Jane: This is But Why: a Podcast for Curious Kids from Vermont
Public. I'm Jane Lindholm. On this show, we take questions
from curious kids just like you, and we find answers. One of my
favorite things to do on a summer night is to go outside
after dark and look up at the night sky. In Vermont,
especially in rural areas like where I live, we don't have a
lot of light pollution, and I can see so many stars. Well, as
long as the moon isn't shining super bright. Right now, for
this episode, we're going to go stargazing, and it doesn't
matter if you're listening on a bright sunny day, sitting in a
car or a classroom, or lying on your bed. It doesn't matter if
you live in a city and you do have a lot of light pollution
and you have trouble seeing as many stars, and it doesn't even
matter if you're in the northern hemisphere because we're going
to go to the southern hemisphere too. We're going to stargaze in
this episode with the help of a very special place called a
planetarium. I went to the Museum of Science in Boston to
do some middle of the day stargazing, but if you want to
wait and take this episode outside with you at night, and
maybe take some bug spray too, if you have a mosquito-filled
yard like mine, all the better. Let's meet our celestial guide,
Talia Sepersky.
Talia: So I am somebody who works in a planetarium, which is
a place usually dome-shaped room where we're very good at
simulating the night sky, so we can pretend that we're out on a
clear, dark night looking up at constellations.
Jane: As Talia said, a planetarium is a big
theater-like room. Often the seats lean back, and they make
it nice and dark and cozy. Sometimes it's really cool in
there as well for some reason, and images are then projected up
onto that dome-shaped ceiling. Planetariums have been around
for over 100 years now in some places, and they got really
popular in the 1950s and 60s. Often, what's projected onto the
ceiling is the movement of the planets and stars. Using special
technology, the projector can often be programmed to show you
the sky on any night and at almost any time, past, present,
or even future.
Talia: And in our planetarium, we can also pretend to fly
anywhere in the universe. And I am the person who will be there
helping fly and helping to tell everybody what they're seeing
because I love talking about space.
Jane: And you don't even need a pilot's license or to be an
astronaut.
Talia: Not for this spaceship, no.
Jane: So it's like 240-five or three in the afternoon here,
bright sunny day. But here we are inside the planetarium at
the Museum of Science in Boston, and it's very dark. And up above
us, there are some squiggly lines. What are we looking at?
Talia: We are actually looking at a nighttime sky. And what I
have done is, those squiggly lines are the constellations.
There are 88 official constellations, and these are
the ones that are up over New England tonight.
Jane: All right. So tonight being August 7, the day this
episode is being released. So this is what the sky would look
like, maybe around bedtime or just after bedtime for a lot of
the kids who are listening.
Talia: Yep, I've got it set for 9:00 right now because August is
the time of the year where the sun is, you know, setting really
late. So if you want to get a nice dark sky to go stargazing,
you do have to stay up a little bit later, at least in the
northern hemisphere.
Jane: That's right. If you're in the southern hemisphere, it's
probably pretty dark, and maybe you'll fly our special vehicle
over to the southern hemisphere a little bit later.
Talia: We can absolutely do that. One of the great things
about being here in the planetarium is not only can I
instantly go anywhere in the universe, I can instantly go
anywhere on Earth.
Jane: So this doesn't look much like the sky if I was looking up
at it because of these lines, and these lines are outlining
constellations. One of the questions we've gotten is, "What
is a constellation?"
Skyla: Hi, my name is Skyla, and I am six years old. I live in
San Diego, and where do constellations come from?
Liam: Hi, my name is Liam. I'm 10 years old. I live in
Stuttgrat, Germany, and my question is, why do we have constellations?
Harry: My name is Harry. I live in New York City, and my
question is, how are constellations formed?
