Starlab - SMARTSTEM Program of Spring ISD

Editor's Notes

• #2: This powerpoint usually takes me approximately 45 minutes to complete. During shorter shows, I typically cut out the section on lunar phases, the section on seasons, or the section on the stars & H-R diagram. Sometimes I only show one section. My favorite to show 8th grade students is the stars/H-R diagram section, since that is entirely new content for them (according to the current TEKS).
• #3: Welcome Home! *click*What does this line represent? What does it tell us about our planet? What is happening around this line? (axis, north & south poles, spinning around or rotating around the axis) *click*What does this other line represent? How does it divide the Earth? (Equator – divides the Earth into the Northern and Southern hemisphere)What’s wrong with this picture? (lines are imaginary, no other planets/stars/moon(s)/asteroids, etc - EARTH NOT TILTED TO 23.5 degrees!)
• #4: So let’s add the sun to this picture. *click* If the sun is shining on the Earth, what are you experiencing when you are on the backside of it? (night)What are you experiencing if you’re in Africa, where the Earth is turning, taking you from day into night? What does the sun look like it’s doing? (sunset)What about the far side of the Earth, that we can’t see in this picture? You would be moving from dark into the light. What does the sun do? (sunrise)
• #5: So the Sun is not the only other thing in our solar system. There is also a smaller system between the Earth and the moon.How does the moon affect the Earth? (we see phases at different times during the lunar cycle, it pulls on the water nearest the moon, causing high tide)
• #6: What did I change in this picture? (tilt!)Was the Earth the only thing that tilted? (no, the moon’s orbit did, too)Funny thing – the moon’s orbit is tilted, although it doesn’t always look like this. *click*The moon’s orbit actually WOBBLES. But what would happen if it didn’t wobble? What if it were always perfectly flat?
• #7: So let’s put the sun into that picture. If the sunlight comes from the right hand side, *click* what happens to the backside of the Earth? (it is dark)So the back side of the moon *click* will be dark too, right?Now, if the orbit were to tilt perfectly flat… *click*Would the moon be lit up in this position? (no!) *click* Why not? (the earth is blocking the sun, the moon goes into the earth’s shadow)What do we call it when the moon seems to go into a shadow and comes out the other side? (eclipse)So lunar eclipses occur when everything lines up JUST RIGHT, and the orbit wobbles flat at the same time the moon passes directly behind the Earth.But usually the orbit isn’t perfectly flat like this. Usually it’s tilted…
• #8: So if it is tilted, light can still reach the moon.What if I’m standing on the Earth, right in the middle of the dark side at midnight, and I look up at the sky? What will I see? (full moon)
• #9: What if the moon *click* moves over here?If I’m standing on Earth looking up at it, what can I see? (nothing, it’s a new moon)What time of day would I have to look to try to see the moon? I mean, if it was the middle of the night, would it even be POSSIBLE to see the moon, even if I could shine a REALLY bright light up at it? (no, it’s on the other side of the Earth).So the moon rises and sets at different times in its cycle, depending on its location in relationship with the Earth!How long does the moon take to complete a WHOLE cycle? (28 days/about 1 month – almost exactly 4 weeks)So how long would it take the moon to go from full to new, where it is now? (14 days/2 weeks)
• #10: So if it takes 2 weeks for the moon to go from one side to the other, how long does it take to complete ¼ of the cycle? *click* (1 week)If I’m on Earth looking up at the moon, what will I see when it is in this position? (3rd quarter)
• #11: (YOU CAN REPLACE THIS WITH THE CURRENT MONTH’S CALENDAR - FIND A DARK ONE w/ GOOGLE IMAGES & move the moons )Start with the first new moon – What moon phase is it when you can’t see the moon at all? *click* (new moon)What about 2 weeks/14 days later? (full moon) *click*What about 4 weeks/28 days after the new moon? (another new moon) *click*What happens halfway between the new and full moon? (first quarter) *click*What about b/w full and new? (last/3rd quarter) *click*So we see the 4 main phases, which only last for one day at a time. But we also have phases that sort of grow and shrink between these, right? So that happens after the new moon, as the moon is growing, before it becomes 1st quarter? (waxing crescent) *click*Between 1st quarter & full? (waxing gibbous) *click*Between full & last quarter? Is it still growing or shrinking? (shrinking – waning gibbous) *click*Between last quarter & new moon? (waning crescent) *click*
• #12: Great job with the moon phases, but now we need to talk about the SUN and the Earth’s system.If the light from the sun *click* is coming out and hits the Earth, which hemisphere gets more light? (southern hemisphere)So what season is it here in the northern hemisphere? (winter) *click* Why? (we get less energy from the sun)What are they having in the southern hemisphere? (summer) – they always have the opposite from us.This happens around December 21st each year.
