Word of the Week: Ecliptic!

Hey, Sky Fans!

These days are a great time to be watching the skies, aren’t they? Old stars going, new ones on their way in. For the first time in a while, we have the two biggest planets, the two most distant naked eye objects in our solar system, in the sky at once.

Last weekend, we had the Moon to help us out, but Jupiter’s been well-placed for lookin’ at, in the southeast by the time darkness falls, for some time. Saturn, meanwhile, joins the mix in the east a couple of hours later. By about 10:30 or so, you’ve got a good shot at seeing them both. They’re separated by a big chunk of sky, but it’s still quite a sight to see. This Friday, June 9, the Full Moon will be close to Saturn all night.

As June goes on, they’ll tighten up a bunch, but not quite meet up. This might be a great time to grab a friend or two and do some planet hunting.

You know, I didn’t feel like doing a Word of the Week this week, but… I can’t say no to you.


Actually, I realized the other day that I hadn’t done a Word of the Week for this one yet. I’m as surprised as you are. This is an important one.

If you could get all of the planets in the sky at the same time, as we did in the mornings a year or so ago, you’d see they all draw an easy line from horizon to horizon. When the Sun rises, you’d see the path it takes each day is along that same line.

This imaginary line, the apparent path the Sun takes across the sky, is called the ecliptic.

Word of the Week: Ecliptic!
Word of the Week: Ecliptic!

All of the major planets, Earth included, orbit the Sun in more or less the same plane. If we could watch the solar system go by from millions of miles above the Earth’s north pole, we’d see everything zipping around the Sun counterclockwise, like marbles rolling around a dish. Actually, they’re more within the dish than on it. Since we’re in that plane, too, we see the plane, really, the things on it, projected across the sky as the ecliptic. We’re looking along the dish, along the plane of the solar system, toward one of our neighbors, including the Sun.

The ecliptic shows us our place in the solar system and the galaxy. It’s where we are, where our home is, among the Sun and all the other things orbiting it.

If ecliptic sounds familiar, you’re right. It’s from the same root as the word eclipse, from the Latin and Greek meaning to “fail to appear” or “to be hidden;” the Moon hides the Sun during an eclipse. The ecliptic got its name because ancient sky fans saw that solar eclipses happen when the Moon crosses the ecliptic during the new Moon phase.

If you’re able, keep an eye on the Sun, the Moon and the planets for a while, a few days, a few weeks, months, years, even. You’ll start to reliably notice where those things are. They’re always near the ecliptic, and you can use it to help you find your way around; make your way between the night’s constellations and stars. The Moon will always be nearby, too, depending on where it is in its cycle. Its orbit around Earth is tilted by about 5 degrees, relative to the ecliptic, which is why it’s near, but not on the the same line. If it were, it’d occult, block out, all the planets, and then Sun every orbit. We’d have eclipses every month. Ho hum.

You’ll start to imagine where the Sun’s path was long after it set. You’ll be able to pick out a planet from a star very quickly and easily, which is a great party trick. Mars is the red one; Saturn the yellow one; Venus the bright white one that never gets from from the Sun; Mercury the really-hard-to-see one; and Jupiter the bright one that often gets from the Sun.

The ecliptic is one of the first things I look for each night when I go out to see what’s up. It’s one of the most important tools we have for finding our way around. When we see it we’re seeing where we are, all of our family, stretched out in front of us. See if you can see it sometime. I’d love to know how you do with it.

Clear skies, everyone!


11 thoughts on “Word of the Week: Ecliptic!

  1. “…the two most distant naked eye objects in our solar system…”

    Technically Uranus is the most distant naked eye object in the solar system, though practically it is just a dim star, if you can see it at all.

    Liked by 1 person

    1. Yeah, I know; you’re right… I thought about that, too, when I wrote that. I have a hard time, though, thinking it’s *really* a naked-eye object. It’s nearly impossible, even if you know where you’re looking. With really dark skies becoming a thing of the past, it’s technically true, but very hard to says that Uranus is really for the naked eye anymore.

      Liked by 1 person

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