Hello Astronomers! For the last two weeks I’ve shared with you some of the thrill we’ve experienced when we’ve seen eclipses of the Sun and Moon. A solar eclipse happens when the Moon passes in front of the Sun. Lunar eclipses happen when the Moon passes into the shadow of the earth. When do these things happen? Why don’t the happen more often? Want to know? Read on!
Hello Astronomers! In the last issue, we talked about shadows. Shadows are why we have special events like lunar and solar eclipses. Let’s look again at lunar eclipses. We know that the Earth casts a shadow out into space in the direction of the anti-solar point. Remember, that’s the point directly away from the direction of the sun.
Can we ever see evidence of Earth’s shadow besides when there is an eclipse of the moon? Yes!
Hello Astronomers! One of the things I love about observing the night sky is that what we see in the sky makes sense, once you apply a little thought to them. For example, think about shadows. You know, light can’t go through solid stuff like your house or your head. Let’s think about shadows.
Here’s a picture I took from the roof of my house that shows my shadow. Sunlight is blocked from reaching the ground. The shadow of my head is located at the anti-solar point .
Knowing where the anti-solar point is, helps us to understand a lot about how the Sun affects what we see in the sky. More about that in future articles.
I promised that I would talk to you about eclipses. A solar eclipse happens when the Moon’s orbit carries it to a point in space directly between the Sun and just a small spot on the Earth. The Moon makes a shadow on the Earth just a few miles wide and people like me go to a lot of trouble to get to that spot on Earth just to be in the Moon’s shadow. We love to see scenes just like this!
Here is a picture I took from just the right place and at just the right time in 2017 of the total solar eclipse. We were in Hopkinsville, Kentucky. You’re seeing the night side of the Moon exactly in front of the sun. This view was about as bright as the Full Moon.
This is the ONLY time it is safe to look toward the Sun without special glasses.
The best rule is that you should NEVER look toward the sun. You can cause permanent eye damage or be blinded for the rest of your life. There are special filters and other ways to observe the sun. When we can have in-person talks again at the FOC, I’ll tell you about some of them.
Here’s a picture taken from space at the same time as I took my picture above. Can you make out the shape of North America? The Sun was completely covered-up at the very center of the shadow shown on the Earth. The anti-solar point is at the center of the Moon’s shadow.
This diagram shows how sunlight on its way to the earth is stopped by the Moon. So the Moon casts a shadow, just like your head, the Moon and the Earth!
The other kind of eclipse is called a lunar eclipse. I took this picture in 2014. The Earth is much bigger than the Moon. So the shadow that the Moon makes on the earth is pretty small. But the Earth’s shadow is much bigger. It’s so big that the entire Moon can fit inside it! So when this happens, the whole Moon can go dark. The Earth’s the anti-solar point is at the center of its shadow.
Most of the time the Moon looks white and grey but during a lunar eclipse it turns a reddish-orange. That’s because some of the light from the Sun is bent around the Earth by its atmosphere. Did you know that the moon is about as reflective as a piece of black construction paper? Lunar eclipses can turn the Moon almost black or a light orange. More about that later.
There’s a lot to know about eclipses. Next time we’ll learn more about when to look for an eclipse and what we can expect to see!
Hello, Astronomers! Well, I guess that this week wasn’t the best for Moon watching was it? I heard the weatherman on TV say that this has been one of our wettest springs ever. The clouds that brought the rain sure blocked our view of the sky most evenings!
Did you manage to get more phases drawn in on your Lunar Observing Record Chart? If you did I’d love to see how you did. If you can, scan your chart and send it to me at email@example.com The best way for us to understand nature is to find more than one way to show that something is true, or at least likely. Last time, I showed you a model that demonstrates how the moon changes phases throughout the month. Now I want you to see a different way to explain these phases.
Try This. Ask if you can borrow a couple of things that you probably have around the house. First, find a ball. The ball must be round, a baseball will work fine, but not a football! Next, find a flashlight, the brighter the better. Now go into a darkened room or wait until night and place the ball on something that will hold it still, at eye-level and visible from all directions. Place your flashlight on another table, level with the ball. Point it at the ball and then walk around the table. How does the ball look from the same direction as the flashlight? How about when you see the ball in the same direction of the flashlight?
Check out the illustration below. Each of the four observers are looking at the ball that is lit by the flashlight. Can you draw in their circles what you think how each observer sees the ball? How does the ball appear to each observer?
Look at the illustration below. Instead of you moving around the ball, the ball moves around you-like the Moon! Using what you’ve already learned about the Moon’s phases, can you guess which phase the “Moons” below would show you as they revolve around your head? Draw the shaded parts of each ball below and write which phase is showing to the observer in the middle.
Finally, let me leave you with a beautiful picture by my friend, Steve, that shows the phases of the moon over entire lunar cycle, or ‘moonth’.
Hello, Astronomers! I’m back with this week’s ideas to help you get to know the night sky. I also decided that it was time to give this a name: Looking Up! How do you like it?
Last week I invited you to pay attention to how the Moon appears to change shape from night to night. We’ve had some cloudy nights but I managed to get a few drawings done. I fund that a penny works well to help me draw the line between the bright and the dark areas on the Moon when the moon is still a thin crescent.
Here’s what I did as of Wednesday.
Here’s how the moon appeared last week during one of it’s crescent phases.
Have you ever wondered what makes the moon seem to change its shape from day to day? We can see the planets and moons in the solar system because they reflect sunlight. Most of these are spherical, like a basketball. Astronomers say that gravity will cause most objects in space bigger than 200 kilometers wide (about the distance between Berea and Cincinnati) to be round, like a ball. Sunlight always shines on ½ of a ball. Remember our first activity when you made a solar clock? I asked you to notice how much of a ball was lit by the sun when you took it outside.
The moon is a sphere. The bright part we see is part of the half that is lit by the sun!
I like to build models that help me (and other people) understand what we see in the night sky. Check out the picture below. I put a webcam inside a plastic Christmas ornament ball. We’ll call that the earth, in green, on the drawing below. I placed a golf ball to represent the Moon on a platform that let’s it move around the “Earth” in a circle. This is how the real Moon revolves the real Earth. I put another camera above my “Earth” to look down on my “Moon” and my “Earth.”
Now, the fun part. With a bright light shining on the model I rotated the “Moon” into the
The sizes of my plastic “Earth” and golf ball “Moon” are about right, relative to each other. But my “orbit” of the Moon is way too small. In fact, if I made the circle the my “Moon” revolves on to the right scale, it would have to be 48 feet across!
I hope you’ve enjoyed my demonstration as much as I’ve enjoyed putting it together for you! Think about this demonstration as you continue to track the ever-changing face of the Moon!