What's Up in the Night Sky -
June
By Fred Barrett
Don’t you dare miss the Venus
transit! It’s an event that won’t happen again for 115 years. It
will occur between 6 p.m. and sunset on June 5. Please protect your
eyes. Use #14 welder’s glasses or solar filters that can be bought
at local optical shops or Focus Scientific in Ottawa. I will be by
the side of regional road 36 about two kilometers south of Highway 7
at that time and will attempt to get some pictures through my 8-inch
telescope. If you want to come by, please do but watch where you
park! It is a narrow area.
This month I thought I would discuss
how astronomers measure how far the stars are. There are five or so
ways of how to make those sorts of estimates but with limited space
I’m going to point out one method that gives us an idea of the
acceleration of the expansion of our Universe, a recent discovery,
and how the measurements were made. I won’t be too technical so
don’t let your eyes glaze over yet! The Universe was once thought
to be in equilibrium but, like life in general, sometimes it’s not
that simple. The Universe will eventually, in numbers of years that
are too large for us to really appreciate (several gazillion years),
expand so far that the stars and the galaxies in the sky will be too
distant to see! The sky will be completely BLACK and empty!
To measure the distance and the
expansion rate of the Universe, astronomers use type IIA supernovas.
The physics behind a stellar explosion like this and the brightness
and energy it generates is completely predictable. Most star systems
aren’t like our own Sun. There are usually two or more stars
orbiting each other in what is called a binary or multiple stellar
system. Over many, many years the stars orbit closer and closer until
they eventually collide. The “luminosity” or amount of energy
that they emit can be calculated very accurately. Allowing for
transparency in the atmosphere and dust clouds that are between the
supernova and our telescopes, their luminosity or energy emission can
be well measured. Their brightness can be measured against a standard
and an estimate of distance calculated. A few years ago, it was
discovered that, according to the theories of that time about what
the Universe was doing, their luminosity was less than it should have
been! They were farther than was expected! Since then, newer theories
have suggested that empty space is actually generating more empty
space and causing the volume of our universe to expand! Who would
have guessed?
This month most of the planets viewable
are in the west after sunset. Saturn is an especially lovely sight
through a moderate size telescope. Last night (May 26) the rings were
well tipped to see divisions in their structure.
This month, the full Moon is on the
4th. There is again a partial lunar eclipse but only seeable way out
west. The Moon is such a fascinating territory to view. I know that I
keep mentioning it, but with a good set of binoculars, you can
discover a whole new world! This month’s full Moon is called by
various Aboriginal and European societies, the Rose Moon, Planting
Moon, Green Corn Moon and Berry Ripening Moon. All names are pretty
accurate even allowing for the weird spring that we have had.
Remember that summer solstice is on
June 20 (7:09 p.m. EDT), and summer officially begins! For us amateur
astronomers, that means that the days get shorter and the nights
longer again. I hate to see winter approach but it really is the best
time to observe! It’s so hard when the Sun goes down so late and it
rises so soon. Summer has the most beautiful constellations but the
shortest time to view them. To mention Saturn again, it’s prominent
in the south in the early evening and right in the middle of Virgo.
Do you remember how to find Virgo? The arc of the handle of the big
dipper points down to Arcturus, a very bright blue star, and then
just “speed on to Spica” and voila, you are in the bottom part of
Virgo. At this time of the year, the band of the Milky Way, our
galaxy of two billion plus stars, is especially prominent and is so
beautiful when you look up high in the night sky, through a simple
set of binoculars – what a universe! There are no meteor showers to
report this month but there are certainly plenty of objects, a
universe of objects, to tour in our dark skies. It’s cheap
entertainment to walk outside where you live out in our rural areas
and, with a little research, show your kids what’s going on or
impress the neighbours with what you know!
On June 27 the moon is about a fist’s
width below Spica and Saturn is quite close as well.
If you want a real challenge, get a
telescope and look for Pluto in Sagittarius. I will leave it to you
to find a star chart and search the sky to find that constellation.
Get star searching!
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..
