The night sky is a wonderful thing to gaze upon any time of year. As we stand under the canopy of stars on a clear moonless night, so many questions come to mind. Questions such as the nature of the stars themselves, or can one see the planets of our solar system? The same stars you see tonight have been the entertainment and in some cases, guidance for civilizations dating back thousands of years. In this series, we will reveal the many wonders of the night sky that you can locate and enjoy in Northeastern Ontario.
After a great day of fishing and experiencing nature, the setting Sun turns the page on the menu of activities. Now it is time to relax and look up. As the sky slowly darkens, the brightest stars begin to reveal themselves one by one as fainter ones come into view with every passing minute. After an hour has gone by, we glimpse the glorious greyish band that stretches across the sky overhead from north to south. This is our home galaxy – the Milky Way.
Comparable to looking at a dusty table top edge-on, we see the collective glow of millions of distant suns. Overall, the galaxy contains an estimated 200 billion stars like a cosmic pancake stretched out 100 thousand light years (ly) in length. Keep in mind one light year is close to 10 trillion kilometres. Because of these vast distances, we see everything in the night sky in the past. Even at the mind boggling speed of light (300,000 km/sec) photons from individual stars take decades, centuries, or millennia to reach our eyes.
All stars, including our Sun, were born from vast interstellar clouds called nebulae. Over time, pockets of gas and dust slowly condensed, and collapsed under immense gravity to eventually light up. In our case, the leftover dust formed the planets, moons, asteroids and comets. Stars come in an array of colours, an indicator of its surface temperature. Extremely hot blue stars exhibit surface temperatures more than 25,000 degrees Celsius whereas cooler red ones glow below 2,500 degrees. Our Sun on the colour scale is a yellow G2 star burning at 5,800 degrees Celsius.
The pristine skies of Northeastern Ontario are located far from the glow of light pollution that plagues major cities and large towns. It is estimated that about 80% of the population live under light polluted skies. However, even in the wonderful countryside, the moon on certain nights can wash out most of the fainter stars and celestial objects including the Milky Way. If star gazing is on the agenda when planning your northern get-a-way, check the calendar of lunar phases and if possible plan around new moon. This is the darkest period of the 29.5 day lunar cycle.
EXPLORING THE NIGHT SKY
Now that you have packed those trusty binoculars or a small telescope, let us look at a few celestial objects. We start overhead at the lovely Milky Way and at first glance, notice three brighter than normal stars. This is the “summer triangle” featuring the stars Altair in Aquilla the Eagle located at 16 ly away, Vega in Lyra the Harp 25 ly away and Deneb, the tail of Cygnus the Swan at 1,400 ly from us. Also referred as the “Northern Cross”, the swan represents the great bird in flight with three main stars outlining its outstretched wings. Travel west along the Milky Way to the Swan’s head, named Albireo. A telescope is required to spot this amazing double star with offsetting colours of blue and yellow. Alberio is located 385 ly from us. Stars are mostly named mostly from Arabic, thousands of years ago.
The word planet comes from the Greek meaning “wanderer”, with Saturn and Mars now easily seen low in the southwest sky in the constellation Scorpius the Scorpion. Saturn slowly sinks closer to the horizon each night and will vanish from sight by October. Mars on the other hand keeps moving eastward against the background stars. Over the next few months Mars slowly dims as our distance increases. Move a little east until you come across Sagittarius. First locate the spout of the imaginary “teapot” and move your binoculars up and a bit to the right until you come across a semi-long, foggy object. This is the Lagoon Nebula, located 4,077 ly away. Here we see a stellar nursery that is slowly producing stars. In fact the tiny new star cluster on the left side is only a million years old (mere babies).
Last, we will look at a globular cluster of stars catalogued as M22. Located 10,400 ly away, this compact cluster has an estimated 70,000 stars in it. To locate this cluster, start at the tip of the teapot and move east. This is an easy binocular object.
Until next time, clear skies everyone.
Gary Boyle is past President of the Ottawa Centre of the Royal Astronomical Society of Canada and has been interviewed numerous times on Canadian radio stations. Gary is an astronomy educator and lecturer with a never ending passion of the night sky.
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