In the Māori language Matariki is both the name of the Pleiades star cluster and also of the season of its first rising  in late May or early June. This is a marker of the beginning of the new year. Different peoples celebrate Matariki at different times; some when Matariki rises in late May or early June while others observe it at the first full moon or first new moon following the rising of Matariki.  In 2018, Matariki begins on 15 June.
Matariki is a shortened version of Ngā mata o te ariki o Tāwhirimātea, or "the eyes of the god Tāwhirimātea", but it is sometimes incorrectly translated as "little eyes".  Similar words do occur in most Polynesian languages, deriving from Proto-Polynesian *mataliki, meaning minute, small; the use of the term for the Pleiades constellation is also ancient and has been reconstructed to Eastern Oceanic.  
The star cluster was important for navigation and timing the seasons. The first rising of the Pleiades and of Rigel (Puanga in northern Māori, Puaka in southern Māori) occurs just prior to sunrise in late May or early June. The actual time for the celebration of Matariki varies, some iwi (tribe or clan) celebrate it immediately, others wait until the rising of the next full moon, or the dawn of the next new moon—and others use the rising of Puanga/Rigel in a similar way.  
In traditional times, Matariki was a season to celebrate and to prepare the ground for the coming year. Offerings of the produce of the land were made to the gods, including Rongo, god of cultivated food. This time of the year was also a good time to instruct young people in the lore of the land and the forest. In addition, certain birds and fish were especially easy to harvest at this time.
The name Matariki is used also for the central star in the cluster, with the surrounding stars named Tupu-ā-nuku, Tupu-ā-rangi, Waitī, Waitā, Waipunā-ā-rangi and Ururangi. 
In 2001 The Māori Language Commission began a move to "reclaim Matariki, or Aotearoa Pacific New Year, as an important focus for Māori language regeneration". Since then it has increasingly become common practice for various institutions to celebrate Matariki   in a range of ways  and over the period of a week or month anywhere from early June to late August.
With the wider recognition, there have been proposals to make Matariki an official holiday in New Zealand—in particular former Māori Party MP Rahui Katene's private member's bill Te Ra o Matariki Bill/Matariki Day Bill, drawn from the ballot in June 2009.
The Bill would have fixed the date of a public holiday using the new moon in June,  however this was later changed to the new moon of the heliacal rising of Matariki when the bill was drawn a month later and set down for introduction into Parliament.  Mayor of Waitakere City Bob Harvey supported the call to make Matariki a public holiday to replace Queen's Birthday,  along with the Republican Movement of Aotearoa New Zealand, which found none of New Zealand's local authorities held celebrations for Queen's Birthday, but many held celebrations for Matariki.  However, the Bill itself did not propose abolishing Queen's Birthday, and was voted down at its first reading. 
As part of the National– Māori Party agreement subsequent to the New Zealand general election, 2011, both parties agreed to support "[a] cultural heritage bill to recognise Matariki/Puanga, and to honour the peace-making heritage established at Parihaka." 
- Matariki, a 2010 New Zealand drama film set in Otara, South Auckland
- Makahiki, an ancient Hawaiian New Year festival
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- Matariki – Māori New Year in Te Ara: the Encyclopedia of New Zealand
- Matariki: Awaiting their Ascent in Tangatawhenua.com
- Matariki Festival
- The First Lunar Month (June - July) at NZ Astronomy