• #13: Wait a minute – does the Earth ever pass above the sun? (no) Why did I draw the picture like this? (Earth would be hidden behind the sun if you drew it correctly) So right now you’re peeking over the sun, looking off at the Earth in the distance. Keep that in mind as we talk about this…When the sunlight strikes the Earth, *click* look where it strikes. Does it hit one hemisphere more than another? (no, it strikes right in the middle)So both hemispheres receive equal amounts of light – equal light, and we have equal hours of day and night. This is called an “equi-nox” *click* Equi- means equal, -nox means night.What season is this? Remember we just had winter… (spring)So “vernal” means spring.This day happens about March 21st each year.
• #14: About 3 months later, which hemisphere is pointed toward the sun now? (north) Has the tilt of the Earth changed? (no, its position has changed)What season is it for us up here in the northern hemisphere? (summer) *click* How do I know it is summer? (more sunlight hits the northern hemisphere)So what are they having in the southern hemisphere? (winter). This happens around June 21st each year.
• #15: Last, but not least, the Earth passes in front of the sun here. What season comes after winter, spring and summer? (fall, autumn)Are the axes pointed toward or away from the sun? (neither, they point off to the sides).What’s happening with the sunlight that strikes the Earth? (it hits at the equator, it hits the north & south evenly)What did the word “equinox” mean again? (equal night)This happens around September 21st each year.
• #16: Now let’s look at the other planets in our solar system.What do these four planets have in common? (small, rocky/solid surface, close together, warm, few moons (Mars has the most with only 2), inner planets)Are they in the correct order? (No, it should be Mercury, Venus, Earth, then Mars)Why did they put them in this order? How did they classify the planets? (according to size – they put them from smallest to largest)Ok, we’re going to zoom out a bit. Remember how large Earth is in this picture…
• #17: Now see how large the Earth is? We’ve zoomed out so we can compare the size to these four planets. What do these four planets have in common? (larger, gaseous, distant, cold, spread out, they all have at least one ring, multiple moons, etc)Are they in the correct order? (No, it should be Jupiter, Saturn, Uranus then Neptune)Why did they put them in this order? How did they classify the planets? (according to size – they put them from smallest to largest)Ok, let’s zoom out again…remember how big Jupiter is here.
• #18: Now we’re going to step outside of our solar system. When you think of Solar system, I want you to think of it as our “neighborhood.”How many stars are in our solar system? (one – the Sun)Well, now we’re going to look at some of our nearby stars. These guys aren’t in our neighborhood, but they are just around the corner from us.You see Jupiter here as a size comparison. See how small it is compared to the sun? The Earth would just be the size of a speck on this screen, not much more than the dot on the “i” in Jupiter.
• #19: So let’s see if we can find those stars on this chart. This is called the H-R Diagram, created by Hertzspring & Russell – H-R. They plotted each star based on characteristics they could measure or calculate from here on Earth, looking for patterns to explain why the stars are the way they are. They picked 2 characteristics to compare: brightness (or magnitude/luminosity) and temperature. This version of the H-R Diagram gives you a really good hint here – how could they tell the temperature? (the color of the star)So let’s see if we can find those last three stars on this chart. First *click* find Wolf 359. What color was it? (red) *click*Now look for the *click* sun. What color is our sun? (yellow) *click*Now let’s find Sirius, also called the Dog Star. What color was it? (blue) *click*What section did all these stars fall in? (main sequence)Notice, the main sequence follows a pattern. As the stars get brighter, they also get hotter…Brighter = Hotter. This graph even shows you the relative sizes – what happens to the size of the stars as they get brighter/hotter? (they also get bigger) So in the Main Sequence, the stars follow the logical pattern… Bigger = Brighter = Hotter. That’s why these stars are in the main sequence – they are the “normal” stars. In fact, if I could graph ALL of the stars we’ve ever seen, you’d find that almost all of them would fall on that main sequence somewhere – because these are the “normal” stars. But not all stars are “normal”…
• #20: Ok, so remember how large Sirius is, because we’re going to zoom out again.
