The night sky: Matariki heralds Maori New Year

The summer constellations of Taurus and Orion are now setting in the evening twilight. Back in February, these same constellations were high in the northern sky at dusk and didn't set until after midnight.

This inexorable procession in the night sky is caused by the motion of the Earth around the Sun. From our viewpoint on planet Earth, the Sun appears to move eastwards against the distant stars by close to one degree each day. This rate of motion is required because it has to complete exactly one circuit of the sky (360 degrees) every year (365.25 days).

Over a month this small daily movement grows to 30 degrees and the change in position of constellations becomes quite obvious. This daily movement is equivalent to four minutes of time so each day any given star will be found four minutes further towards the west compared to the Sun.

The Sun is passing through the constellation of Taurus which happens to contain a beautiful naked-eye star cluster that has been special to many human cultures. To Europeans it is the Pleiades (or Seven Sisters), to the Japanese it is Subaru and to the Maori it is Matariki. Two weeks ago the Sun passed close to Matariki and is now moving away eastward at four minutes a day. Alternatively, Matariki is moving westward from the sun at the same rate and each day is rising four minutes earlier.

From late May, it becomes possible to glimpse Matariki very low in the east just before sunrise.

It is the new moon following the first sighting of Matariki that marks the start of the Maori New Year for most tribes. The next new moon falls on June 7 and will probably be first visible as a very thin sliver by June 9 at the earliest. On that date Matariki will have risen at 6.15am so with a clear eastern horizon, it could be spotted by keen-eyed observers if the weather allows.

But even if you can't brave the chill pre-dawn air to watch for Matariki, you can still enjoy the sight of Jupiter looking brilliant in the evening sky, contrasting with the rather sparse expanse of Virgo. Jupiter is always one of the most popular objects for telescope viewing by visitors to the Stardome.

By 8pm Jupiter will be due north and if you look behind you will see Crux (the Southern Cross) also reaching its highest point. In the east Scorpius lies above the horizon, while in the west Saturn and Sirius, the brightest star in the sky, are setting.

* Dr Grant Christie is former chairman of the Auckland Observatory and Planetarium Trust Board.