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<!doctype html><html><head><meta charset="utf-8"/><title>explainlikeimfive – ELI5: how did the people hundreds of years ago discover planets?</title><style>html{font-family: 'Arial', 'Helvetica', sans-serif;font-size: 15px;box-sizing: border-box;}div{margin: 0px -5px 0px 0px;padding: 5px;}header{font-weight: bold;}.f{margin-top: 15px;}.o{background-color: #eaeaea;}.e{background-color: #fafafa;}.l1{border-left: 4px solid #3867d6;}.l1 > header, .l1 > a, .l1 > header a{color: #3867d6;}.l2{border-left: 4px solid #e74c3c;}.l2 > header, .l2 > a, .l2 > header a{color: #e74c3c;}.l3{border-left: 4px solid #20bf6b;}.l3 > header, .l3 > a, .l3 > header a{color: #20bf6b;}.l4{border-left: 4px solid #f7b731;}.l4 > header, .l4 > a, .l4 > header a{color: #f7b731;}.l5{border-left: 4px solid #9b59b6;}.l5 > header, .l5 > a, .l5 > header a{color: #9b59b6;}.l6{border-left: 4px solid #fa8231;}.l6 > header, .l6 > a, .l6 > header a{color: #fa8231;}.l7{border-left: 4px solid #a5b1c2;}.l7 > header, .l7 > a, .l7 > header a{color: #a5b1c2;}.l8{border-left: 4px solid #4b6584;}.l8 > header, .l8 > a, .l8 > header a{color: #4b6584;}.l9{border-left: 4px solid #0fb9b1;}.l9 > header, .l9 > a, .l9 > header a{color: #0fb9b1;}.l0{border-left: 4px solid #fd79a8;}.l0 > header, .l0 > a, .l0 > header a{color: #fd79a8;}.m{background-color: #c8ffc8;}.a{background-color: #ffdcd2;}.p{background-color: #b4c8ff;}.n{text-decoration: none;}.D{cursor:not-allowed!important;color:#ccc!important;}</style></head><body><h1><a href="https://www.reddit.com/r/explainlikeimfive/">/r/explainlikeimfive</a> – <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/">ELI5: how did the people hundreds of years ago discover planets?</a></h1><h2>Snapshot taken on Sat 2022-09-24 at 11:48<br/>Posts: 60 – Score: 275 (91% upvoted) – Flair: Planetary Science – Sorted by: confidence<br/>Sticky: No – Spoiler: No – NSFW: No – OC: No – Locked: No</h2><p><em>Snapshot taken from <a href="https://redditarchiver.ailothaen.fr">Reddit Archiver</a> v1.0.0. All times are UTC.</em></p><h3>Original post</h3><div class="b p f l1" id="t3_xm9kun"><header><a href="https://www.reddit.com/u/Maggo6452">Maggo6452</a>, on Fri 2022-09-23 at 21:19</header><p>If I look into the sky and I see two yellow dots it’s all stars for me. Then I hear one of them is mars and I’m like „ok, still looks the same“. How did the people hundred of years ago discover what’s a close planet and what’s a far away star?</p></div><h3>Comments</h3></div><div class="f o l1" id="t1_ipn654y"><header><a href="https://www.reddit.com/u/Gamilon">Gamilon</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipn654y/">Fri 2022-09-23 at 21:22</a> (1) <a href="#t3_xm9kun" class="n P">▣</a> <a href="#" class="n A D">🠉</a> <a href="#t1_ipn6mmm" class="n B">🠋</a> <a href="#t1_ipn654y" class="n S">◯</a></header><p>Stars are very far away, to someone on Earth they move as one across the sky like dots on a dome being rotated overhead.</p></p><p><p>Planets are much closer, they moved in a direction that was different from the stars and could be seen over time doing so. They even at times appear to go "backwards" against the motion of the stars.</p></p><p><p>"Planet" is itself derived from a Greek word for "wanderer"; this included the moon and sun as well as the visible planets since they also did not move with the stars.</p><div class="e l2" id="t1_ipomti7"><header><a href="https://www.reddit.com/u/gogogadgetrage">gogogadgetrage</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipomti7/">Sat 2022-09-24 at 05:04</a> (1) <a href="#t1_ipn654y" class="n P">▣</a> <a href="#" class="n A D">🠉</a> <a href="#t1_ipp0scz" class="n B">🠋</a> <a href="#t1_ipomti7" class="n S">◯</a></header><p>To really understand what is happening you need to start by looking at a model of the earth and the sun traveling in the milky way. I think you can find some good videos quite easily. While watching that video look at the night time of the earth. What you'll see is that the night face of earth is facing different parts of the Galaxy at different times of the year. This is where things like horoscope come from in identifying constellations at different times of the year. Anyway the Galaxy is huge and all the stars are spinning in it. So the position of the various stars will be pretty much the same at a given time of the year. </p></p><p><p>Now look at a model of just the solar system with the sun and all its planets. Pay attention to the position of the planets relative to the night face of earth. Since all the planets are orbiting the sun along their own orbit what is observed from the night face of the earth will vary a lot. Their position between years will change. Sometimes they'll move faster than the other stars sometimes slower or start going in reverse relative to the other stars over days. Because of this planets were identified as special. The word planet means to wander.</p></p><p><p>Copernicus posited the heliocentric model as an explanation for the weird motion of the planets. And that is how planets were identified as other planets orbiting the same sun as earth rather than everything orbiting Earth.</p></p><p><p>Copernicus wasn't completely correct because he didn't say the sun had its own orbit. But this is a relatively recent understanding that was developed.</p></p><p><p>Also stars were observed a lot. Go to a dark skies preserve to see just how visible they are. Everyone got to experience brighter stars than that every day of their life. They were used for navigation for ages. So data and knowledge about their motion has existed for a very long time</p><div class="o l3" id="t1_ipp8erx"><header><a href="https://www.reddit.com/u/marcher138">marcher138</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipp8erx/">Sat 2022-09-24 at 09:59</a> (1) <a href="#t1_ipomti7" class="n P">▣</a> <a href="#" class="n A D">🠉</a> <a href="#" class="n B D">🠋</a> <a href="#t1_ipp8erx" class="n S">◯</a></header><p>Fantastic summary! To continue on because I love this part of history and could talk about it for hours, the common belief before Copernicus was that the planets moved in circles around the Earth, and retrograde (backwards) motion was explained by epicycles: a small circular orbit along the main orbit. Basically, the planets moved in spirals around the Earth. But, as observations got more precise, astronomers had to add more and more epicycles just to make the model match the observation (planets orbited in a circle while orbiting in a circle while orbiting in a circle while...). Copernicus determined that a heliocentric system better matched observations without so many epicycles.