Talia: A constellation is really any pattern or shape that you're
making. Out of the stars in the sky, we have, as I said, 88
official ones. But that's just from really one culture's
patterns, sky patterns that they made. There's actually thousands
of different sets of constellations out there because
it was very, very common in ancient times for people to look
up at the sky and make shapes out of the stars, and give those
shapes names and tell stories about them. So a constellation
really is any shape or pattern that you're making out of the
stars. And I always tell kids to go outside with their adults on
the next clear night and make up their own.
Jane: Yeah, I think that's fun. It's like looking at clouds and
seeing shapes. You can make up your own star patterns.
Talia: Oh, absolutely! The human brain loves making shapes and
patterns out of things.
Jane: And that's actually what people have done since there
have been people. It's not just us here saying make up some
patterns. Like that's why we have constellations because
people love to do that.
Talia: Absolutely, we think astronomy may be the oldest
science there is because people have been looking up at the sky
and noticing things about it since ever, as far as we know.
Jane: And maybe even some animals too. My dog will look up
and find the moon, so I wonder if some animals look at the sky
and see stars. And we know some animals navigate with celestial
navigation using the magnetic field of the Earth and using
things like weather patterns and sky patterns to actually
migrate. So we're not even the only creatures out there looking
up at the stars.
Talia: No, one of my favorite stories is apparently dung
beetles track their movements against the Milky Way, and I
know they've done experiments where they've actually released
birds inside of planetariums and seen the birds orient themselves
based on what star patterns they had projected on the ceiling.
Jane: No way, really.
Talia: Yeah, so there seems to be bird species as well who, at
least at some level, are using sky patterns as a navigational
tool.
Jane: Wow, and even within a planetarium, so not even just
outside, but they're actually looking at the patterns when
they're not even real stars.
Talia: They don't know they're not real.
Jane: So I'm looking straight up right now at one constellation
that's kind of you know kind of like shaped like a house, I
guess, a traditional house that you might draw when you're a
little kid, and then coming out from the house is what looks
like a claw, and it looks like a crab. Tell us about that
constellation.
Talia: So that's actually an interesting one because that
historically was one constellation, and it has since
been split up into three because it's so big. So that house shape
in the middle is ophichus, the serpent-bearer, and the lines
that are coming off of either side, that's the snake that the
serpent bearer is holding, and the side that looks like a claw,
that is the the snake's head, so that one is serpens caput, which
means serpent's head, and then the other side is the tail.
Jane: Wow, that's so cool! And next to it, it looks like the
serpent is almost-it's-it's reaching towards a kite, or you
might think of it like a stingray.
Talia: Yes, I love that stingray. That one is actually a
a part of what we call the Summer Triangle. It's three
constellations that you can see, pretty much from anywhere in the
northern hemisphere, and you know there's a chunk of the
southern hemisphere that might be able to see it as well. And
it's really three bright stars in the summertime sky, and each
of those three stars is in a different constellation, and one
of those constellations is that stingray-looking one-that is
Aquila the Eagle.
Jane: Aquila the Eagle. Where do people come up with these names
and the stories that go along with them? Because you said
we're looking at kind of one culture's interpretation of the
sky.
Talia: Yes. So these names I'm giving you and these shapes I've
got up on our planetarium dome, these represent those official
constellations, which are mostly the ones that were made up by
the ancient Greeks and ancient Romans. That is the set that's
been sort of accepted to be the one set that everybody can use
as a reference point. But they're certainly not the only
ones who were doing this.
Jane: Tell us about the one that's very clearly shaped like
a W.
Talia: Ah, the W. That one is actually supposed to be a queen
on her throne. That is the constellation Cassiopeia, the
queen. Frankly, right now it looks like a W. At different
times of the night and at different points in the year, it
looks like an M or an E or the number three.
Jane: Right. So, Talia, I mean, it's kind of a stretch to get
some of the animals and images that we're supposed to be
seeing. And I can remember as a kid being told about the
constellations, and one of them, for example, Orion, who I could
always find Orion's belt. That was a series of stars that was
easy for me to find, but then I would look up and be like, you
gotta be kidding me that you see a whole guy hunting in this star
pattern. I couldn't find it. Somebody would need to draw on
the sky for me to see what they're talking about.
