What's Up in the Night Sky -
July
By Fred Barrett
What a great Venus transit! I hope you
all saw the excellent article by Julie Druker on the front page of
the June 7th Frontenac News. Check the Frontenac News website
archives if you missed it.
July and August are the glory days for
observing. The Milky Way arches high overhead from the southern to
the northern horizon. Starting In the south is the “Teapot”, an
affectionate name for Sagittarius. It looks just like a teapot!
Moving up through the Milky Way, we quickly come to Aquila, the
Eagle, with its bright star Altair. Moving on we come to the Swan,
Cygnus, at the zenith of the sky and its bright star Deneb. To the
west of Cygnus is Lyra, also called the weaver, since its shape
resembles a yarn spinner. The star Vega at its top is hard to miss.
The three stars Altair, Deneb and Vega
are known as the summer triangle. They offer a handy way to orient
yourself in the summer night sky if you want to venture farther
afield.
To the west of Lyra is Hercules with
its great globular cluster of stars called Messier 13. Next is
Cepheus as we slide down towards the northern horizon. Soon after is
Cassiopeia near the horizon. If you have your binoculars out, there
is a beautiful double cluster of stars that you should be able to
make out just north of Cassiopeia, a beautiful sight.
Don’t forget the Moon. You can see a
lot of detail without having to resort to optical aids. Of course
with binoculars or a modest telescope more detail pops out: craters,
mountains, valleys, plains.
When is the best time to observe the
Moon? If you think it's around full moon you are wrong! In fact this
is the worst time. Sunlight is falling on the moon's surface from
straight overhead when it is full, and it looks like a white plate
with little detail. The best time to observe the Moon is when it is
at one of its two quarters. The sunlight is coming in at an angle
from the left or right at this time. A few days either side of the
quarter Moon is just as good. Pay special attention to the
terminator, the boundary between light and dark. Shadows from surface
features are at their maximum. If you watch long enough, you can
actually see the shadows change in size.
Full Moon for July occurs July 3. It is
variously called the Summer Moon, Hay Moon, Ripe Corn Moon and Full
Buck Moon. Bucks start to grow new antlers at this time. Different
First Nation societies have other names depending on where they live
or lived and the climate their area. The Moon name often has to do
with the growing season or the weather. The next full Moon occurs on
August first and it is called the Grain Moon and Sturgeon Moon.
Sturgeon was more easily caught at this time.
Summer weather has nothing to do with
how far we are from the Sun. As a matter of fact, the Earth is
farthest away from the Sun in the summer. The Earth is at aphelion or
its greatest distance from the Sun on July 4. That distance is 94.5
million miles or about 153 million kilometers.
There is a sight that you should really
try to see in early July. From about July 1st to the 10th and about
an hour before sunrise, look low to the east northeast. The Pleiades,
Jupiter, Venus and the star Aldebaran form a near straight line.
Aldebaran in the middle of the Hyades cluster and the red baleful eye
of the constellation Taurus the Bull, is at the bottom. Venus is
slightly above and very near Aldebaran. Next above is Jupiter and
above it the Pleiades. They get higher as the days go by. Watch them
as the days pass and they slowly change their formation. In mid-July
the crescent moon passes through the formation. I know that dawn
occurs hideously early at this time of year but it is well worth
getting up an hour before the Sun rises at least for one morning to
see this spectacular sight!
Look west southwest about an hour after
sunset from about July 3rd on and you will see Saturn and Mars in the
constellation Virgo near the bright star Spica. If you follow an arc
from the handle of the big dipper you arrive at Arcturus and if you
continue in that arc an equal distance you arrive at Spica. Both
stars are bright. They get closer as the month progresses. Mars
actually passes between Saturn and Spica in mid-August!
There are no meteor showers this month
but I’m giving you a heads up for the marvelous Perseid meteor
shower on August 11th. It will be a moonless night. Conditions
couldn’t be better.
If you have questions or suggestions, Fred Barrett may be contacted at cygnushill@hotmail.com
The Beginner’s Observer’s Guide by
Leo Enright is available at the Sharbot Lake Pharmacy or by
contacting the Royal Astronomical Society of Canada
www.rasc.ca/publications, subscriptions for our very own excellent
Canadian astronomy magazine, Sky News, are also available from RASC..