</p></p><p><p>BUT, Copernicus' model also required epicycles! Just not as many. That's because he still subscribed to the classical belief that all orbits must be circular, because planets rested on spheres of aether. Brahe disproved that through observation of a comet passing through those spheres, and proposed a hybrid model where the planets revolved around the Sun, but the Sun revolved around the Earth (still in circles). It wasn't until Kepler (Brahe's student) proposed elliptical orbits in a heliocentric model that epicycles were finally shown the door.</p><div class="e l4" id="t1_ippaibo"><header><a href="https://www.reddit.com/u/Fragrag">Fragrag</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ippaibo/">Sat 2022-09-24 at 10:30</a> (1) <a href="#t1_ipp8erx" class="n P">▣</a> <a href="#" class="n A D">🠉</a> <a href="#" class="n B D">🠋</a> <a href="#t1_ippaibo" class="n S">◯</a></header><p>Tycho Brahe's model is absolutely insane when you look at a video of it. Just some beautiful chaos</p></div></div></div><div class="e l2" id="t1_ipp0scz"><header><a href="https://www.reddit.com/u/VolkspanzerIsME">VolkspanzerIsME</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipp0scz/">Sat 2022-09-24 at 08:07</a> (1) <a href="#t1_ipn654y" class="n P">▣</a> <a href="#t1_ipomti7" class="n A">🠉</a> <a href="#t1_ippdiml" class="n B">🠋</a> <a href="#t1_ipp0scz" class="n S">◯</a></header><p>Also I was told planets don't twinkle. Their light is solid and I'm sure that led to curiosity back in the day.</p></div><div class="e l2" id="t1_ippdiml"><header><a href="https://www.reddit.com/u/Eruptflail">Eruptflail</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ippdiml/">Sat 2022-09-24 at 11:10</a> (1) <a href="#t1_ipn654y" class="n P">▣</a> <a href="#t1_ipp0scz" class="n A">🠉</a> <a href="#" class="n B D">🠋</a> <a href="#t1_ippdiml" class="n S">◯</a></header><p>Additionally, planets <em>do</em> look significantly different from stars. Their coloration and size is much different. While OP might not be able to tell them apart, ancient people used stars for navigation and would easily be able to tell a star apart from a planet.</p></div></div><div class="f o l1" id="t1_ipn6mmm"><header><a href="https://www.reddit.com/u/j____b____">j____b____</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipn6mmm/">Fri 2022-09-23 at 21:26</a> (1) <a href="#t3_xm9kun" class="n P">▣</a> <a href="#t1_ipn654y" class="n A">🠉</a> <a href="#t1_ipni4ag" class="n B">🠋</a> <a href="#t1_ipn6mmm" class="n S">◯</a></header><p>In the early days of history, humans spent much time looking at the stars. The skies were clear and there wasn’t much else to do at night. They memorized the locations and when drawing was invented, they drew pictures of them. Sometimes they would notice that one light in the sky slowly moved. Then they would notice the light was different, steadier than then non moving twinkling lights. They were named for the gods. </p></p><p><p>Eventually in the 1600s people invented telescopes to see better and better. And we learned these were balls of rock and gas. Now we have infra red images taken from space and robot ships doing flybys.</p><div class="e l2" id="t1_ipo363i"><header><a href="https://www.reddit.com/u/Zestyclose-Ruin8337">Zestyclose-Ruin8337</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipo363i/">Sat 2022-09-24 at 01:51</a> (1) <a href="#t1_ipn6mmm" class="n P">▣</a> <a href="#" class="n A D">🠉</a> <a href="#t1_ipo56x5" class="n B">🠋</a> <a href="#t1_ipo363i" class="n S">◯</a></header><p>They would also sit in darkened rooms with an open roof in some instances.</p><div class="o l3" id="t1_ipo3n4p"><header><a href="https://www.reddit.com/u/Longshot_45">Longshot_45</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipo3n4p/">Sat 2022-09-24 at 01:55</a> (1) <a href="#t1_ipo363i" class="n P">▣</a> <a href="#" class="n A D">🠉</a> <a href="#t1_ipoam54" class="n B">🠋</a> <a href="#t1_ipo3n4p" class="n S">◯</a></header><p>The motion of the planets as they move across the sky isn't truly linear either, they knew that some planets traveled in a wavy pattern.</p><div class="e l4" id="t1_ipoo9h7"><header><a href="https://www.reddit.com/u/bewitchedfencer19">bewitchedfencer19</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipoo9h7/">Sat 2022-09-24 at 05:21</a> (1) <a href="#t1_ipo3n4p" class="n P">▣</a> <a href="#" class="n A D">🠉</a> <a href="#t1_ipoad0r" class="n B">🠋</a> <a href="#t1_ipoo9h7" class="n S">◯</a></header><p>This is why they were called “planets”. The original Greek means “wanderer”.</p></div><div class="e l4" id="t1_ipoad0r"><header><a href="https://www.reddit.com/u/J_Zephyr">J_Zephyr</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipoad0r/">Sat 2022-09-24 at 02:56</a> (1) <a href="#t1_ipo3n4p" class="n P">▣</a> <a href="#t1_ipoo9h7" class="n A">🠉</a> <a href="#t1_ipo5bf8" class="n B">🠋</a> <a href="#t1_ipoad0r" class="n S">◯</a></header><p>I like when earth laps Mars, Mars draws a circle in the sky. When we believed earth the center of the universe, we assumed Mars was dancing for us.</p></p><p><p>This phenomenon actually suggested to mathematicians that earth was in fact not the center of the universe. So cool!</p><div class="o l5" id="t1_ipom7nd"><header><a href="https://www.reddit.com/u/Zestyclose-Ruin8337">Zestyclose-Ruin8337</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipom7nd/">Sat 2022-09-24 at 04:57</a> (1) <a href="#t1_ipoad0r" class="n P">▣</a> <a href="#" class="n A D">🠉</a> <a href="#" class="n B D">🠋</a> <a href="#t1_ipom7nd" class="n S">◯</a></header><p>Yup, that’s the retrograde motion you see in those old models.</p></div></div><div class="e l4" id="t1_ipo5bf8"><header><a href="https://www.reddit.com/u/Zestyclose-Ruin8337">Zestyclose-Ruin8337</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipo5bf8/">Sat 2022-09-24 at 02:10</a> (1) <a href="#t1_ipo3n4p" class="n P">▣</a> <a href="#t1_ipoad0r" class="n A">🠉</a> <a href="#" class="n B D">🠋</a> <a href="#t1_ipo5bf8" class="n S">◯</a></header><p>They incorporated those funny “retrogrades” into their models… which makes me think of modern physics, if you will humor me.