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Part 5:
L Meteors (流星)
Jogging on the Moon (月球漫步)
Neptune/Pluto Crash (海王星、冥王星撞
擊)
Goldilocks (為何地球上會有生命)
Star Travel (星際旅遊)
Contrails (凝結尾)
Earth's Core (地心)
How to See a Meteor
K: If you happen to be in a dark sky location -- and you're looking up when a bit
of space debris falls -- you might see a burning streak in the night sky -- a
meteor! More on how to see meteors -- after this on Kids Earth & Sky.
E: This is Ed.
K: And I'm Kathy for Kid' Earth & Sky, on how you can see a
meteor -- or "shooting star."
E: Tell 'em the truth, Kath. Meteors aren't really stars! A meteor is
a tiny bit of space debris -- no bigger than a rice grain -- left
behind by a comet. This icy dust is moving along in space -- until
it encounters our own planet Earth. Then the bit of debris plunges
into Earth's atmosphere. It vaporizes as its falls -- to become a
glowing streak in a dark night sky -- a meteor.
K: Meteors in showers come at the same time every year -whenever Earth's orbit intersects the orbit of a comet. Then you
might see lots of meteors -- maybe about one a minute. Okay, that
doesn't sound like very many, but it's really . . . a thrill.
E: What's more, on any clear dark night -- far from city lights -you can also see random meteors. They're not associated with any
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particular comet -- so you never know when to expect them! If
you're on a camping trip -- or out in the country -- just lie back,
Bobby Sanchez
relax and look up for awhile -- and you might see a meteor -- or
St. Marys, KS
even two or three or . . .
Age: 10
K: That's today's show -- made possible by the National Science
Foundation. Send your science questions to kids(place an '@' symbol here)earthsky.com You'll hear
about everything on the Earth . . .
E: And in the sky!
K: On Kids Earth & Sky.
Author(s): Deborah Byrd
Jogging on the Moon
K: Everytime the moon moves in orbit once around the Earth, it also spins once on
its axis. Up next -- a listener's question about how fast you'd have to move on the
moon to keep Earth continuously in view -- after this on Kids Earth and Sky.
K: This is Kids Earth and Sky. Adele in Omaha asks, "If you
were standing on the moon's equator. . . how fast would you have
to walk or run to keep your exact position in relation to the
Earth?"
E: Adele, if you were standing at Earth's equator -- and you could
run really fast -- about a thousand miles an hour -- you could
outrun Earth's spin and keep a sunset continuously in view.
K: But she wants to know about the moon, Ed! And our moon
always keeps a single face toward Earth. So -- from one side of
the moon, you'd always see the Earth. You wouldn't have to walk
or run!
E: Okay, Kathy, but what if she were on the moon -- and she
wanted to keep a sunset always in view. Then, Adele, you'd have
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Suzan Ok
to start jogging. Just because the moon keeps a single face to
McLean, VA
Earth doesn't mean the moon doesn't rotate -- or spin -- with
Age: 9
respect to everything else! To keep one face to Earth, the moon
Used: pencil and crayons.
has to spin once a month.
Description: "In my picture, a girl is
K: Yeah, and that means the sun takes two weeks to cross the sky
jogging on the moon in her purple
seen from the moon. That's slow, compared to what we see on
jogging suit."
Earth. If you were on the moon, you could keep a sunset in view
by jogging at about 10 miles an hour.
E: Adele, thanks for your question. You can ask your question with an email to kids(place an '@'
symbol here)earthsky.com. Special thanks to the National Science Foundation. We talk about
everything on the Earth . . .
K: And in the sky . . .
E: On Kids Earth and Sky.
Author(s): David S. F. Portree, Deborah Byrd
Neptune/Pluto Crash?
E: This is Ed.
K: With Kathy.
E: . . .For Kids Earth and Sky. For the past 20 years, Pluto has been closer to the sun
than Neptune.
K: But now Pluto is the outermost planet again. Whether Pluto and Neptune might
someday collide -- after this on Kids' Earth and Sky.
K: This is Kids Earth and Sky, with a question from Brionna in
Talahassee, Florida.
