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  • Looking up the night sky on a clear night, you can see anywhere from a few hundred stars

  • to a few thousand without a telescope.

  • This massive dome of speckled darkness has been a giant game of connect the dots for

  • millennia.

  • These constellations have represented the gods, the changing of the seasons, and the

  • passage of time.

  • They even show up in our horoscopes.

  • These of course, are the constellations in the Zodiac, and to be specific,

  • these are 12 constellations that have held immense significance

  • throughout history.

  • And while they don't determine our personalities or fates, they do play an important role in astronomy

  • and understanding how Earth moves through space.

  • Before we dive into the role of zodiacs in astronomy.

  • Let's first clear up a few things about astrology.

  • It's not hard to imagine why ancient people placed a lot of value on certain constellations.

  • Finding relationships between the movement of the stars and what was happening on Earth,

  • likely helped make their world easier to predict and understand.

  • For the Babylonians the shape of a ram in the night sky meant spring was finally around

  • the corner, and the Mayans may have tracked the movement of the planets and constellations

  • in their detailed calendars.

  • You may be asking yourself, why are we talking about the zodiacs in a science video.

  • Well, actually the reason why they stood out among the rest to ancient stargazers is kind

  • of the same reason why they're pretty important for understanding basic astronomy today.

  • Here's how it works.

  • If you could see all of the stars during the day.

  • Over the course of a year, you'd be able to see the sun, slowly moving along a path from

  • one constellation to the next.

  • That imaginary path is called the ecliptic.

  • And it's arguably one of the most important coordinate systems in astronomy.

  • What makes the ecliptic line so useful is how it shows the plane of Earth's orbit around

  • the sun.

  • And our place in the solar system, because all of the major celestial bodies in the solar

  • system orbit the sun in a similar way.

  • They're on or near the same flat plane of the ecliptic.

  • That's all of the planets, and even the moon. While some differ by a few degrees from the line.

  • They're all essentially there.

  • Another reason Zodiac constellations became so famous throughout history, is that we always

  • see the moon planets and eclipses near them.

  • Eclipse... ecliptic.

  • You get the idea.

  • With all this action in one area of the night sky, it's easy to understand why ancient interpreters

  • placed immense value on these constellations, but it's also really important for modern

  • space work.

  • And it also turned out to be a good place to hunt for exoplanets during NASA's K2

  • mission, the Kepler mission was a space telescope that search for exoplanets by measuring brightness

  • dips in nearby stars.

  • And although the Kepler mission wasn't originally designed to search the ecliptic.

  • That part of the sky ended up being a good place to find exoplanets.

  • The whole purpose of Kepler was to find planets around other stars.

  • So originally we pointed Kepler near the constellation of Cygnus, and we picked that part of the

  • sky because we didn't know how common planets were.

  • But about four years into the mission, two wheels on the spacecraft failed, meaning

  • that it could no longer hold steady enough to observe near Cygnus, so they got creative and used the sun to keep

  • the telescope pointed in the same place.

  • Because the Kepler Space Telescope had symmetrical solar panels, the solar pressure was enough to keep it

  • oriented in one direction, and with the sun pushing it slightly, it meant that K2 was now pointed

  • directly at the ecliptic line.

  • But that was still great, we still found, oh, over 400 planets, looking at all these different parts of the sky

  • every few days. Some of us who work on K2 we think of the K2 mission as what may be one of NASA's

  • best hacks.

  • While astronomers continue to use the ecliptic line to learn about our solar system and exoplanets in the galaxy,

  • there's so much you can see right from where you are.

  • Depending on where you live, you should be able to see at least one Zodiac constellation every single night.

  • And my favorite part is that it's easy to find the planets, once you know where to look,

  • they're always going to be along the ecliptic.

  • It's pretty cool to be able to see where you are, relative to the rest of the solar system,

  • right from your backyard.

  • And one more thing that astrology doesn't get quite right when it comes to the Zodiac

  • constellations... astrology assumes that the zodiac signs are split evenly into the 12

  • slices of the year.

  • But in fact, the sun spends wildly different lengths of time in each Zodiac constellation.

  • Not to mention Ohiuchus, a 13th constellation, known as the serpent bearer, in which the

  • sun spends 18 days.

  • My name is Sarafina Nance, and this is Seeker Constellations.

  • If there's an astronomy topic or a favorite constellation you want us to cover.

  • Let us know in the comments.

  • Thanks for watching.

Looking up the night sky on a clear night, you can see anywhere from a few hundred stars

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Here’s Why Zodiac Constellations Are Still Used in Astronomy

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    林宜悉 posted on 2021/01/15
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