</p></p><p><p>It was a model that worked but wasn’t seeing the universe as it actually was/is. I am just a laymen with strong non-math knowledge of quantum physics, but that’s what I always think of when we struggle to understand what it means. Maybe it’s like looking at the earth as the center of the universe. It doesn’t make sense because we don’t understand the reality of what is happening. However, it’s an amazing model for calculations and predictions. Same as those crazy planet rotations.</p><div class="o l5" id="t1_ipozzgi"><header><a href="https://www.reddit.com/u/_PM_ME_PANGOLINS_">_PM_ME_PANGOLINS_</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipozzgi/">Sat 2022-09-24 at 07:56</a> (1) <a href="#t1_ipo5bf8" class="n P">▣</a> <a href="#" class="n A D">🠉</a> <a href="#" class="n B D">🠋</a> <a href="#t1_ipozzgi" class="n S">◯</a></header><p>All models are wrong, but some are very useful.</p></div></div></div><div class="o l3" id="t1_ipoam54"><header><a href="https://www.reddit.com/u/pdfrg">pdfrg</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipoam54/">Sat 2022-09-24 at 02:58</a> (1) <a href="#t1_ipo363i" class="n P">▣</a> <a href="#t1_ipo3n4p" class="n A">🠉</a> <a href="#t1_ipoexif" class="n B">🠋</a> <a href="#t1_ipoam54" class="n S">◯</a></header><p>The original TV. And no commercials. Albeit limited content, annual reruns and major weather disruptions!</p></div><div class="o l3" id="t1_ipoexif"><header><a href="https://www.reddit.com/u/Aporkalypse_Sow">Aporkalypse_Sow</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipoexif/">Sat 2022-09-24 at 03:39</a> (1) <a href="#t1_ipo363i" class="n P">▣</a> <a href="#t1_ipoam54" class="n A">🠉</a> <a href="#t1_ipov5q2" class="n B">🠋</a> <a href="#t1_ipoexif" class="n S">◯</a></header><p>Put some rope/sticks across the roof in a grid pattern and you have everything needed to watch precise movements.</p><div class="e l4" id="t1_ipoiehp"><header><a href="https://www.reddit.com/u/Zestyclose-Ruin8337">Zestyclose-Ruin8337</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipoiehp/">Sat 2022-09-24 at 04:15</a> (1) <a href="#t1_ipoexif" class="n P">▣</a> <a href="#" class="n A D">🠉</a> <a href="#" class="n B D">🠋</a> <a href="#t1_ipoiehp" class="n S">◯</a></header><p>True. Merlin?</p></div></div><div class="o l3" id="t1_ipov5q2"><header><a href="https://www.reddit.com/u/Y0rin">Y0rin</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipov5q2/">Sat 2022-09-24 at 06:49</a> (1) <a href="#t1_ipo363i" class="n P">▣</a> <a href="#t1_ipoexif" class="n A">🠉</a> <a href="#" class="n B D">🠋</a> <a href="#t1_ipov5q2" class="n S">◯</a></header><p>How do you darken a room?</p><div class="e l4" id="t1_ipovetj"><header><a href="https://www.reddit.com/u/iamnogoodatthis">iamnogoodatthis</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipovetj/">Sat 2022-09-24 at 06:53</a> (1) <a href="#t1_ipov5q2" class="n P">▣</a> <a href="#" class="n A D">🠉</a> <a href="#" class="n B D">🠋</a> <a href="#t1_ipovetj" class="n S">◯</a></header><p>Wait until the sun goes down. If the moon is bright, wait a few days. Repeat.</p><div class="o l5" id="t1_ipovwy1"><header><a href="https://www.reddit.com/u/Y0rin">Y0rin</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipovwy1/">Sat 2022-09-24 at 06:59</a> (1) <a href="#t1_ipovetj" class="n P">▣</a> <a href="#" class="n A D">🠉</a> <a href="#" class="n B D">🠋</a> <a href="#t1_ipovwy1" class="n S">◯</a></header><p>I understand that, but how is that a darkened room?</p><div class="e l6" id="t1_ipoxbsn"><header><a href="https://www.reddit.com/u/iamnogoodatthis">iamnogoodatthis</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipoxbsn/">Sat 2022-09-24 at 07:18</a> (1) <a href="#t1_ipovwy1" class="n P">▣</a> <a href="#" class="n A D">🠉</a> <a href="#" class="n B D">🠋</a> <a href="#t1_ipoxbsn" class="n S">◯</a></header><p>Fair, I didn't clock the wording of the comment you responded to</p></div></div></div></div></div><div class="e l2" id="t1_ipo56x5"><header><a href="https://www.reddit.com/u/darrellbear">darrellbear</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipo56x5/">Sat 2022-09-24 at 02:09</a> (1, edited) <a href="#t1_ipn6mmm" class="n P">▣</a> <a href="#t1_ipo363i" class="n A">🠉</a> <a href="#t1_ipoz574" class="n B">🠋</a> <a href="#t1_ipo56x5" class="n S">◯</a></header><p>'Planet' means "wanderer". It goes way back in time, when night watches were stood for security, shamans watched too. You watch the sky every night, you notice the changes, you see the cycles of the seasons and the stars changing with them. You start putting your culture's stories in the sky, and you notice the wanderers, and weave them into your stories, gods, heroes and such that myths are made of. The instant I first saw the carvings at Gobleki Tepe, the scorpion and such, I thought of depictions of the sky. The Scorpion is an ancient constellation.</p><div class="o l3" id="t1_ipobwzf"><header><a href="https://www.reddit.com/u/ZacQuicksilver">ZacQuicksilver</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipobwzf/">Sat 2022-09-24 at 03:10</a> (1) <a href="#t1_ipo56x5" class="n P">▣</a> <a href="#" class="n A D">🠉</a> <a href="#" class="n B D">🠋</a> <a href="#t1_ipobwzf" class="n S">◯</a></header><p>This.</p></p><p><p>The original seven planets were the seven objects that you can see with the naked eye and move against the backdrop of the stars in predictable ways: Saturn, Jupiter, Mars, Venus, Mercury, Sun, and Moon. Asteroids and comets also move against the backdrop of the stars, but aren't predictable.</p></div></div><div class="e l2" id="t1_ipoz574"><header><a href="https://www.reddit.com/u/1st-time-on-reddit">1st-time-on-reddit</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipoz574/">Sat 2022-09-24 at 07:44</a> (1) <a href="#t1_ipn6mmm" class="n P">▣</a> <a href="#t1_ipo56x5" class="n A">🠉</a> <a href="#" class="n B D">🠋</a> <a href="#t1_ipoz574" class="n S">◯</a></header><p>Please tell me more about they, seems like you’ve been here awhile and know much more than everyone else</p></div></div><div class="f o l1" id="t1_ipni4ag"><header><a href="https://www.reddit.com/u/Kiiaru">Kiiaru</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipni4ag/">Fri 2022-09-23 at 22:54</a> (1) <a href="#t3_xm9kun" class="n P">▣</a> <a href="#t1_ipn6mmm" class="n A">🠉</a> <a href="#t1_ipnq3wp" class="n B">🠋</a> <a href="#t1_ipni4ag" class="n S">◯</a></header><p>When you look up at the night sky, you give it a casual glance at best, and you look for a few moments and then go back inside or walk somewhere else.