Talia: Yeah, there's a lot of constellations that you really
got to scratch your head and wonder what they were thinking.
I always tell people, well, you gotta you know also remember
that back in the day, you know, imagine you're in ancient Greek
or in ancient Rome, and you're looking up. It's the middle of
the night. You don't have anything else to do. There's no
television. You can't, you know, play on your Switch. You're just
looking up at the stars, and sometimes their imaginations
seem to be really far out there.
Jane: I want to ask you more about the constellations, but we
should probably back up because we have other questions that
might help us understand a little bit more about the night
sky and what we're looking at when we look up at the stars.
Johannes: My name is Johannes. I'm four years old. I live in
San Francisco. How many stars are now?
Bobby: My name's Bobby. I live in Houston, Texas. I'm five and
a half years old, and I wanna know how many stars are there.
Oscar: Hi, my name is Oscar, and I am five, and I live in Hong
Kong. How many stars are there in the whole universe?
Luke: My name is Luke. I live in Chester, Connecticut, and I'm
five years old. My question is: How many stars are there in the
universe?
Talia: We have no idea, but it is a very, very, very, very,
very big number. So, just to give you an idea, you know, our
sun is a star. It is one of the stars in the Milky Way galaxy.
The Milky Way galaxy contains a few 100 billion stars, and it is
only one of about 2 trillion galaxies that we know about. And
some of those are bigger than the Milky Way, and some of them
are smaller. But you start to see that there's there's a lot
of really big numbers out there, and we can't really put a hard
number on how many stars there are. One analogy I've heard used
a lot is that there are more stars in the universe than there
are grains of sand on all the beaches in all the world, but
the answer is very, very large.
Jane: So, if everybody who's listening now started counting
and didn't stop counting for the rest of our lives, we probably
still all together wouldn't have counted the number of stars
there are out there.
Talia: I don't think so. I think it would take one person to do
the Milky Way alone their entire life if they were, if they
devoted their entire life to counting one star per second, in
just the Milky Way, it would take, and they, and they lived a
nice long life. It would take their whole life, and that's one
person. And then you've got the other 2 trillion galaxies to
worry about.
Jane: Yeah, and then we can't even stop for snacks.
Talia: No, you can't stop. You just got to do nothing but count
stars.
Cam: Hi, my name is Cam. I'm six and a half years old. I live in
Ambler, Pennsylvania. What are stars made out of?
Talia: So stars are made out of pretty basic gasses, actually.
If you've ever looked at a periodic table, maybe you have
them in your classrooms, or if you've ever heard of things like
hydrogen or helium, it's the same thing that's making up
stars. Stars are mostly made out of hydrogen and helium, and what
happens is there are these enormous clouds of these gasses
out in space, and something, can be many things, will start that
gas cloud to collapsing down on itself, sort of squishing all
the gas together, and it will form a big clump of gas. And
that clump will get bigger and bigger and bigger, and as it
does, it will also get hotter and hotter and hotter in its
insides. And then once it gets hot enough, it's actually going
to start smashing those atoms together, and this is something
we do on Earth. It's called nuclear fusion. It is a way we
can generate energy, or a way we hope to generate energy at least
on Earth efficiently someday. And stars are doing it. And
basically, when you smash hydrogen atoms together hard
enough, they release a ton of energy, and that's what makes a
star a star. It is this giant ball of these roiling gasses
that is smashing atoms together and generating a bunch of energy
in the form of heat and in the form of light, and that is why
the sun is so warm, and it's why the stars shine so brightly.
Spencer: Hi But Why? My name is Spencer. I'm 10 years old. I
live in Sioux City, California. My question is: Why are the
stars in the sky?
Ezra: My name is Ezra. I'm five years old. I live in Georgia,
why why are there so many stars in the sky?