E: She writes, "My teacher said that Pluto and Neptune trade places
in being the farthest planet from the sun. So . . . when they're
trading places. . . will Neptune and Pluto ever collide?"
K: Brionna, Pluto is usually the outermost planet. But Pluto comes
closer to the sun than Neptune for about 20 years out of every one
of its orbits around the sun -- and, by the way, each orbit of Pluto is
about 248 Earth-years long. So, if you were to look at the orbits of
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Neptune and Pluto from above the solar system, you might worry
that the two will someday crash. As seen from above the solar
system, Pluto's orbit looks like it crosses Neptune's.
E: But, Brionna, Pluto and Neptune can't collide. For one thing, their orbits are like freeways with
underpasses and overpasses. It's not often that Pluto and Neptune are on the same level, with respect
to the whole solar system.
K: Also, for every three trips that Neptune makes around the sun, Pluto makes exactly two.
According to astronomers, this means that whenever Pluto crosses Neptune's orbit, Neptune is
nowhere nearby.
E: Brionna, thanks for your question. Our show is made possible by the National Science Foundation.
We talk about everything on the Earth. . .
K: And in the sky . . .
E: On Kids Earth and Sky.
Author(s): Beverly Wachtel, Deborah Byrd
The Goldilocks Problem
K: Say, Ed, if you had your own planet and you could put it
anywhere you wanted, where would you put it?
E: Mmm, Planet Ed . . . I'd put it close to the sun . . . no, far from the sun!
K: Uh uh. Why Earth's distance from the sun is juuust right -- after this on Kids'
Earth and Sky.
K: I'm Kathy!
E: And I'm Ed for Kids Earth and Sky. The planet Venus orbits one
step closer to the sun than Earth does. And Mars orbits one step
farther out. On Venus, it's hot enough to melt lead! And Mars is a
cold, dry desert. But Earth is juuust right for people and other
forms of life.
K: This is what some scientists call the Goldilocks problem. Why
is Venus too hot, Mars too cold, but Earth just right for life? Venus
is closer to the sun than Earth -- and Mars is farther away -- but
that's not the whole story. The answer also involves an invisible
gas called carbon dioxide -- or CO2.
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E: Carbon dioxide is a greenhouse gas. That means it lets sunlight pass through to a planet's surface
-- but traps the resulting heat. Venus has a lot of CO2 -- in thick clouds that surround the planet. And
Venus is real hot. Earth has less CO2 in its atmosphere. And on Mars, the CO2 stays in the ground -so Mars stays cold.
K: So Earth is a nice place to live because we're just the right distance from the sun -- and because
we have just the right amount of carbon dioxide -- or CO2. That's our show for today -- made
possible by the National Science Foundation. We talk about everything on the Earth ...
E: ... and in the sky . . .
K: ... on Kids' Earth and Sky!
Author(s): Deborah Byrd, Marc Airhart
Star Travel
E: Star travel is the ultimate dream of visionaries . . . like me.
K: Ed! It doesn't make sense to travel to the stars yet!
E: Oooh! Okay, Kathy -- why not?
K: Why it's not practical to use today's rockets for star travel -- after this on Kids'
Earth & Sky.
K: This is Kathy!
E: And I'm Ed for Kids Earth & Sky. Yolanda in Amarillo, Texas,
writes, "What's the closest star to the sun? And how long would it
take to get there?"
K: Yolanda, the closest star to our sun is a triple star system
called Alpha Centauri. There's a lot of space between us and this
star. If you imagine Earth as small as a grain of sand, then Alpha
Centauri would be over six miles away. Light from Alpha
Centauri takes four years to travel to Earth . . .
E: But no earthly spaceship can travel anywhere near the speed of
light! Consider the Voyager spacecraft -- launched in the 1970s -and now heading out of the solar system. The Voyagers aren't
aimed toward Alpha Centauri -- but if they were, they wouldn't Jarrell Rush
Rocky Hill, CT
get there for 50,000 years.
Age: 13
K: And that's why star travel doesn't make sense -- for now. Let's Description: "A space age jet going in
light speed."
imagine you could send a whole colony of people to Alpha
Used: Pencils and white out
Centauri. After 50,000 years, their children's children's
children's . . .