</p></p><p><p>Hundreds of years ago, they stared at stars for hours and noticed which ones twinkled differently and moved around over the course of days/weeks/months. You and I don't notice that because we're just not looking for it.</p></div><div class="f o l1" id="t1_ipnq3wp"><header><a href="https://www.reddit.com/u/Tanagrabelle">Tanagrabelle</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipnq3wp/">Sat 2022-09-24 at 00:00</a> (1, edited) <a href="#t3_xm9kun" class="n P">▣</a> <a href="#t1_ipni4ag" class="n A">🠉</a> <a href="#t1_ipnyqa3" class="n B">🠋</a> <a href="#t1_ipnq3wp" class="n S">◯</a></header><p>It’s a little hard to stay in ELI5 territory. But as far as they know,1800 BC the Babylonians were already maintaining daily, monthly, and yearly records of the perceived motion of the sun and moon, and other celestial bodies. Pythagoras of Greece, born around 570 BC,mathematically determined the world was round, and realized so were most other celestial bodies. Eratosthenes of Greece (sp?) used math to calculate the circumference of Earth, the tilt of the axis, and even thought up leap days. He was born around 276 BC. Aryabhata of India,born maybe 476 AD, figured out eclipses, figured out the moon reflected the light of the sun, the value of pi to four places, all kinds of mathematics that I need ELI5. Mayan calendar, Egyptian calendar very like the one we use now; look up Nabta Playa, it’s really cool! (A lot of what I’m typing involves a battle with the bloody auto correct!!) Gan De, Chinese astronomer about four centuries before Christ, created the Star Catalogue of Sho. Persian astronomer Abd al-Rahman al-Sufi born 903 AD, discovered the Andromeda galaxy. Abu Mahmud Hamid ibn al-Kidhr al-Khojandi built an enormous mural sextant and figured out the axial tilt so well he even noted that it was decreasing. Look up those mural sextants, they’re slightly mind-boggling. (edited for typos and disappearing spaces between words.)</p></div><div class="f o l1" id="t1_ipnyqa3"><header><a href="https://www.reddit.com/u/los-gokillas">los-gokillas</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipnyqa3/">Sat 2022-09-24 at 01:13</a> (1) <a href="#t3_xm9kun" class="n P">▣</a> <a href="#t1_ipnq3wp" class="n A">🠉</a> <a href="#t1_ipn5y1x" class="n B">🠋</a> <a href="#t1_ipnyqa3" class="n S">◯</a></header><p>Yeah but we don't really look at the stars nowadays. Before light pollution, reading, TV, radio, etc. Humans had stars at night. Not only did they stare at them long enough to recognize that some were different, planets, but they also knew what certain stars meant, for them. When one constellation was in one spot of the sky there was water at this site. When a constellation was in a different spot buffalo could be found at another site</p></div><div class="f o l1" id="t1_ipn5y1x"><header><a href="https://www.reddit.com/u/drafterman">drafterman</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipn5y1x/">Fri 2022-09-23 at 21:21</a> (1) <a href="#t3_xm9kun" class="n P">▣</a> <a href="#t1_ipnyqa3" class="n A">🠉</a> <a href="#t1_ipo2ybd" class="n B">🠋</a> <a href="#t1_ipn5y1x" class="n S">◯</a></header><p>Because planets. That's literally what "planet" means: "wanderer." If you sat and watched, you'd noticed that some of those dots move perceptibly across the sky while others remain fixed.</p><div class="p l2" id="t1_ipn64ee"><header><a href="https://www.reddit.com/u/Maggo6452">Maggo6452</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipn64ee/">Fri 2022-09-23 at 21:22</a> (1) <a href="#t1_ipn5y1x" class="n P">▣</a> <a href="#" class="n A D">🠉</a> <a href="#" class="n B D">🠋</a> <a href="#t1_ipn64ee" class="n S">◯</a></header><p>Does this mean they didn’t discover the difference between stars but they discovered there are yellow dots that are fixed and yellow dots that move slowly?</p><div class="o l3" id="t1_ipn83pj"><header><a href="https://www.reddit.com/u/alvenestthol">alvenestthol</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipn83pj/">Fri 2022-09-23 at 21:37</a> (1) <a href="#t1_ipn64ee" class="n P">▣</a> <a href="#" class="n A D">🠉</a> <a href="#t1_ipn7j56" class="n B">🠋</a> <a href="#t1_ipn83pj" class="n S">◯</a></header><p>Before telescopes, people had no idea whatsoever what stars even were, much less what made planets and stars move in different ways - so yeah, all they discovered were that some stars tend to wander, while others moved together.</p></div><div class="o l3" id="t1_ipn7j56"><header><a href="https://www.reddit.com/u/Target880">Target880</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipn7j56/">Fri 2022-09-23 at 21:33</a> (1, edited) <a href="#t1_ipn64ee" class="n P">▣</a> <a href="#t1_ipn83pj" class="n A">🠉</a> <a href="#t1_ipnrtny" class="n B">🠋</a> <a href="#t1_ipn7j56" class="n S">◯</a></header><p>Yes, that is exactly what was done. The planes that was known about since ancient times are easy to see and move a lot of relative stars far away. </p></p><p><p>At maximum brightness, the object in the sky in order are the sun, Moon, Venus, Jupiter, Mars, Mercury ,star system Sirius, star Canopus, and Saturn. So all planets known about hundred of years ago are in the top 10 brightest objects in the sky. If you use planest as the ancient greek did the sun and moon are included but not earth</p></p><p><p>So we it is not a few dim stars amone other that move in the sky, it is the brightest object in the sky that are the one moving. </p></p><p><p>They are also all close to a single line in the sky because all orbit in proximally the same plane areound the sun. The moon and sun are alos around the same plane.</p></p><p><p>Take a look at https://stellarium-web.org/ and move the time forward to see where stars are relative to each other and when they are visible in the sky for you. You need to set it to your location if is not done correctly automatic. Use an app like googles Sky Map and go out and look at the plates. They are simple to see because they are very bright</p></p><p><p>It is not a case that they were discovered just hundreds of years ago but thousands of years ago. I would guess that it is not modern humans that did the discovery but an evolutionary ancestor to us.</p></p><p><p>If you do not live in an age with lots of artificial light like we do the start in the sky will be a lot more familiar to you.