Zoe: Hi, my name is Zoe. I'm seven years old, and I'm from
Sydney, Australia. My question is, why is there stars in the
sky?
Talia: Well, a big thing is, you know, the the reason those big
gas clouds start collapsing down in the first place, it's
gravity. Frequently, if you have a question about why something's
happening out in space, the answer is going to be gravity.
It's it plays a huge role in how things operate out in space. So
you have gravity causing these gas clouds to collapse down, and
they would just keep collapsing down further and further and
further, but when they start making heat inside themselves,
when they start to heat up, that starts to push outward. So you
have gas, the gravity pulling everything inward, and this
pressure from heat inside pushing everything outward. And
kind of when it comes to a balance, that's where you're
going to get a star, so our sun you can think of as being a
constant war between these two forces. The gravity of all the
mass, all the stuff that's inside the sun wants to pull
everything in towards its center, but it's also making all
that heat and light that we enjoy here on Earth, and that's
sort of trying to push everything outward. Now these
two forces are in balance, so we have a nice healthy star.
Eventually, stars do reach a point where they start to run
out of fuel, and one of those forces wins. But we've got
another 5 billion years or so before that happens with the
sun. The sun's going to be a healthy star for a very long
time.
Jane: Do we see it happening? Can we see it with our own eyes
when that happens to other stars?
Talia: Well, sort of. You can't when it's not something that's
happening all the time. But there are stars you can look out
at, and for instance, one of them is in the constellation
Orion. There is another one in the constellation Scorpius,
which is up in the sky tonight, doesn't matter actually which
hemisphere you're in. You can see it from the northern
hemisphere or the southern hemisphere, and it's the heart
of the Scorpion is a red star named Antares, which is it's so
red that the name Antares roughly means not Mars. Just to
make...
Jane: Because Mars is also called the red planet.
Talia: Yes. So Mars also looks red in the sky, and the star
Antares also looks red because this is a really large star that
is much farther along in its life than the sun is, and it is
approaching the end of its life.
Jane: And we're already sort of seeing into that process.
Talia: Yes. So it's at the the reason it looks red in the sky
is because it is approaching this sort of end stage, this end
game in its life, and it's starting to fuse different types
of gasses in its core, and it's really heating its core up, so
it's actually making the star swell up into a giant, and that
makes it also turn red, and eventually it's not going to be
able to keep that up anymore. And that's when the gravity's
going to kick in, and that's when that star is going to
explode in a supernova, which is something that only the biggest
stars do. But Antares is very large.
Jane: Are we going to be alive to see that?
Talia: Probably not. This is going to happen sometime in like
the next 100,000 years or so, which is a very short time in
the period of a star, like in the lifetime of a star, but not
so much the lifetime of a person.
Jane: All right, fine. Well, I won't get hopeful then that I'm
going to see it. So you mentioned that Antares looks
red, and some of the questions we've gotten are about the
colors of stars.
Eliza: I'm Eliza. I'm from Missouri, and I'm seven years
old. And my question is, why are stars white?
Willow: My name is Willow, and I'm four and a half years old,
and I live from British Columbia, Coldstream. And my
question is why are stars white?
Reed: My name is Reed. I'm six years old. I live in Exeter,
California, and my question is why are some stars blue and some
stars red?
Talia: Excellent question. It's all about the temperature of the
surface of the star. So, you know, here on Earth we usually
use red to mean hot and blue to mean cold. But it's kind of the
opposite when you're talking about stars. The redder stars
have cooler surfaces. Now, you know, I say cooler. You can go
up and give it a hug. We're still talking several 1000
degrees, but the reason Antares is red is because those outer
layers have puffed up so far away from its super hot core
that they've cooled off and they've turned red. The blue
stars; those are the in blue and white. We tend to say stars are
blue or white when they're at this stage. They're the biggest
and the hottest. They're they're big stars right in the prime of
life. Antares was probably a blue star before it began to
enter this end stage of its life. So we do have several of
these blue stars visible in the summertime sky. In fact, if
you're looking up at your summertime sky from the northern
hemisphere, one of the brightest stars you can see is the star
Vega, and Vega is a sort of a bluish white color because it's
a young hot star.
