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Finding Planets In The Sky

(Sub-page below "Finding Stuff in the Sky")



Flat Earth Academy offers a more general page about the stuff in the sky over your head. This page concentrates on some oddball "stars", the planets. (It doesn't talk much about the individual planets, by the way.)



When the ancient shepherds and wise men looked at the night sky, they noticed that although what part of the total picture they could see changed hour by hour and season by season, the "stars" were "fixed". There was an unchanging "big picture". The patterns made by the stars didn't change. Much.

With thousands and thousands of unchanging stars, the few "stars" that do move went un-noticed for a while, but once noticed, they were of considerable interest. Some of them are quite bright "stars", and so it was quite easy, for someone familiar with the general "background" stars, to notice the strange ones moving.

Now... none of them "move" like, say, an airplane's lights move across the night sky. But, from day to day, where they are, compared to the fixed stars, was...

Humans have always been fascinated by patterns. A pattern must "mean something"... and if I can be the first to figure out the "something", or if I can merely fool others into believing my interpretation of the patterns, then that can give me an advantage. (Think "astrologers". Today, an amusing diversion on the puzzle page of the newspaper. Not so, in history and earlier. Even recent history: Hitler consulted an astrologer, and treated the "answers" seriously.)

The following shows what someone standing on the site of an ancient observatory in early 2016 will see, looking towards the constellation Libra. You can also see the top of Scorpius. It is a time lapse video of a part of the sky from the 29th of January, to the 3rd of March, 2016. My thanks to the excellent www.stellarium.org for its help in creating the video.

In the video, it is "obvious" that two things are moving. The left hand "star" is the planet Saturn, and the right hand object is Mars.

But the early stargazers did not have Stellarium, or knowledge of the heavenly bodies. Think about it: They actually remembered (or wrote down) what they were seeing from night to night and noticed that some of the "stars" move. And eventually had pretty good records of the pattern. Amazing... really!

(Details: The moon has been deleted from the sky when present. The time shown is NOT the "time of day" as used in everyday life. The images progress from early evening to just before dawn. Libra will be in different parts of the sky on the exact time used for capturing frames. This facilitated getting good registration between frames.)

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Finding slowly moving things

Please remember: No one has ever seen the planets "move across the sky" as in the animation above.

You, by the marvels of modern technology, get instant access, at the hour that suits you, on the date that suits you, to something that shows you in an instant what would take multiple late night visits outdoors, over a period of 32 nights. Each time, you would have to do a careful drawing of What You Saw. You wouldn't, if you were the discoverer of planets know which stars were worth paying attention to. If you went out on the "wrong" night, or concentrated on the wrong bit of sky, you would see no planets.

Examine the two images below. There are two differences between them. One is "easy" to see... the other harder to see.

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I'll show you the differences in a minute.

Of course, capturing (at all) that tiny bit of sky (and it is a tiny bit) before the age of photography would be "a bit" of a challenge.

Accurately capturing the data you see? Next to impossible.

And yet people were making an attempt. Pages and pages were filled with observations of where stars were. (How you say "where" something is in the sky is an interesting exercise all by itself. But let's consider a simple case. You could decide to make a map of "everything" inside the ladle at the end of the Big Dipper's handle.

You could then say "where" things were, just by describing their position relative to the four stars which make the ladle.

Of course what you would see would depend on how good your telescope was. And how clear the air.

If you were very, very lucky, after you'd become the world authority on The Stars In The Ladle, something new would appear in that part of the sky. I wouldn't hold out much hope for the discovery of a new planet. But a comet could appear there. Or a supernova.

A moment ago, I gave you two photos. And there are two differences between them. If you want to spot them for yourself, now is the time, because I am about to give away the answer.

But first: How's this for "bad luck"? (Or, inadequate attention to detail?)

In May 1795, the French astronomer Jérôme Lalande had a team working on writing down where stars are. They twice saw something, and mentioned it in their notes, and should have known that a transient "something" could be important. But they didn't follow up. They probably saw Neptune. It wasn't until the mid 1800's that Neptune's existence, and status as a planet was finally established (WP). (Who "discovered" it then, and how is another interesting story, by the way.)

And LeLande may not have been the first to have missed his chance. Galileo, at the dawn of the telescope age, may also have seen it, and may have noticed it moved.

So... at last an answer to what's different in the two photos.... (Remember: There are two differences.)

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The image above shows you what you see if you are shown the first image briefly, then the second image briefly, then the first again, the second, and so on, for as long as you care to look at the images.