</p></div><div class="o l3" id="t1_ipnrtny"><header><a href="https://www.reddit.com/u/flamableozone">flamableozone</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipnrtny/">Sat 2022-09-24 at 00:15</a> (1) <a href="#t1_ipn64ee" class="n P">▣</a> <a href="#t1_ipn7j56" class="n A">🠉</a> <a href="#t1_ipojrwq" class="n B">🠋</a> <a href="#t1_ipnrtny" class="n S">◯</a></header><p>Unrelated, but stars - and planets - have different colors. It's not always easy to tell, but there are reds and blues and yellows and oranges. It's a lot easier to see once you've learned what to look for, but the ancients who didn't have to fight light pollution definitely wouldn't have seen everything as the same color!</p></div><div class="o l3" id="t1_ipojrwq"><header><a href="https://www.reddit.com/u/evanamd">evanamd</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipojrwq/">Sat 2022-09-24 at 04:30</a> (1) <a href="#t1_ipn64ee" class="n P">▣</a> <a href="#t1_ipnrtny" class="n A">🠉</a> <a href="#" class="n B D">🠋</a> <a href="#t1_ipojrwq" class="n S">◯</a></header><p>They actually move surprisingly fast. I tend to walk in a southward direction home from work in the winter. This past winter, I would always see two very bright stars in a slight offset from each other (Jupiter and Saturn), and one that looked more red than the others (Mars). Over the course of only a few hours, they went from halfway up the sky, to barely above the horizon, and in slightly different directions</p></p><p><p>In that same time, the constellations around them (like Orion) covered barely half that distance, but always in the exact same direction. </p></p><p><p>When you’re slightly bored, like I was on my walks home, it’s easy to pick out the brightest spots in the sky and draw shapes. When you do it say after day you notice the shapes changing, and the starting positions of the planets change a lot faster than the starting points of the constellations. Iirc over the course of one week, Jupiter’s starting point on my walk moved by about 3 thumb-widths. Orion’s starting point hadn’t moved enough to notice</p></div></div></div><div class="f o l1" id="t1_ipo2ybd"><header><a href="https://www.reddit.com/u/EatShitLeftWing">EatShitLeftWing</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipo2ybd/">Sat 2022-09-24 at 01:49</a> (1) <a href="#t3_xm9kun" class="n P">▣</a> <a href="#t1_ipn5y1x" class="n A">🠉</a> <a href="#t1_ipn6spz" class="n B">🠋</a> <a href="#t1_ipo2ybd" class="n S">◯</a></header><p>Because planets have "retrograde" motion. Stars consistently move from east to west in the sky (keeping track of them over multiple days). Planets also generally move from east to west, but will have periods of time that they instead appear to move from west to east.</p></p><p><p>Eventually we figured out that it's because the sun is the center of the solar system, and when a planet appears to be moving in "retrograde", that is really when Earth, in its orbit, is moving past that other planet, in its orbit.</p></div><div class="f o l1" id="t1_ipn6spz"><header><a href="https://www.reddit.com/u/phiwong">phiwong</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipn6spz/">Fri 2022-09-23 at 21:27</a> (1) <a href="#t3_xm9kun" class="n P">▣</a> <a href="#t1_ipo2ybd" class="n A">🠉</a> <a href="#t1_ipnjq46" class="n B">🠋</a> <a href="#t1_ipn6spz" class="n S">◯</a></header><p>The motion of a planet in the sky is very different from that of stars. This will not be obvious by just viewing one night unfortunately. By tracking the motion of the brightest dots in the sky over a period, it becomes clear that certain objects (planets) move very differently than the others (stars). </p></p><p><p>The telescope was discovered (at least in the western world) in the 1600s. With even a simple telescope it is pretty clear that these objects are not stars.</p></div><div class="f o l1" id="t1_ipnjq46"><header><a href="https://www.reddit.com/u/Cheap_Improvement19">Cheap_Improvement19</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipnjq46/">Fri 2022-09-23 at 23:07</a> (1) <a href="#t3_xm9kun" class="n P">▣</a> <a href="#t1_ipn6spz" class="n A">🠉</a> <a href="#t1_ipnk3y3" class="n B">🠋</a> <a href="#t1_ipnjq46" class="n S">◯</a></header><p>Mars could be seen with the naked eye, but the invention of telescopes really pushed the field forward. </p></p><p><p>Telescopes required (at the time) complex glass production. As a result planetary discovery heavily relied on a large established glass industry that could make the types of specialized curved lenses the teslescopes required. This limited astronomy to some parts of the world only. Chemistry entirely relied on glass as well and also ended up a geographically limited scientific field, but that's a different topic.</p></div><div class="f o l1" id="t1_ipnk3y3"><header><a href="https://www.reddit.com/u/thejerkstorekalled">thejerkstorekalled</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipnk3y3/">Fri 2022-09-23 at 23:10</a> (1) <a href="#t3_xm9kun" class="n P">▣</a> <a href="#t1_ipnjq46" class="n A">🠉</a> <a href="#t1_ipnofri" class="n B">🠋</a> <a href="#t1_ipnk3y3" class="n S">◯</a></header><p>Planets not only move differently than stars, but they more or less move in the same plane as the sun and the moon</p></div><div class="f o l1" id="t1_ipnofri"><header><a href="https://www.reddit.com/u/jaa101">jaa101</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipnofri/">Fri 2022-09-23 at 23:46</a> (1) <a href="#t3_xm9kun" class="n P">▣</a> <a href="#t1_ipnk3y3" class="n A">🠉</a> <a href="#t1_ipo318s" class="n B">🠋</a> <a href="#t1_ipnofri" class="n S">◯</a></header><p>The planets are extremely bright. Of the five known to the ancients, all of them except Saturn can appear brighter than any star other than the sun. If you're regularly outside at night they're all very conspicuous.</p></div><div class="f o l1" id="t1_ipo318s"><header><a href="https://www.reddit.com/u/YCityJim">YCityJim</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipo318s/">Sat 2022-09-24 at 01:50</a> (1) <a href="#t3_xm9kun" class="n P">▣</a> <a href="#t1_ipnofri" class="n A">🠉</a> <a href="#t1_ipo3v4z" class="n B">🠋</a> <a href="#t1_ipo318s" class="n S">◯</a></header><p>Well, it was hundreds of years ago and there was little to do. It was dark since light pollution was hundreds of years away. Copernicus and Kepler tracked movements and noticed that some of the ”stars” had unusual movements.