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ASTRONOMY COLUMN: Daytime and the sky

Jupiter reigns as the brightest planet in the sky in February. It shines at a brilliant mag. -2.0 mag this month, some 16 times brighter than Mars.
Jupiter. - 123RF Stock Photo

Hi, sky friends. I missed writing for you last month, but here we are back again and hopefully with a new and interesting topic.

I so much love the night time and all of the wonderful sights in the night sky. Yet, like many of you, I can’t always be out there to view. Also, some people don’t like to stay up late, or have illnesses that prevent them from doing so. So here is a look at the daytime sky. You can be out and look up – carefully in the case of the sun, and I’ll discuss that more later. You can even watch from a bed if you are near, and can look through a window.

So let’s start with the obvious, the sun, blue sky, and clouds. The sun is beautiful but you should not look at it directly. Even with your own eye, after a few seconds, you can incur eye damage. In particular – never look at the sun with binoculars or a telescope – instant damage. But you can use Mylar glasses or number 14 welders glass. Perhaps easiest, you can use a pinhole camera (look it up) and view the image created.

In space, the sky is totally black except for the sun, moon, planets and stars, etc. The “blue” is caused by the scattering of light rays by our atmosphere. Then clouds – water vapor – which we can see – and imagine all sorts of wonderful shapes as we daydream, and of course, as it condenses, gives us rain, and other precipitation.

Probably many people have seen it, but perhaps not paid attention to, the moon in the daytime sky. It’s pretty simple – the moon is always there – it has to be “somewhere” so when it’s not up in the night sky, it’s there in the daytime sky. In fact, at new moon, it’s actually in the day sky all day but you can’t look directly at the sun to see it. But try other times. It’s there and it can be eerily beautiful.

Now, the challenge. When Venus is a “morning star,” it will be bright before dawn, and the challenge is to see how long you can follow it after dawn and particularly sunrise. It gets dimmer and dimmer. Right now it’s an “evening star,”  but it will be lost in the sun in the next  months and then will rise as a morning star. Wait for it.

Perhaps the most common other daytime “stuff” are what are commonly called sun dogs, or technically mock suns or Parhelia. Most people have seen the ring around the moon. There is often a ring around the sun also – the Parhelic Circle. It is not always present, but when it’s there, it can be quite colourful. It’s about 22 degrees away from the sun, and the sun dogs will always be just outside. The sun dogs will always be at the same height as the sun. They can be there whether the rest of the circle is or is not. They can be paired – one on each side of the sun – or just one can be present. They can be just white, or can be the colours of the rainbow. They are more frequent in winter.

Then there are sun pillars. These are very common, and seem to be an extension of the sun, above or below itself. What is less common (I’ve not seen it) is the phenomenon called the double sun where there will seem to be an image of the sun just above or more rarely, just below, itself. These are felt to be a part of a sun pillar which seems to be separated from the main pillar.

One last one – “the green flash.” This occurs with the setting sun, just as the last bit of the sun dips below the horizon. You need a clear view of the horizon for this. Happy daytime hunting.

Now back to the night. So what is in our night sky this month of September? Let’s first discuss the planets. The grand show of summer continues to decrease little by little. Mercury already left our evening sky in July/August and will appear as a morning star.

Venus has reigned our skies for months and we are now preparing to lose it as an evening star. At the beginning of September, it is low in the west-southwest and sets about 1.5 hours after sunset. This narrows to less than 50 minutes by month’s end. Venus will disappear into the sun in late October.

Jupiter is still bright. It is relatively low in the southwest, and it too is gradually approaching sunset and disappearance but this will come later.

Saturn is relatively high in the south at dusk, but losing its brilliance.

Finally, Mars, which was so close earlier, is drawing away from us. It will have lost half its brilliance, and at dusk is in the south-southeast.

Now the morning. Mercury has the predawn sky all to itself. It appears low in the east-northeast over half an hour before sunrise by early September. Mercury becomes invisible again, sinking into the sunrise by Sept. 11.

New Moon is Sept. 3

Full Moon is Sept. 24

First day of autumn, the Equinox, is Sept. 22 at 10:15 p.m.

Don’t forget to view the Harvest Moon this month.

That is all folks. See you next month.

Dr. Rolly Chiasson of Summerside is "Your Sky Guy," who writes monthly astronomy columns for the Journal Pioneer.

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