Today is The Spring Equinox, The Wiccan Eostre - Ostara Sabbat
(from http://www.witchology.com/contents/march/ostara.php)
The end of March is the focus for a number of religious and traditional celebrations. As the sun appears to cross the earth's equator on the 20th or 21st of March, entering the Zodiacal sign of Aries, day and night will be equal in length. This astronomical phenomenon is a day anciently revered amongst Pagan peoples. Their festivals included Alban Elfed, the Teutonic festival in honour of Eostre, Roman Hilaria Matris Deûm, Welsh Gwyl Canol Gwenwynol ('Day of the Gorse'), the Wiccan Eostar (Ostara) Sabbat and the Christian Feast of the Annunciantion of the Virgin Mary (Lady Day) as well as Easter itself.
Origins and History of Ostara
Today, Ostara is one of the eight major holidays, sabbats or festivals of Wicca. It is celebrated on the Spring Equinox, which in the northern hemisphere is around the 20th or 21st of March and in the southern hemisphere around the 23rd of September. Its modern revival is linked to some of the oldest traditions of mankind.
The Month of the Goddess
The name is thought to be derived from a goddess of German legend, according to Jakob Grimm in his Deutsche Mythologie. A similar goddess named Eostre was described by the Venerable Bede. Bede indicated that this name was used in English when the Paschal holiday was introduced. Since then this name (not the holiday) has been converted to Easter, or in German Ostern. Some scholars question both Bede's and Grimm's conclusions due to a lack of supporting evidence for this goddess. Others argue that a lack of further documentation is not surprising given that Bede is credited with writing the first substantial history of England (in which he described Eostre as a goddess whose worship had already passed) and Grimm was specifically attempting to capture oral traditions before they might be lost.
Despite these reservations, the idea of Eostre has become firmly established in many minds. Without any consideration of these problems, the folklorist Dr Jonathan Young categorically states:
Easter has deep roots in the mythic past. Long before it was imported into the Christian tradition, the Spring festival honored the goddess Eostre or Eastre.
According to Bede and Einhard in his Life of Charlemagne, the month called Eostremonat/Ostaramanoth was equated with April. This would put the start of 'Ostara's Month' after the Equinox in March. It must be taken into account that these 'translations' of calendar months were approximate as the old forms were predominantly lunar months while the new were based on a solar year. Thus start of 'Eostremonat' would actually have fallen in late March and could thus still be associated with the Spring Equinox.
The holiday is a celebration of spring and growth, the renewal of life that appears on the earth after the winter. In mythology it is often characterized by the rejoining of the goddess and her lover-brother-son, who spent the winter months in death. This is an interesting parallel to the biblical story in which Jesus is resurrected (the reason Christians celebrate Easter), pointing to another appropriation of pre-Christian religious figures, symbols and myths by early Christianity.
Word Origins
Etymologically, Eostre, or, as it is sometimes called, Ostara, may come from the word 'east', meaning dawn. Others have also tried to link Eostre with 'estrogen' and 'estrus'. These words, however, are more widely considered to be derived from the Greek oistros, meaning 'gadfly' or 'frenzy'. Interestingly, the word 'spring' (from to spring, to leap or jump up, burst out, 0ld English springan, a common Teutonic word, ccompare German springen), primarily the act of springing or leaping, is applied to the season of the year in which plant life begins to bud and shoot.
The Antiquity of Ostara
Ostara is a modern Wiccan festival and there is no evidence that Spring Equinox festivals were called by this name in the past. However, there is no direct 'proof' of many Christian or pagan traditions, so a lack of evidence should not necessarily be taken as disproof.