Jane: If we're looking up right now here in the planetarium, can
you orient me and show me where it would be and what
constellation it might be a part of.
Talia: Absolutely. It's part of the constellation Lyra the lyre,
which means it's a it's like a harp. Although I gotta say this
is one of the constellations that really doesn't look very
much like what it is supposed to be. And right now we're looking
at about 9:00 on August 7, and it's almost straight up. It's
very close to. It's part of the summer triangle. It's what that
I was talking about before, those three bright stars that
appear in the summertime sky. Vega is the brightest of the
three, and at 9:00 on August 7, it is almost straight up.
Jane: Is it the one that looks like it's part of a fish?
Talia: It does look like it's part of a fish. Yep, that's it.
Jane: Yeah, it looks like a fish to me. I'm not seeing a harp.
Talia: No.
Jane: After the break, more secrets of the night sky, like
why do stars twinkle and how do you navigate using the stars if
you're lost? Stay with us.
This is But Why. I'm Jane Lindholm. Today, I'm with
planetarium educator Talia Sepersky at the Museum of
Science in Boston. We're learning all about stars and how
they make up these imagined shapes called constellations, as
well as how stars form. And to do it, we're looking at a
projection of the night sky in Boston, Massachusetts, which is
in the northeastern part of the United States, on August 7,
which is the day this episode comes out.
Triti: Hi, my name is Triti, and I'm seven years old, and I'm
from India. My question is, why do stars twinkle?
Amelia: Hi, my name is Amelia, and I'm eight years old, and I
live in New Jersey. Why do stars twinkle?
Oddaya: This is Oddaya from Israel. I have a question. Why
do the stars twinkle?
Josie: Hi, my name is Josie. I'm six years old. I'm from Shingle
Springs, California. How do stars sparkle?
Esther: My name is Esther. I'm from Warsaw, Poland. I am five
years old. Why do stars twinkle?
Talia: Ah, the fun part of that is they're not actually
twinkling. You know, twinkle, twinkle, little star, the the
classic song. They're not twinkling. Our atmosphere is
making it look like they are. So when starlight reaches your eye,
so you can see the star when the light from the star gets all the
way through space and reaches your eye. But the last step
before it reaches your eyes, it's got to get through Earth's
atmosphere, the air around us, and that can actually change the
light a little bit. For one thing, especially in the summer
when it's really really hot, air moves a lot when it's really
really hot, and it can make the starlight that's coming through
the atmosphere look like it's wiggling, and we see that as a
twinkle. So when we're actually seeing you know stars twinkle
twinkle little star, the star is not doing that. It's Earth. It's
the air around us playing tricks on our eyes.
Jane: But I can remember as a kid being told, if you see
something that's not twinkling, it's a planet, and if you see
something that is twinkling, it's probably a star. So what's
the deal with that, or is that just wrong?
Talia: Nope, that is a pretty good rule. The it has to do with
the fact that starlight is coming from something so far
away from us that even though a star is actually a huge,
enormous object, it's so far away from us that it essentially
looks like a dot. We call that a point source, but the point is
that it it looks like it's coming from a single spot,
whereas those things that don't look like they're twinkling look
like stars that aren't twinkling. Those are planets in
our own solar system, and they're not nearly as big as the
stars, but they're so much closer to us that they're more
like little circles than single points, and that actually
affects the way the light comes through Earth's atmosphere, and
it's why planets, unless it's a really hot day and the
atmosphere is really dancing around, planets are not going to
appear to twinkle the way that stars do.
Georgia: Hi, my name is Georgia. I'm four years old. I live in
Toronto, Canada. Why do we see stars at night?
Jane: Why do we only see the stars at night? We can see the
moon during the day sometimes.
