehensive definition of purity which comes to us from Father John Hardon’s Catholic Dictionary :
PURITY.
Freedom from anything that weakens or impairs or changes the nature of a being or its activity. Purity of faith means the absence of error or what is contrary to the revealed truth; purity of intention is the exclusion of self-will in the desire to perform the will of God; purity of conscience is the absence of any sense of guilt in the performance of a moral action; purity of morals commonly refers to the virtue of chastity and therefore freedom from wrongdoing in sexual activity, but on a broader level it means the absence of misbehaviour, especially in one's external or publicly recognizable conduct. (Etym. Latin puritas, clearness, cleanness, uprightness.)
http://www.therealpresence.org/dictionary/adict.htm
In the above, I see so many different ways that I now have to offer some type of prayer, some action, to God tomorrow ; being careful to place it safely in the loving hands of Our Lady of Purity, as a prayer for the legal protection of the unborn ; for the protection of the little ones whom She carries with such motherly concern, in Her Immaculate Heart.
Although I may not be an American , tomorrow I'll definitely be praying as if I am , in union with the USCCB's intentions.
(Also from Modern Catholic Dictionary, Fr. John Hardon, S.J.) :
PURPLE.
A color emblem of penance or sorrow used during the penitential seasons of Lent and Advent, except on saints' days and on the two Sundays when the color rose may be substituted. Purple may also be used (or white) in the eucharistic liturgy and Divine Office for the Dead.
WHITE.
The liturgical color for all feasts of the Trinity, Our Lord (except his Cross and Passion), the Blessed Virgin, angels, all saints except martyrs, and on Sundays during Easter Season; also in the celebration of the sacraments that do not imply penance or the remission of sins. White is a symbol of joy, purity, innocence, holiness, and glory. Pope St. Pius V (reigned 1566-72) prescribed that the ordinary papal attire be white.
http://www.therealpresence.org/dictionary/adict.htm