Members of the Hamilton Amateur Astronomers club set up at Binbrook Conservation Area to look at Comet NEOWISE and other celestial bodies on July 13.

Carlos Osorio/The Globe and Mail

Comets are like cats, Canadian comet hunter and author David Levy once wrote. They have tails and they do precisely what they want.

Fortunately for backyard stargazers, Comet NEOWISE, a giant ball of ice and gas that is currently hurtling through our planetary neighbourhood, seems to want to put on a show. It is not as easy to spot as some of the great comets of the past. However, it is one of the best in years and makes an easy target for observers with clear, dark skies or even under city lights when helped out with a good pair of binoculars.

The comet was discovered in late March by NASAs Near-Earth Object Wide-field Infrared Survey Explorer, an earth-orbiting satellite whose acronym, NEOWISE, gives the comet its name. Since then, the comet has been racing through the inner solar system, reaching its closest point to the sun on July 3. It is now on the outward leg of its brief visit and for the next week or so will be well-placed for viewing at twilight in the Northern Hemisphere.

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Comet NEOWISE, as seen over the Binbrook Conservation Area.

Carlos Osorio/The Globe and Mail

Comets are icy fragments left over from the formation of the solar system. They range from less than a kilometre to tens of kilometres in diameter and spend most of their time far from the sun where they are too small and too faint to observe.

Its only when a comet draws near to the suns warmth that the celestial magic happens. Frozen gasses, including water vapour and carbon dioxide, which make up the bulk of the comets mass, are released, forming a glowing ball, or coma. Dust particles freed up by the vaporizing ice trail away from the comet, catching the sunlight and forming a tail that grows longer and brighter the closer the comet is to the sun.

All of this looks far better in a photo, where a long exposure can reveal the full extent and colour of the tail in all its glory. In most cases, what the eye sees, is only the diffuse glow of the coma, which may appear as a tiny fuzzball in the sky, sometimes with a stubby tail sticking out to one side.

Thats essentially how Comet NEOWISE appears now and this weekend is prime viewing time across most of Canada. The comet is low in the sky, skirting the northwestern horizon at dusk. To find it, start looking about one hour after sunset roughly 10 p.m. You need a good view to the northwest that is free from obstructions and preferably as dark as possible (I found it by observing from my local schoolyard in Toronto.)

The Globe and Mail (Source: Skyandtelescope.org)

For city dwellers, there are no bright stars in this part of the sky, but the familiar pattern of the Big Dipper can be found by looking higher up, where the dippers handle reaches nearly overhead. The dipper can serve as a guide for where to sweep the sky with binoculars.

If youve seen a comet before, youll know exactly when youve found it. If not, be patient. As long at the northwestern sky is cloud free and you are looking where the map indicates, the comets distinct glow should pop into view.

If you are underwhelmed by what you see, consider that Comet NEOWISE will be about 103 million kilometres away when its at its closest to Earth next week. But by the time it reaches the farthest extent of its elongated orbit, it will be more than 100 billion kilometres away. The comet will not be seen in our skies again till sometime around the 89th century.

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How to find Comet NEOWISE this weekend - The Globe and Mail