Music Hi, I'm Dale. Hello, I'm Jessica. Today we're going to talk to you about Mars, Saturn, and Spica. I bet you are wondering why we are talking about two planets and a star. Well, for the month of August, you can see these three astronomical bodies form a triangle in the night sky right after the sun sets. We found out about this on August 7th while we were waiting for the Curiosity rover to land on Mars. We started observing them about two hours before it did. Before we start looking at the three astronomical bodies, we need to share some terms and conversions with you. First off, the astronomical unit. This is defined as the mean distance between the Earth and the Sun. And measured as 92,955,807.3 miles. Or 149,597,870.699 kilometers. We also want to talk to you about a light year, which is the distance that light travels in one year. One light year is equal to 5.8784,9981, times 10 to the 12 miles. Or 9.4605284, times 10 to the 12 kilometers. If you are a little fuzzy or just maybe unfamiliar with scientific notation, that's okay. All you do is take that calculation and multiply it times your one light year. Doesn't matter how many that works. Mars is the fourth planet in our solar system. It was named after the Greek God of War. The distance between the Sun and Mars is 1.52 AU. Mars is also the second smallest planet in our solar system. Mars is about 1100s the mass of the Earth. This makes it very small. As she already mentioned, it's the second smallest in the solar system. This is next to Mercury. The average density of Mars is 3.93g per cubic centimeter. This compared with Earth's just over 5g per cubic centimeter. The average temperature of Mars is about 220 Kelvin or negative 63.67 degrees Fahrenheit. Mars appears to be reddish from a distance, but it's actually tan in color because of the iron oxide on the surface. Mars has two moons, Bobos and Demos, both believe to be captured asteroids. Bobos has a unique problem in that as it orbits, it's actually getting closer to Mars. And as this happens, it is hypothesized that eventually Bobos will be ripped apart by gravitational forces from Mars. Saturn is the sixth planet in our solar system. It was named after the Roman God of Agriculture, Liberation and Time. Saturday was named after the planet Saturn. Saturn is the second largest planet in our solar system. It has a mass of 95.2 Earth masses. The average density of Saturn is 0.70g per cubic centimeter. What that means is if you were able to find a pool or a tub large enough, fill it with water, Saturn would float. The average distance between the Sun and Saturn is 9.54AU. Cloudtop temperatures average out at about 95 Kelvin or negative 288 degrees Fahrenheit. Saturn's atmosphere is primarily composed of hydrogen and other hydrogen molecules such as water, things of that sort. Saturn has the largest set of rings in the solar system. This actually caused some confusion when it was first located because they were seeing the planet with the rings edge on, so it looked strange. Saturn has 62 moons. 53 of these moons have been named. One of them, Titan, which is the largest in the Saturnian system. It also holds another unique attribute that it is the only moon in our solar system that has a substantial atmosphere. Another feature of that, not exactly unique to the moon, is the major gas component of that atmosphere, which is about 80-90% nitrogen. Well, there is another world that has a rather substantial amount of nitrogen in its atmosphere that would be earth, which has a 78% nitrogen component. The larger star is a very large binary star. When we say binary star, we mean that there is one large star with a smaller companion. The larger star is 10.5 times the size of our sun, while the smaller one is 6 times the size of our sun. Spica is also a blue giant or sub-giant star, which means it gives off a lot of light in the blue, violet, and ultraviolet end of the spectrum, which is why it looks blue to us. The larger of the two stars in Spica and the smaller one are 1.2 AU apart. Spica is approximately 250 light years away from earth. Now, remember back to the conversions that we gave you at the beginning of this video. Just imagine how many miles or kilometers that is. Spica lies within the constellation Virgo, or more accurately, it's actually the way that you find Virgo because it is the brightest star within that constellation. Spica and its companion orbit a mutual center of gravity. So, one star is not orbiting the other. They're actually kind of orbiting a space between. This orbit takes up about four days to complete, which is very quick. The two stars stretch each other as they orbit into a sort of all-blown shape, which is a little different from the sphere that we're used to thinking of. Spica is around 22,400 Kelvin, or 39,860 degrees Fahrenheit. Its companion, while smaller and cooler, is still about 18,500 Kelvin, or 32,840 degrees Fahrenheit. These temperatures are both significantly hotter than our Sun. Remember earlier in the video when we talked about how Spica, Saturn, and Mars will be forming a triangle in the sky for the month of August? Well, on August 21, our Moon will join in that formation. Also, on August 31, we will be having a blue moon. That means we will have our second full moon for the month. This only happens twice a year. Well, that's all we have for this episode. Join us next week when we talk about algebra. We'll be focusing on the rules of exponents. Thank you very much. Bye-bye.