</p></div><div class="f o l1" id="t1_ipo3v4z"><header><a href="https://www.reddit.com/u/86tuning">86tuning</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipo3v4z/">Sat 2022-09-24 at 01:57</a> (1) <a href="#t3_xm9kun" class="n P">▣</a> <a href="#t1_ipo318s" class="n A">🠉</a> <a href="#t1_ipo599v" class="n B">🠋</a> <a href="#t1_ipo3v4z" class="n S">◯</a></header><p>planet means "wanderer" </p></p><p><p>stars essentially have fixed positions in the sky, but planets move. when you see Venus (the morning star or evening star) you'll note it's position changes throughout the year because it's moving. </p></p><p><p>stars, OTOH are so far away they are essentially stationary.</p></div><div class="f o l1" id="t1_ipo599v"><header><a href="https://www.reddit.com/u/FellowConspirator">FellowConspirator</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipo599v/">Sat 2022-09-24 at 02:10</a> (1) <a href="#t3_xm9kun" class="n P">▣</a> <a href="#t1_ipo3v4z" class="n A">🠉</a> <a href="#t1_ipodo00" class="n B">🠋</a> <a href="#t1_ipo599v" class="n S">◯</a></header><p>The night sky was very dark, except for the stars and planets, so on clear nights they’d spend a lot of time looking at the patters of stars in the sky.</p></p><p><p>They played connect-the-dots to find shapes that they could easily recognize: constellations. That made it easy to follow where the stars were in the sky and even give names to some of them.</p></p><p><p>They noticed that constellations moved up and down in the sky with the seasons, but the positions of the stars in a constellation, and constellations relative to one another, stayed the same. Except…</p></p><p><p>There were a small number of bright stars in the sky whose positions moved about — in one constellation one day, then moving to another in a few days or weeks. They weren’t part of constellations, but “wanderers” (or in Greek, “planētēs”). They didn’t know what stars or planets were other than lights in the heavens, but “planets” were wandering lights in the heavens.</p></div><div class="f o l1" id="t1_ipodo00"><header><a href="https://www.reddit.com/u/SSCharles">SSCharles</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipodo00/">Sat 2022-09-24 at 03:27</a> (1) <a href="#t3_xm9kun" class="n P">▣</a> <a href="#t1_ipo599v" class="n A">🠉</a> <a href="#t1_ipogcbu" class="n B">🠋</a> <a href="#t1_ipodo00" class="n S">◯</a></header><p>As you get older you notice long term patterns, you can see the moon moving, notice stations, etc. I'm sure with nothing else to do you would get use to the sky and notice one of the "stars" moves around over time.</p></div><div class="f o l1" id="t1_ipogcbu"><header><a href="https://www.reddit.com/u/zachtheperson">zachtheperson</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipogcbu/">Sat 2022-09-24 at 03:53</a> (1) <a href="#t3_xm9kun" class="n P">▣</a> <a href="#t1_ipodo00" class="n A">🠉</a> <a href="#t1_ipolx8k" class="n B">🠋</a> <a href="#t1_ipogcbu" class="n S">◯</a></header><p>Stars more or less move all at once. Someone looking at the sky over time could notice some stars seemingly moving in separate directions to the rest of stars that also happened to appear brighter. Eventually they realized these things were separate bodies orbiting the sun.</p></p><p><p>This Wikipedia page is pretty cool, as it not only goes over the history of when they were discovered, but even mentions what the astronomers saw that tipped them off in the first place: <a href="https://en.wikipedia.org/wiki/Timeline_of_discovery_of_Solar_System_planets_and_their_moons">https://en.wikipedia.org/wiki/Timeline_of_discovery_of_Solar_System_planets_and_their_moons</a></p></div><div class="f o l1" id="t1_ipolx8k"><header><a href="https://www.reddit.com/u/DMsWorkshop">DMsWorkshop</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipolx8k/">Sat 2022-09-24 at 04:54</a> (1) <a href="#t3_xm9kun" class="n P">▣</a> <a href="#t1_ipogcbu" class="n A">🠉</a> <a href="#t1_ipomaco" class="n B">🠋</a> <a href="#t1_ipolx8k" class="n S">◯</a></header><p>Observing celestial phenomena was vitally important for early cultures. It wasn't just a hobby, it helped them to keep track of the passage of time and therefore how to plan for the future. There's a reason why so many ancient religious ceremonies are timed for certain celestial phenomena; that was the basis of their calendar. </p></p><p><p>So, of course, any culture that uses the stars as a way to plan their lives will get to learn familiar constellations and categorize the brightest stars. And that's what the planets originally were to them: stars. Specifically, stars that wandered. They didn't stay in their constellations, they moved around the sky. Thus, the Greeks called them planets, which came from the same root as their word for 'wanderer'.</p></div><div class="f o l1" id="t1_ipomaco"><header><a href="https://www.reddit.com/u/trutheality">trutheality</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipomaco/">Sat 2022-09-24 at 04:58</a> (1) <a href="#t3_xm9kun" class="n P">▣</a> <a href="#t1_ipolx8k" class="n A">🠉</a> <a href="#t1_ipooybg" class="n B">🠋</a> <a href="#t1_ipomaco" class="n S">◯</a></header><p>They didn't know they were closer. What they did notice is that almost all the dots in the sky stayed in the same positions relative to each other and the sun. Almost all.<br>A select few dots changed positions relative to everything else from day to day. Those moving dots are the planets (the word "planet" has it's origins in a Greek word for "drifting").</p></div><div class="f o l1" id="t1_ipooybg"><header><a href="https://www.reddit.com/u/Omphalopsychian">Omphalopsychian</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipooybg/">Sat 2022-09-24 at 05:29</a> (1) <a href="#t3_xm9kun" class="n P">▣</a> <a href="#t1_ipomaco" class="n A">🠉</a> <a href="#t1_ipop1ds" class="n B">🠋</a> <a href="#t1_ipooybg" class="n S">◯</a></header><p>Go outside tonight. Find the 3 brightest stars. Mentally note roughly where they are at that time of night. Repeat once a week. You will discover some planets.</p></p><p><p>Mercury is tough to spot unless you live on the ocean, because it's only visible close to the horizon. Jupiter, Mars, and Venus are <em>bright</em>. You will find them. Once you've found those, Saturn is pretty easy too. They all travel in the same arc across the sky.