life. Hello and welcome back. This is chapter four on Earth, Moon, and Sky. Here is the Hubble Space Telescope back in 1993 being worked on inside the cargo bay of the Space Shuttle Atlantis. The telescope has been in space since 1990. Here is an example of latitude and longitude in our nation's capital. And we can see that lines of longitude begin in England and go west. Lines of latitude begin at the equator and go north to the pole. The Royal Observatory in Greenwich, England is where the International Line of Longitude begins. The zero point. In this type of pendulum, the Earth turns underneath the focal pendulum and can knock down these little balls every quarter of an hour as we rotate beneath it. We can see the seasons because of the tilt of Earth's axis. This tilt is 23 and a half degrees. The sun's rays are stronger here in summer because of the more direct light. In the winter, the sun is at a low angle and that produces shallow radiation. We can see that here on our globe. In the summertime, the sun is high above us in the northern hemisphere. In the winter time, it is low in the sky. We can see what the Earth looks like on the first day of summer with the topic of cancer. Up here and down here facing the sun's direct light. On the first day of winter, the topic of capricorn is in the direct sunlight. In the northern hemisphere, it is winter. There is a little difference between a solar day and a side diurel. A side diurel is a side diurel and it is important. A side diurel is the amount of time for the Earth to go around the sun once, plus an extra day to make up for the fact that we are in orbit around each other. So a side diurel is a little bit longer. It changes at the international date line out here in the open waters. Stonehenge, a very ancient monument that was used to track the motions of the sun and moon. If you ever go to England, be sure to go to Stonehenge. This is a very old observatory in Mexico. The dates around the year 1000. Your lab for Module 2 will look at phases of the moon. Here we see a classic diagram of the different phases. There are eight of them that the moon goes through in a month. You will want to refer to this diagram as you do the moon phases lab. The pool of the moon has an effect on tides and water on the Earth. As we go around the moon in orbit with the Earth, we can have different tidal changes. A little bit of an effect with the sun as well. Here we have high and low tides, a side by side comparison in the Bay of Fundy in Canada. Quite dramatic. We can also have different kinds of tides depending on where the Earth's sun and moon are located. George Darwin is best known for studying the Earth's spin in relation to angular momentum. The solar eclipse is when the moon completely blocks out the sun and casts a shadow onto the Earth. We will have a total solar eclipse again in 2024. We had one in 2017. The geometry of a total solar eclipse, which I saw in 2017 in Missouri, this diagram not the scale, but a little bit of a shadow full moon hits the Earth. Maybe 120 miles in diameter. Under that shadow, we see the total solar eclipse, like we see in this picture. In our lunar eclipse, the moon goes through the shadow cast by the Earth out into space and turns a dark red. This was the 2017 total solar eclipse. Again, I saw it here in the middle of Missouri. I'm aware of you guys. And that's the end of chapter 4. Whether you enjoyed that episode of 10 Minute Astronomy, and so check out all the other videos that I play for 10 Minute Astronomy and other videos on my channel. And then hit the subscribe button right there. Thanks.