Talia: We can, and the reason we can see the moon during the day
is because it's also quite close to us. It is less than 250,000
miles away, which I know sounds like a huge distance, but that
is right next door when it comes to things in space. These stars
that you see at night-they are up during the day. They're all
still shining. They don't switch off during the day, but they are
really, really, really far away from us. And the sun, even
though it's a lot of these stars that you see at night, are
bigger than the sun. But the sun is so close to us; it's only 93
million miles away, which yes is a short distance when you're
talking about distance to a star. It's like a giant
spotlight shining right in your face. Now, if you've got a
humongous spotlight right in your face, you might be able to
see something that's right next to you, like the moon, but
you're not going to be able to see anything else, and so we
really can't see these other stars because our sun is just so
bright in our daytime sky. That's why we only see them when
the sun's not in the sky.
Jane: Will you tell us about another constellation before we
move on to some other questions? Maybe one of your favorites.
Talia: Absolutely, actually, one of my favorites is the third
corner of the summer triangle. So we talked about Aquila the
Eagle, which has the the star Altair in it, and we talked
about Lyra the Lyre, which has the really bright star Vega in
it. The last corner of the triangle is the constellation
Cygnus the Swan, which I like because it is actually one of
the few constellations that looks like what it is supposed
to be. It looks like a swan in flight. It's got a long body and
a long neck, and then it's got the wings spread out to either
side. And then behind the wings is its little tail, and that
tail star is Deneb. And the eye star, the one that's in the
middle of the triangle. The eye of the swan is Alberio, and
those two stars are both really interesting. Alberio, if you
ever get a chance to look at it through binoculars or a
telescope, is actually two stars, and they are very
different colors. They're two stars that are very different
colors. One of them's very very blue, and one of them's much
redder. And then Deneb, the tail of the swan-that is one of the
most distant stars you can see with your eyes. It doesn't look
super big and bright, but it's actually really huge, really,
really, really ridiculously huge, and really, really, really
ridiculously bright. It's just also really, really far away.
Jane: Why do you like that one? Just because it looks like a
swan, or because of some other reason?
Talia: I mean, for that one, it's because I like that it
actually looks like what it is supposed to be. I also always
love if you look at the constellations of the Summer
Triangle, Cygnus and Aquila, the Swan and the eagle-they look
like they're flying at each other-and I always ask guests in
the planetarium who they think is going to win if there's a
fight between the swan and the eagle. And everybody always
picks eagle, and I say that means everybody is severely
underestimating how mean swans are.
Jane: Yes, totally. So, what we're looking at right now-the
whole time we've been talking, all of these stars have been in
the same place. But if we were lying down in a field watching
the stars, we might not notice at first. But over time, we
might see that they have kind of changed position in the sky from
where we were looking at them in the past.
Lucy: My name is Lucy. I live in Oakland, California, and I am
eight years old. My question is: How do stars stay in space, and
do they look like dots, or do they look like the shape of a
star?
Noa: Why do the moon and stars look like if they're following
us, but they're really just staying in one spot?
Jane: Do stars move, or are they staying in one place and we're
moving, or what's happening?
Talia: Well, there's sort of two answers to that question. If
you're talking about over the course of like a night, you do
see the stars appear to move across the sky, and that's not
because the stars are moving. That's because Earth is moving.
Earth is spinning or rotating. It takes about 24 hours for
Earth to rotate completely once. That's why we have a
24-hour-long day, and because of that, that's why the sun appears
to rise in the east and set in the west. It's same with these
stars; they're going to appear to move across the sky, and that
is all down to the way Earth is spinning. Now that said, the
stars do move. They are all moving through space. They're
all moving through the Milky Way galaxy. They're just moving on
really long timescales. It's not something you're going to notice
from night to night, or year to year, or even lifetime to
lifetime. But if you look over the course of a few thousand
years, you definitely see the stars appear, some of the stars
appear to start to change their position compared to the other
stars. So the constellations of say somebody who was living
10,000 years ago aren't going to be exactly the same as the
constellations you're going to see today because the stars will
have moved a little bit, but again, that's not what's
happening on a day-to-day basis. That movement is not actually
the stars. That's us.