</p></div><div class="f o l1" id="t1_ipop1ds"><header><a href="https://www.reddit.com/u/t3hPoundcake">t3hPoundcake</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipop1ds/">Sat 2022-09-24 at 05:30</a> (1) <a href="#t3_xm9kun" class="n P">▣</a> <a href="#t1_ipooybg" class="n A">🠉</a> <a href="#t1_ipoq6of" class="n B">🠋</a> <a href="#t1_ipop1ds" class="n S">◯</a></header><p>People like exploring things. I don't know all the history but let's skip to the part where someone has a telescope for looking out into the coast waters and spotting possible enemy ships or trade ships. One day the moon is big and bright and that person goes "Well fuck let me look at this mf with this thing he'll yeah brother" and even with a very weak telescope you can see tons of detail in the moon. Try it if you haven't.</p></p><p><p>So at the same time people were also just looking at the stars and noticing that some of them were always in the same spot, some were just very so slightly moved a little bit, and other ones were moving a great deal just over the course of one night or a few days or a week. Some of them weren't even visible anymore. Because of the Earth's rotation or something fancy like that.</p></p><p><p>So now these people take their telescopes and keep looking up and they record what they see, these dots and patterns and how they move.</p></p><p><p>Then one nice clear night someone looks up and sees not a white dot but a ball. A ball with colors and...clouds? Rings? Surface features? What the fuck are these things? Planets. Fucking planets.</p></p><p><p>It's also important to remember that back when these things were first being discovered, light polution was basically non-existent. You could see the bright bands of billions of stars of the Milky Way with your naked eyes. Today you have be in the absolute darkest parts of the world and as elevated as you can possibly be to see these things.</p></p><p><p>There was zero chance people didn't notice these things in detail with their naked eyes, which is what prompted them to look closer using the tools that they developed for other things (telescopes).</p></div><div class="f o l1" id="t1_ipoq6of"><header><a href="https://www.reddit.com/u/CherryDudeFellaGirl">CherryDudeFellaGirl</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipoq6of/">Sat 2022-09-24 at 05:45</a> (1) <a href="#t3_xm9kun" class="n P">▣</a> <a href="#t1_ipop1ds" class="n A">🠉</a> <a href="#t1_ipoqriq" class="n B">🠋</a> <a href="#t1_ipoq6of" class="n S">◯</a></header><p>Haha i love light pollution so much, im so glad to be born mid into the proliferation of massive light pollution</p></div><div class="f o l1" id="t1_ipoqriq"><header><a href="https://www.reddit.com/u/miemcc">miemcc</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipoqriq/">Sat 2022-09-24 at 05:52</a> (1) <a href="#t3_xm9kun" class="n P">▣</a> <a href="#t1_ipoq6of" class="n A">🠉</a> <a href="#t1_ipp49lp" class="n B">🠋</a> <a href="#t1_ipoqriq" class="n S">◯</a></header><p>How they moved in the sky was 'odd'. Occasionally they would appear to move the 'wrong' way.</p></p><p><p>Both the Earth and the planet are orbiting the Sun. So sometimes we would 'catch up compared to the planet and other times we would appear to 'fall back. So planets would appear to move one way for part of the year and then appear to move the 'wrong' way for other periods</p></p><p><p>Think of runners on a race track. One on the inside line going quite fast and one on the outside line, plodding along. Sometimes it seems that the direct distance between them is closing, but then other times they are moving apart</p></p><p><p>The name planets derives from a Greek word planḗtai, meaning wanderers. This was due to this odd looping behavior in the observed sky.</p></div><div class="f o l1" id="t1_ipp49lp"><header><a href="https://www.reddit.com/u/texxelate">texxelate</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipp49lp/">Sat 2022-09-24 at 08:58</a> (1) <a href="#t3_xm9kun" class="n P">▣</a> <a href="#t1_ipoqriq" class="n A">🠉</a> <a href="#t1_ipp8r92" class="n B">🠋</a> <a href="#t1_ipp49lp" class="n S">◯</a></header><p>It boils down to curiosity. For an example of this, google Galileo Jupiter Moons. </p></p><p><p>In the early 1600s he persistently pointed his telescope at specific “stars” and noticed some of them moving. He noticed a pattern wherein some of them seemed to disappear and reappear on the other side, eventually hypothesising they were orbiting the larger one. Keep in mind this was before “the larger one” was known as Jupiter or even a planet. </p></p><p><p>To come to such conclusions when all you have is your mind and (relatively) crude tools, curiosity and genius.</p></div><div class="f o l1" id="t1_ipp8r92"><header><a href="https://www.reddit.com/u/turnedonbyadime">turnedonbyadime</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipp8r92/">Sat 2022-09-24 at 10:04</a> (1) <a href="#t3_xm9kun" class="n P">▣</a> <a href="#t1_ipp49lp" class="n A">🠉</a> <a href="#t1_ippb6b8" class="n B">🠋</a> <a href="#t1_ipp8r92" class="n S">◯</a></header><p>Go work the night shift at an outdoor job. You will quickly notice that every star is not just a star. People spent much more time outside and in darkness in ancient times than we do, so they had plenty of opportunity to observe the differences in the night sky.</p></div><div class="f o l1" id="t1_ippb6b8"><header><a href="https://www.reddit.com/u/bunnylo">bunnylo</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ippb6b8/">Sat 2022-09-24 at 10:39</a> (1) <a href="#t3_xm9kun" class="n P">▣</a> <a href="#t1_ipp8r92" class="n A">🠉</a> <a href="#t1_ippc1k3" class="n B">🠋</a> <a href="#t1_ippb6b8" class="n S">◯</a></header><p>even with the naked eye, there is a noticeable difference between stars and planets: stars twinkle, planets don’t.</p><div class="e l2" id="t1_ippg9a3"><header><a href="https://www.reddit.com/u/floating__point">floating__point</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ippg9a3/">Sat 2022-09-24 at 11:42</a> (1) <a href="#t1_ippb6b8" class="n P">▣</a> <a href="#" class="n A D">🠉</a> <a href="#" class="n B D">🠋</a> <a href="#t1_ippg9a3" class="n S">◯</a></header><p>Indeed, because planets reflect sun's light and stars emit their own.