• #21: That little blue one – that’s Sirius now. So are these stars bigger or smaller than the sun? (bigger)This is Pollux, Arcturus & Aldebaran. What do you notice about the color of these stars? (they’re all orange)What does that tell you about the temperature? (they’re all the same temperature – cooler)Even though they’re dramatically different sizes, they’re all close to the same temperature.Let’s find them on our H-R Diagram, too.
• #22: Do you see *click* Pollux? What color was it? (orange) So look in the orange stars… *click*How about *click* Arcturus? Also in the orange stars *click*And lastly, *click* Aldebaran. Still orange. *click*What section did these stars land in? (giants)Notice, these giant stars don’t follow the same pattern as the Main Sequence – as the giants get bigger and brighter, they actually cool down.But those giants aren’t the biggest stars…let’s zoom out one more time…
• #23: Remember how Aldebaran is here, many manymany times larger than our sun.
• #24: So here is Aldebaran now. Pretty small, huh? What about these next 3 stars…they are MASSIVE stars. Absolutely HUGE.The little blue one, it’s not actually little – it is many many times larger than our sun.Which of these 3 new stars is hottest? (rigel) Which is largest? (betelgeuse)In fact, Betelgeuse is one of the largest stars we can see in the Universe!I’m going to ask you to remember two of these stars – I want to show you how to find them in the night sky. The two I want you to remember are Rigel and Betelgeuse. (have students repeat the names a few times while you point at them and ask questions like, “which is bigger?” “which is hotter?”)Ok, let’s find these on the H-R Diagram.
• #25: So there was our last star we found. Do you see *click* Rigel? What color was it? (blue) *click*How about *click* Antares? What color? (orange) *click*And everybody’s favorite, *click* Betelgeuse? (red/orange) *click*What section did these fall in? (supergiants)Notice that the Supergiants don’t follow even the last pattern? They are all incredibly large, incredibly bright, and yet, they are quite a wide variety of temperatures, going all the way across the graph.So astronomers puzzled and puzzled and puzzled about this – why are there different kinds of stars? What causes them to be different types?Until they realized…we don’t have different types of stars…
• #26: …We have different ages of stars.Turns out that throughout the life of a star, it actually changes its behavior.They all start out as a huge cloud of hydrogen gas called a stellar nebula.
• #27: Over millions, or even billions of years, that hydrogen gas draws together, tightens, condenses to form a sort of clump. Here you see a clump of hydrogen atoms that collected over many many years. But it doesn’t stay that way for long *click*As the clump of hydrogen grows, the gravity increases and the atoms start to get pulled in from farther and farther away. They start to get pulled in faster and faster.The clump grows, and keeps growing faster and faster until there is no more hydrogen around to pull in (because it was captured by other clumps growing nearby).
• #28: At the center of that clump, in the beginning, the hydrogen atoms just sort of gently bounce into each other… *click*
• #29: But as the clump of gas grows, *click* the atoms are pulled in harder and faster…
• #30: *click* …and faster and faster…
• #31: Until finally they get pulled in SO HARD and SO FAST that the two atoms don’t just bounce… *click* the atoms actually stick. We call this fusing.So the nucleus of one atom and the nucleus of the other atom SMASH INTO each other and fuse. Nucleus, nucleus – FUSE. That’s nuclear fusion.Now instead of being an atom with one proton in the middle it has two. It isn’t hydrogen anymore, it’s helium.When these two atoms collide and fuse, they release a huge BURST of energy…in the form of light.Now this isn’t just a clump of hydrogen gas…it’s glowing…so it can officially be called a star.
