Week 9, Day 1: The Sun

This photo of the sun was captured in November 2001. Notice the sunspot activity. The photo was captured using a telescope, digital camera, and solar filter. (Photo by Fraser & Cathy Goff, Los Alamos, NM)

During week nine of Take It Outside, we are exploring our climate!

Today we are learning about the sun, our primary source of heat and light on Earth. Make sure you don’t look directly at the Sun today because it can hurt your eyes!

We would like to know if there is interest in PEEC continuing Take It Outside once the nature center is able to open again to the public. If you would like to see it continue, please fill out our evaluation form.

Blog Post:

PEEC volunteer and planetarium presenter Akkana Peck shares some interesting facts about the sun’s motion today on the blog. Check out today’s post here!

Craft:

Make a sundial! A sundial is a solar clock: a device that tells time according to the direction of the sun’s shadow. You may have tried out the human sundial in the nature center’s garden.

You can use a sundial to tell time when you’re outdoors — no phone or watch required! They usually aren’t perfect representations of the time, but will give you a good estimate.

Get instructions on how to make a sundial here.

 

Outdoor Challenge (Beginner):

This photo was captured in June 2017 using a film camera and solar filter. The photographers took a picture of the sun every 5 minutes on a single frame of film. (Photo by Fraser & Cathy Goff, Los Alamos, NM)

Your shadow moves throughout the day as Earth rotates and the sun appears to move across the sky. Test this yourself! Get a piece of chalk and find a sunny driveway or other clear place. Trace your shadow. Make sure to mark where your feet were. Come back again later, stand in the same place, and trace your shadow again. What changed? Is your shadow leaning the same way? Is it the same height? Can you figure out why it changed?

If you don’t have chalk, you can mark the position of your feet and the top of your shadow’s head with rocks. Return several more times during the day. What do you notice about the pattern the rocks make throughout the day? Share your observations with us using the form below. Be sure to take pictures and share them with us on Facebook or Instagram or by emailing takeitoutside@peecnature.org.

 

Outdoor Challenge (Advanced):

Take time today to trace out the sun’s path through the sky. You can do this activity using a camera or paper and pencil.

If you’re using a camera, use a tripod or rest your camera on a fencepost or similar stable object. Face south, and take a picture of the sky, including the horizon. Make sure never to look directly at the sun, not even through a camera’s viewfinder. Return several times during the day and take another picture of the same frame. In the evening, flip through your pictures to see how the sun moved through the sky during the day.

If you use paper, start by facing south and drawing the horizon line seen from your house on a piece of blank paper. Include prominent features, like trees or buildings. Go outside every two hours or so, and mark on your drawing where the sun is located. Make sure you don’t look directly at the sun! At the end of the day draw a line to connect the different positions of the sun. This will reveal the path of the sun at this time of the year.

The line the sun traced out is called the ecliptic line. You can imagine holding up a hula hoop across the sky that would cover this line. If you have a hula hoop, or a length of garden hose, try it! This line is special for several reasons. For one, it marks the plane of our solar system. In fact, if you go back out at night and look along the same imaginary line, you should see the moon and the planets fall roughly along it. The constellations of the Zodiac will be there too. Look for Gemini, Cancer, Leo, and Virgo in the evening sky at this time of year. Learn more about the ecliptic line here.

Consider redoing this activity as the season’s change and observe how the Earth’s tilt affects the sun’s place in the sky.

Other Resources:

Share Your Experience:

Tell us what you learn about our climate this week! We’d love to see your photos, too. Please send them to takeitoutside@peecnature.org or share them on Facebook or Instagram with the hashtag #peectakeitoutside.

Join us tomorrow to learn about the atmosphere!

The Sun’s Motion

By Akkana Peck

The sun rises in the east and sets in the west, right?

This is true, but we’re not actually seeing the sun move. When the sun rises and sets, you’re seeing the effect of the earth rotating on its axis.

But put that aside for a moment. The sun does rise in the east and set in the west … but not always in the same place, and not always at the same time. And those changes are what causes our seasons, and a whole host of other weather phenomena.

The Earth’s axis is tilted about 23½ degrees. That means that as we make our yearly trip around the sun, part of the time Earth’s northern hemisphere is tilted toward the sun, and other times it’s tilted away.

Diagram of the seasons for the Earth’s northern hemisphere. (Graphic by Akkana Peck)

When we’re tilted toward the sun, that means the sun rises earlier, sets later, and gets a lot higher in the sky. So it’s hotter, and we call that summer. When we’re tilted away from the sun, in winter, the sun stays lower and there are fewer hours of daylight, and so we’re a lot colder.

And those seasonal changes in how much sunlight we get cause all sorts of other effects — like ocean currents, the motion of the jet stream, and the seasonal warming that causes our crazy spring winds.

North and South Wanderings

This “solargraph” photo was taken through a pinhole camera and shows the sun’s path over the course of a year. (Photo by Elekes Andor)

The sun is farthest north on the summer solstice. This year, that’s June 20, and at noon the sun will be 77 degrees up (that’s 1 PM on our clocks due to Daylight Saving Time). We’ll have 14½ hours of daylight on that day.

On December 21, the winter solstice, the sun will only make it up to 30 degrees above the southern horizon at noon, and it will only stay up for 9½ hours.

This “solargraph” taken from Budapest used a pinhole camera (with actual old-fashioned film!) to capture the sun’s path through the sky over a whole year. You can see how much its path changes in summer versus winter.

 

Where Does the Sun Rise and Set?

Notice in the solargraph that the sun’s rising and setting position also changes over the year. It doesn’t rise exactly due east, or set exactly due west, except on the spring and fall equinoxes.

You can see this for yourself at home. Make a note of where the sun rises or sets today against a local landmark, like the Sangre de Cristo Mountains or Jemez Mountains if you can see them from your house. Then check again a week from today, and again in a month. How much does it change?

Be careful when doing this: don’t ever look at the sun directly, since it’s bright enough to hurt your eyes even when it’s rising or setting. Check it just as the last bit of the sun is disappearing behind the Jemez, or better yet, take a photo as it’s setting (but don’t look through the camera’s viewfinder, if it has one; just use the LCD screen).

The Analemma

There’s more to the sun’s motion than just north and south. Because the Earth’s orbit isn’t a perfect circle, sometimes we move faster in our orbit, sometimes slower. So sometimes the sun seems to lag a little behind, or race a little ahead, of where you’d think it should be — for instance, it might reach its highest point at 12:17 PM, or 11:46 AM, instead of exactly 12:00 PM noon (or 1 PM MDT).

If you pointed a wide-angle camera at the sky and took a photo every day at the same time over a whole year, sometimes the sun would be a little farther left, sometimes a little farther right, as well as moving north and south. You’d get a picture like a figure-eight, or a bowling pin:

This picture shows a morning analemma. (Photo by Giuseppe Donatiello)

That’s called the analemma. You may have seen it on globes of the Earth. The top of the figure-eight is near the summer solstice, when the sun is high; the bottom is near the winter solstice. If you take your photos at noon, the figure eight will be roughly vertical; if you take it in the morning or evening, it will be tilted, as in this morning analemma by Giuseppe Donatiello.

Take a closer look at the sun through today’s craft and outdoor challenges!