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FRIENDS OF THE PLANETARIUM NEWSLETTER – APRIL 2003
Last month saw the official end of summer with the passing on March 21 of the autumn
equinox. This means that the Sun has crossed the equator and will now shine more directly
for northern hemisphere residents until September when it crosses back to our part of the
world. As winter moves in, the sky darkens much earlier, giving us longer but cooler
viewing evenings. May begins with two meteor showers reaching their peaks on May 3. The
best viewing for these is in the earlier morning hours when frequent meteors should be
visible. May is your last chance to get a good look at Saturn. It is found low in the
northwestern sky as the sky darkens. The rings are tilted towards us at the present time so if
you get a chance to observe Saturn through a telescope, take advantage of it. The view is
quite magnificent. May also heralds an important event for many cultures. Located at a
declination of +24 degrees and right ascension of 03:44 hours, the Pleiades star cluster will
make its reappearance in the predawn sky near the end of the month. This group of stars is
undoubtedly the most famous of the open cluster groups. It can be observed from most
inhabited parts of the Earth. In earlier days the cluster meant so much to so many people. For
instance, its reappearance in the predawn sky signified to the Maori people the beginning of
a new year (the first new moon after the dawn rising actually marked the start of the Maori
new year). Although most frequently called the Pleiades (originally by the Greeks), they are
also known as Matariki (Maori), Subaru (Japan) and many other names in other cultures.
Whilst the dawn rising of the Pleiades in May signified the beginning of the Maori new year,
it also signified to the ancient Greeks the beginning of the navigation period (northern
spring) and its setting in late autumn the close of the navigation season. The weather during
this period was most favourable for sailing and one translation of the word Pleiades is “to
sail”. Many other origins of the word exist but it is most likely that the group is named after
Pleione who was the mother of the seven sisters. Although only six stars are easily observed
with the naked eye these days (one has faded since Greek times), there are between 300 and
500 stars in the cluster. In 1579 a chart was drawn showing eleven of the stars correctly. This
was thirty years before the telescope was invented. Galileo counted 36 with his telescope.
One person has been credited with counting 19 stars without optical assistance. The cluster is
about 400 light years away and formed roughly 50 million years ago, making it very young
by astronomical standards. Some astronomers predict than in about one million years time,
the stars will have moved apart from each other and the cluster will cease to exist. It is likely
that our Sun formed as part of a similar, but smaller, cluster about 4 billion years ago. Its
members have long since drifted apart.
UPCOMING EVENTS
There are two major events happening at the Planetarium in May.
WORLD ASTRONOMY DAY
This annual event takes place on Saturday, May 10. The Planetarium will once again be
holding a free open day from 2 pm. until 8pm. Members of the Hawke’s Bay Astronomical
Society will be on hand to assist with telescope viewing and night sky sessions in the
Planetarium dome. Videos will run continuously in the lecture theatre.
CARTER MEMORIAL LECTURE
This takes place on Thursday, May 15 at 7:30 pm. This year’s speaker is Dr. Ben
Oppenheimer from the Department of Astrophysics at the American Museum of Natural
History. His lecture is entitled “Aliens: The Scientific Search for Life on Other Planets”.
Sounds fascinating! To reserve seats for this lecture, please contact the Planetarium by
telephone, fax or e-mail as soon as possible. Tickets are $10 each.