• #32: If you start out with a smaller or average-sized star, it will follow the top of this diagram. If it is larger, it goes through the same basic processes, but it looks a little different, because it has much more mass and is so much hotter.So with our sun - an average, yellow star – we start out fusing hydrogen. This continues for a loooong time, until finally, the star runs out of hydrogen. We think that our star has a lifespan of about 10 billion years. Something like 9 billion of that is spent in this first stage, fusing hydrogen – most of the life of the star. This is when they act “normal” – and these stars can be found on the main sequence.When it eventually runs out of hydrogen, it doesn’t just go out…it begins to fuse the stuff that is left behind. But now it doesn’t give off as much energy, so it cools down and spreads out to form a red giant. How can I tell it cooled down? (the star changed from yellow to red). But that star can’t spread forever - after a while, that red giant gets really unstable, until it finally collapses. Most of the star collapses into the center, but it kicks out a huge cloud of dust, creating a planetary nebula. What do you think forms from that planetary nebula? (planets)At the core, you’ll still have a star, but now it is tinier, and much denser. It has an amazingly strong pull of gravity for an object of its size. And although it is still continuing nuclear fusion, it actually dims and fades to become a white dwarf.Now, if you start with a larger star, you go through the same processes, but faster, and more violently. The massive star runs out of hydrogen, expands and cools to form a red supergiant. Then, when it finally collapses on itself, it actually does it so fast that the still-fusing gasses sort of “splash” back out. Basically, the star explodes while it is still glowing. That’s called a supernova. What you have left at the end is a core so incredibly dense and tightly packed that it shoots out powerful plumes of radio waves, creating a neutron star. The gravitational pull of a neutron star is so powerful, it can actually pull nearby stars into orbit around it, even pulling them together completely.But if you start the process with the most massive of stars, and it goes through the whole thing, through supernova – at the end it can actually become a black hole. I know when you think of a black hole, we tend to think of it being a pathway, or a portal. Actually, a black hole is basically just a super-dense neutron star. It is still a star at the center of the black hole, but the gravitational pull is so strong, not only does the black hole pull in nearby objects, like planets, stars or whatever is nearby – it will actually have enough gravitational pull to drag light in, too. The gravity is so intense that even light can’t escape. That’s why we weren’t sure for a long time if black holes actually exist. The black hole is invisible to us.
• #33: Ok, one last thing.Here’s a lady standing at the north pole. Not only is she way too big, she’d also be really cold…So if she is standing at the north pole and she looks *click* straight up above her head, *click* this area of the sky will be visible to her.*click* Would she ever be able to see the moon pass directly over her head at the north pole? (no)Why not? (because it travels around the center, around the equator)
• #34: So let’s put her in Houston. Pretty funny looking right? Is this what you feel like you’re doing when you stand up? Actually we are standing at an angle like this – we don’t fall off, because gravity isn’t pulling us to the bottom of this picture, it’s pulling us toward the center of the earth. So from her feet toward the center is “down” to her. And *click* this is “up.”If she looks up above her head now, *click* this portion of the sky will now be visible.*click* So if she looks up above her head here, will she ever see the moon pass directly overhead? (no)Why not? (it is still going around the middle)Where would she have to stand to see the moon pass directly over her head? (equator)Excellent – keep this picture in your head, because when we look at the stars in here, this is the angle of the sky we’re going to see – it’s hard to tell just looking at the stars, so keep this in mind!(Turn off LCD projector, close computer, and turn on the Starlab projector)Starlab Projector Agenda:(topics: galaxies, light pollution, seasons, constellations, stars, distances in lightyears, and moon phases) Milky Way Why don’t we ever see the Milky Way, even when it is right above us? (light pollution) Identify directions (N, S, E, W) Big Dipper Little Dipper (don’t name the north star yet)- Spin projector to show how the stars “move” across the sky at night, until dawn arrives North Star/Polaris Sunrise during Fall Equinox (why does it rise directly in the East, set directly in the West, yet it doesn’t go directly over us?!) Sunrise during Winter (point out – indirect sunlight at noon) Sunrise during Summer (point out – direct sunlight at noon) Which path is longer? (summer!) What does that give us? (longer days in the summer)Orion’s belt (and outline Orion, the hunter) Betelgeuse & Rigel (approx. 430 & 770 lightyears away, respectively) How long would it take to get to Betelgeuse? – the fastest humans have ever traveled is approx. 1/20 the speed of light, so multiply 430 x 20 to find a rough estimate of how long it would take us to get there…  Sirius (only 8 ly away – one of the closest stars to us, and the closest one visible at night in the northern hemisphere) 430 (or 770 or 8) lightyearsalso means that the light took 430 (or 770 or 8) years to reach us – the image we see of that star is 430 (or 770 or 8) years old! Moon phases