E: Okay!
K: . . . children would arrive. They might be greeted by brass bands and crowds of earthlings -- who
left Earth centuries from now -- but traveled faster -- and so got to Alpha Centauri much quicker!
Thanks to the National Science Foundation for making our show possible.
E: You'll hear about everything on the Earth . . .
K: And in the sky!
E: On Kids' Earth and Sky.
Author(s): David Portree, Deborah Byrd
Contrails
E: Hi there ... this is Ed. Have you ever seen long white streaks in the sky and
wondered what they were? Well, I'll give you a hint -- they're made out of water and
they're made by something that flies through the air. If you're still wondering, keep
listening and we'll tell you -- up next on Kid's Earth and
Sky.
E: This is Kids' Earth and Sky, with a listener's question.
K: Danielle in Denton, Texas writes, "How do jet planes make
the white streaks we see in the sky?"
E: Hey, Danielle, you know how on a cold day you can see your
breath? Pretty much the same thing happens to make those white
streaks in the sky -- which are called contrails -- short for
condensation trails. An airplane makes a contrail by pumping
warm moist air from its exhaust into colder air.
Scott McBryde
Georgetown, TX
K: As the plane flies through the atmosphere, some of the new
moisture it releases condenses into water droplets -- and some of Age: 8.5
it freezes into ice crystals. And that's what you see as a contrail. Used: Crayons
Contrails don't last very long because their source doesn't stay put.
When the plane files off, the contrail isn't replaced. Upper level winds quickly blow it away.
E: And you know, you can use contrails to predict the weather. If a jet's contrail looks kind of wimpy
-- and disappears quickly -- then the jet is probably flying through relatively dry air -- a sign that fair
weather is coming. On the other hand, a thick, long-lasting contrail indicates humid air high in the
atmosphere. So a storm may be on the way.
K: That's our show for today. Danielle, thanks for your question. If you have a science question, send
it to kids(place an '@' symbol here)earthsky.com. The National Science Foundation helps make our
show possible. We talk about everything on the Earth ...
E: ... and in the sky ...
K: ... on Kids' Earth and Sky.
Author(s): Eleanor Imster, Marc Airhart
Earth's Core
E: Whatcha doin' down in that hole, Kathy?
K: (SFX: shoveling sounds) I'm digging a tunnel to the middle of the Earth.
E: You are? Isn't it really hot down there -- like, as hot as the surface of the sun?
K: We'll answer that question -- coming up on Kids' Earth
and Sky.
K: I'm Kathy!
E: And I'm Ed for Kids Earth and Sky, with a question from
Shelby in Paducah, Kentucky. He writes, "I've heard that at the
center of the Earth, it's as hot as the sun. Is this true?"
K: Shelby, scientists have calculated that Earth's core is probably
about 10,000 degrees Fahrenheit. And that's approximately the
same temperature as the surface of the sun. But, inside the sun,
it's much, much hotter!
E: So the inside of the Earth -- and the outside of the sun -- are
about the same temperature! But the inside of Earth -- and outside
of the sun -- aren't hot for the same reasons. Earth is a ball of
rock -- and Earth's heat comes from several different things. For
example, a lot of heat is left over from when Earth first formed -billions of years ago.
Jarrell Rush
Rocky Hill, CT
Age: 13
Description: "The earth with a hole in it
showing the earth's crust, mantle and
core."
K: Meanwhile, the sun is a huge ball of gases. It's hot because -Used: Pencils and markers.
deep inside the sun and other stars -- there's a process going on
called thermonuclear fusion. This process happens when the cores of atoms join together. Fusion
creates a lot of heat and light -- which flows from the sun's center -- and then to its surface -- and
then into outer space -- to become the light and heat we see and feel around us every day!
E: Thanks for the question, Shelby. And thanks to the National Science Foundation for making our
show possible. We talk about everything on the Earth ...
K: ... and in the sky . . .
E: ... on Kids' Earth and Sky!
Author(s): Eleanor Imster, Marc Airhart, Deborah Byrd