Urban Astronomy – Orion

Posted December 21, 2020

The night sky is pretty much a mystery to most City Dwellers.  The glare of city light drowns out all but the brightest stars – and planets don’t do much better.  If you are interested, I can tell you where to look to see these far-off worlds.  If you were not interested, you would have stopped reading after the first sentence.  So, at this point, I know my audience. 

By the way on the date of this post, you should go out shortly before sunset and look for the Jupiter/Saturn Conjunction in the Southwest sky. Don’t look at the Sun, OK?

By the way, on the date of this post, go out shortly before sunset and look for the Jupiter/Saturn Conjunction.

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So far, I have used the moon as a cursor to point out the planets Venus, Mars, Jupiter and Saturn.  This is four of the five “eyes only” planets and since Mercury is so elusive, we have pretty much run out of subjects.  There is other stuff in the sky, of course and we might just as well look at those.   

As stated in my prolog for this series, the night sky is a mystery to city dwellers and they might find stars interesting.  Why – you may ask – would I be interested in points of white light that never change?  Long ago, people were interested in stars because they clearly documented the progress of the seasons.  If you are a subsistence farmer (and most people were) you had a vested interest in knowing when to plant and when to harvest your crops. 

As these farmers – and later astronomers – studied the stars, they came to know that they are not all the same color and they actually do change – at least some do.  Furthermore, a few of the stars are not actually single points of light, but are surrounded by luminous gas and dust.  Some look like single stars but – under closer observation – are actually double or triple stars.  Some are clusters of stars with likewise interesting traits.

So, this time I’ll send you out to look at the moon and then direct your attention at the constellation of Orion.  The date is December 28, 2020 and time is 2100 (nine PM).  This is Houston and US Central Standard Time, but around this date, if you can find the moon, after sunset, you should be able to find the constellation.  Orion is known for its three bright stars in “Orion’s Belt”, as well as its two brightest stars, Betelgeuse* and Rigel.  You will see them labeled on the skymap, below.

*You may wonder how to pronounce this.  As a young elementary school student, I did too.  Nobody around the elementary school knew either and I called it, “bet” (wager) “tel” (as in telephone) “geeze” (as in geezer).  With accent on the wager.

Nobody had the knowledge to say otherwise until a college Astronomy professor corrected me.  The word sounds just like “Beetle Juice”.

Steve:  Sorry, I didn’t know!

Prof:     It’s OK Mr. Campbell, nobody does at first.”

Obviously, I was not the first ten-year old Astronomy Nerd.

As you see, I have marked Orion with an arrow from the moon to Orion (that I have apparently drawn with a blue crayon).  Also, please note the “A” that I have placed to point out an object to be discussed later.

I will also post a time-lapse photo I made of this region of the sky.  It shows about half of Orion.  I could show you the whole constellation, but this picture was photobombed by a passing helicopter.  You can see that the aircraft had a constant white light and a flashing red one.  I could probably take pictures every night for a year and not capture something like this – that happened by accident alone.

This 10 or 20 second exposure was taken in early 2020.  Of the three stars in Orion’s Belt, you see two, below the big yellow “2”.  I have pictures with all three, but no helicopter.  The big yellow “1” annotates Betelgeuse, the red-hued star that is the brightest of all in the constellation and referred to as “Alpha Orionis” – meaning the brightest star in Orion.  The big yellow “3” shows you Rigel, the second brightest star in Orion (Beta Orionis).

“Hold on there, Laddybuck!” you are saying, “I can clearly see that Rigel (Yellow Three) is much brighter than Betelgeuse.”

At that particular time, it was, indeed.  Betelgeuse is a variable star  and pulsates – not as extremely as that red helicopter beacon, but at least enough to make you all say, “Hold on there, Laddybuck!”

And, in fact this particular dimming of Alpha Orionis was unprecedented.  Please see chart below:

Betelgeuse Brightness 1965 – 2020

As you can see, Betelgeuse’s drop in brightness was the most severe in many decades.  There was actual serious speculation that Betelgeuse was collapsing.  When red supergiant stars (of which Betelgeuse is one) collapse, the result is a catastrophic explosion called a Supernova.  Is Betelgeuse headed that way?  If so, the “Conventional Wisdom” is that – because the star really, really big and is so close to our Solar System, a Betelgeuse Supernova might easily be visible in the daytime…perhaps for months.

I looked up some more recent data and found the answer…Maybe – but not immediately.

Betelgeuse Brightness 9/2018 – 5/2020

You see that the brightness has recovered completely. 

However, who is to say that this unprecedented drop will not be repeated?  It may take some extreme oscillations to trigger the Supernova.

Latest numbers show Betelgeuse dimming again.

I hope you find this interesting.  😉

What’s that?   The “A” on the skymap?

I’ll get back to you on that one…

Hasta Luego,


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