Today, of course, a computer does the "looking", using an analogous technique. Due to variation in the images... real images aren't a nicely "identical" as the two above, a computer can only "sift", and look for possibilities, create a collection of candidates. If you want to help with reviewing the candidates, you can. Real science. Not a science text book, talking about science. You might discover a previously unknown asteroid! See Zooniverse's Asteroid Zoo. (About 6,000 are already known about, so there are probably a few left to find.)

But real people looked at many, many, many real photographs taken through telescopes before computers came along to help with the task.



Yes, but this page is called "FINDING planets in the sky..."

Oops... yes... sorry.

I did have to say a bit about the fact that they "move around", didn't I? And isn't that something "interesting", you were glad to learn about?

Today, if I were you, I'd cheat. I'd go online to someplace like http://www.nakedeyeplanets.com/mars.htm. (Yes, you can change the name of the planet, to find others.)

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Here's a bit of what was there in early November, 2014. It shows you the positions of Mars on different dates. On 1 September, 2014, for instance, it was in the same part of the sky as the zodiac constellation Libra, for instance. And you can find Libra, can't you? (Well, you will be able to, when you have tackled other parts of the Flat Earth Academy, and this "find what it is near, then look there" technique saves you a whole bunch of other hassle. And it will work for you where ever you may be on earth.)

Mars, by the way, moves "quickly", compared to some of the other planets.



We have it so easy

Cast your mind back, again, to the earliest sky gazers.

Pretty early on, they saw that certain constellations were up there, and that they didn't change. My father taught me to find the big dipper when I was a small child, and my great, great, great grandfather could have done the same for his son.

But as they became more expert in "what is up there", they noticed that some "stars" "misbehaved". These were the planets, which have been the subject of this page. (The word "planet" comes from "wanderer").

But just because the early sky gazers notices that some "stars" wandered, it didn't mean they knew they were radically different from all the other twinkly bits. They didn't know they were closer. They didn't know they had orbits, or that our home, the earth, was one to.

Go out and look at a planet. You can't tell from a single naked eye observation that it is a planet! It looks like all the other twinkly bits! (Well, unless you look at a few of the really near, or really big ones really closely. And half the time, I think I imagine the things people claim to see.)

But! The more we looked at the planets, and more importantly the patterns of their movements, certain things became clear.

For a start, you will always see a planet somewhere against a pretty narrow band of background stars. Not coincidentally, that band of background stars contains the zodiac constellations.

The planets, if you watch carefully, night after night, usually move across the sky in one direction.

But... how cool is this?... some of them, once in a while, "go mad", and briefly move "backwards". This really upset some people for a while. All sorts of terrible things were supposed to be more likely during periods when a planet was "in retrograde motion" ("moving backwards", to you and me.)

By a happy coincidence, when I went to find an example of a "where is that planet in the sky" for you, I just happened upon a period when Mars was moving backwards for a while.

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The above shows that Mars was behaving "normally" (right to left, in the image) until the end of February, 2014. It then reversed direction until the middle of May, at which time it went back to behaving normally.

Now... without our modern understanding of the planets, including earth, orbiting the sun, and our modern ideas of the diameter of each orbit, and the speeds the planets are traveling, this "moving backwards" behavior must have been really puzzling. And, as I mentioned, puzzles make people nervous.

But we modern people now have "answers" to everything, and worry less.

But wait a minute. Can you explain why Mars goes backwards? Or do you just take my word for it, without thinking about it for yourself? You have (with just a little checking of Wikipedia for orbital diameters and speeds) everything you need to know to explain the retrograde (backwards) motion.

Of course, that means accepting someone else's idea as to the orbital diameter and speed...

They (diameters and speeds) were worked out from the data collected about the planets' motion across the background stars. That bit of science and maths I don't propose trying to explain. (The fact that I would have to learn the answer myself, first, and it strikes me as a non-trivial task, is a big part of why you are spared.)

If you want to know something about the true dimensions of the solar system... diameters of objects, diameters orbits, you are in luck. I have a page for you about that. (That's where the link in the first sentence takes you.)

"Unchanging" heavens

You think stargazing boring? "Nothing ever changes"?

Just for a start, what part of all the stars you can see changes from season to season, and changes if you travel. In addition...

At the start of this page, I mentioned that the Big Dipper/ Plough has been around, unchanged, for hundreds of years. That doesn't mean that there are no "special events" in astronomy. In my lifetime, I have seen a transit of Venus. Most people will never have the chance. It happens twice in 200 years, but the two transits appear a few years apart. So most people live on transit-less eras. And then, even more remarkably, I saw Mars so close to the earth that it was, to the naked eye, clearly a "disc", not a "twinkly thing". And clearly red. Before our time, Mars has not been so close to earth in any behaviorally "human" human. First time it was been this close in over 50,000 years.





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