</p></div></div><div class="f o l1" id="t1_ippc1k3"><header><a href="https://www.reddit.com/u/Farnsworthson">Farnsworthson</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ippc1k3/">Sat 2022-09-24 at 10:50</a> (1, edited) <a href="#t3_xm9kun" class="n P">▣</a> <a href="#t1_ippb6b8" class="n A">🠉</a> <a href="#t1_ipncn5c" class="n B">🠋</a> <a href="#t1_ippc1k3" class="n S">◯</a></header><p>The clue is in the name. "Planet" means "wanderer". Because that's what planets do - they wander.</p></p><p><p>People used to be able to see the night sky much better than most of us can nowadays (courtesy of light polution). And some of them paid close attention, and got to know the sky well, not least because it's massively useful knowledge - you can navigate by the stars. And if you watch the sky over days, weeks, months, years, you notice that some of the lights move about. Those are the planets. The actual (so-called "fixed") stars don't (or at least, not on any timescale that indivduals are able to experience).</p></div><div class="f o l1" id="t1_ipncn5c"><header><a href="https://www.reddit.com/u/frakc">frakc</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipncn5c/">Fri 2022-09-23 at 22:11</a> (1) <a href="#t3_xm9kun" class="n P">▣</a> <a href="#t1_ippc1k3" class="n A">🠉</a> <a href="#" class="n B D">🠋</a> <a href="#t1_ipncn5c" class="n S">◯</a></header><p>Planet means wanderer. </p></p><p><p>After people discovered that position of the moon is corelated with hightides and sun brightness more or less indecated season they started to lookat stars and note position of them and found some of them moves.</p></p><p><p>Thus they found furst planets:<br>Moon, Sun, Mercury, Venus, Mars, Saturn, Jupiter (in that order)</p></p><p><p>Until late 16 century no other planets were discovered. </p></p><p><p>Also discovery of each planet leaded to immense impact on culture and technology.</p></p><p><p>2 most significant to make thing short:</p></p><p><p>Jupiter year is equal to 12 Earth years. Thus ancient people got calendar and ability to track seasons. From thet point agreculture turned from random event to technology allowing rise of countries as problems with food became less severe.</p></p><p><p>Mars is most reddest and biggest (every few ears) on the end of october, when storrages are full of provussion and supplies prepared for winter. Best time for some pillage.</p></p><p><p>It also is very big but not so red on start if march. Time when all food is mostly consumed, but now storages are full of different crafts which were made during winter. Also wery good time for pillage </p></p><p><p>Thus in almost every culture which discovered astrology Mars is associated with god of war.</p><div class="e l2" id="t1_ipnht4p"><header><a href="https://www.reddit.com/u/Antithesys">Antithesys</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipnht4p/">Fri 2022-09-23 at 22:52</a> (1) <a href="#t1_ipncn5c" class="n P">▣</a> <a href="#" class="n A D">🠉</a> <a href="#" class="n B D">🠋</a> <a href="#t1_ipnht4p" class="n S">◯</a></header><p>> Thus they found furst planets: Moon, Sun, Mercury, Venus, Mars, Saturn, Jupiter (in that order)</p></p><p><p>I'm curious how you know they were discovered "in that order" when all of them would have been obvious. I'm dubious that Jupiter would have been the last planet discovered by ancient people since it's one of the brightest objects in the sky.</p></p><p><p>> Until late 16 century no other planets were discovered. </p></p><p><p>Which planet was discovered in the late 16th century? Uranus was discovered in 1781, with Neptune, Ceres and Pluto all coming after that.</p></p><p><p>> Jupiter year is equal to 12 Earth years. Thus ancient people got calendar and ability to track seasons.</p></p><p><p>I'm not aware of any connection between Jupiter and the development of a calendar. It certainly isn't useful to track seasons on Earth, especially not compared to stars.</p></p><p><p>> Mars is most reddest and biggest (every few ears) on the end of october...It also is very big but not so red on start if march.</p></p><p><p>Mars' orbit does not coincide with Earth's calendar <em>at all.</em> It's at opposition every 25-26 months, which means its closest approach drifts down the calendar fairly rapidly.</p><div class="o l3" id="t1_ipnsu6j"><header><a href="https://www.reddit.com/u/frakc">frakc</a>, on <a href="https://www.reddit.com/r/explainlikeimfive/comments/xm9kun/eli5_how_did_the_people_hundreds_of_years_ago/ipnsu6j/">Sat 2022-09-24 at 00:23</a> (1) <a href="#t1_ipnht4p" class="n P">▣</a> <a href="#" class="n A D">🠉</a> <a href="#" class="n B D">🠋</a> <a href="#t1_ipnsu6j" class="n S">◯</a></header><p>>I'm curious how you know they were discovered "in that order"</p></p><p><p>The Earliest Sumerian predictions did not mention Jupiter, they operated with 6 planets. </p></p><p><p>>Which planet was discovered in the late 16th century</p></p><p><p>I took the date earlier to not google the exact discovery date. 1781 still goes after the 16th century. </p></p><p><p>>I'm not aware of any connection between Jupiter and the development of a calendar.</p></p><p><p><em>Jupiter in house Pisces, Mars in taurus, Venus in leo</em> - gives date precise up to a month (September 2022). Adding the other 4 planets with directions gave a date precise up to a week. It is not hard to track the year and season with that system. The Ancient Sumerian prediction was nothing more than the calendar with dates for planting seeds. Then it grew with mythology and beliefs to predict the future of the country. </p></p><p><p>>Mars' orbit does not coincide with Earth's calendar at all </p></p><p><p>Yes and no. Mars is observed red color when Earth is "between" Sun and Mars. As mars year is almost twice bigger as earth year, that happens roughly every year and a half. Now goes fun with ecliptic and light dispersion. While it can be red at any point of year, the biggest and the reddes situation happens on autumn with span 1.2-8 years. Thus every few years.</p><script>function checkKey(e){"38"==(e=e||window.event).keyCode?(e.preventDefault(),scrollToSibling("A")):"40"==e.keyCode?(e.preventDefault(),scrollToSibling("B")):"37"!=e.keyCode&&"80"!=e.keyCode||scrollToParent()}function scrollToSibling(e){var o,t=window.location.hash.substr(1),n=document.getElementById(t).getElementsByClassName(e)[0];n.classList.contains("D")||(o=n.getAttribute("href").substr(1),document.getElementById(o).scrollIntoView(!0),window.location.hash=o)}function scrollToParent(){var e=window.location.hash.substr(1);document.getElementById(e).parentNode.id.scrollIntoView(!0),window.location.hash=target_id}document.onkeydown=checkKey;</script>