Jane: So it didn't. I mean, not they're not moving enough though
that the serpent really looked like a serpent, and now it
doesn't.
Talia: Oh no, that's just down to those ancient Greeks having a
really active imagination.
Max: Hi, my name is Max, and I'm eight years old. I live in
Flint, Michigan, USA, and my question is: Why is the North
Star always facing north?
Talia: That is an excellent question, and it's a-it's
actually has nothing to do with the star itself. So the North
Star, or what we now call the North Star, Polaris, is its
official name. It has to do with where the star is in space. So,
if you've ever seen maybe a globe of the Earth in your
classroom, and there's a stick that runs right through the
center of the Earth, we call that the axis. If our real Earth
had a stick running through it, and that stick came out of the
North Pole, it would be pointing at Polaris, so Polaris itself
isn't a particularly remarkable star. It's not very bright, it's
not particularly interesting looking. It's just a normal
star, but it sits almost directly over Earth's north
pole, and that means that when Earth is spinning and all of
these other stars are appearing to move, the North Star,
Polaris, really just isn't moving. It's kind of like if you
spun in a circle, everything around you would appear to be
moving. But if you looked straight up, the spot on the
ceiling above you would appear to hold still. So Polaris is
just sitting in a particularly useful spot. And the funny thing
is, if you want to go crazy, if you go wait long enough, the
North Star isn't going to be the North Star.
Jane: Because of that star movement you talked about?
Talia: Nope, this one's down to Earth again. Earth actually
wobbles like a top over the course of about 26,000 years. It
wobbles in a complete circle. So again, this is a very long, slow
process. But remember, I was talking about the star Vega in
the constellation Lyra earlier, 13,000 years ago, Vega was the
North Star, and it will be again in another 13,000 years. So
right now, we have a nice bright star sitting pretty much right
over to the North Pole. That's not going to stay the case. So
it's actually kind of cool that we are living in a point in
Earth's wobble where we have a North Star.
Jane: Well, you talk about where these stars are and and how we
sort of think of them in the night sky. And if you know the
North Star, then you know where North is. But we got a question
from Hannah, who says,
Hannah: How do you navigate the stars when you get lost?
Talia: So a big one is being able to tell which way is north.
So that's always a good thing to be able to find the North Star.
That will at least tell you which direction you're facing.
And then I believe I've never personally had to navigate by
the stars, You can also, if you know what stars are rising when
at different times of the year, and they used to have very, you
know, sailors, for instance, used to have very detailed
charts saying what rose when at different times of the year.
That can actually help you figure out your longitude, how
far east or west you are. If you've got really precise clocks
and really precise charts, knowing say if you're in, you
know exactly when a star appears to rise in the east on this day
in London, and then you know what time of day it appeared to
you wherever you are? If you have a really accurate clock,
you can then use that to figure out how far east or west of
London you are. It's pretty complicated, and I'm really glad
we invented the GPS.
Jane: I guess also if you let's say you took a long nap and you
woke up and you were like, "Have I been asleep for three months
or seven months, if you knew where you were and you saw what
was rising when, you could be able to tell maybe what even
what day or what month it is.
Talia: Yes, for instance, I always know that we're
approaching the beginning of spring because the constellation
Leo starts appearing in the east when the sun sets. Leo is only
in that spot in the sky at that time of day in like late
February when it's starting to be towards springtime, and
that's always exciting for me because I'm always ready for
winter to be over. I should say it's springtime in the northern
hemisphere, not for the southern hemisphere. And similarly, you
know, I can tell how far. We are into summer by how high the
summer triangle is when the sun sets. You know it's not precise.
I can't be like, oh, it's it's 6:03 p.m. but I can tell roughly
what time of year it is from that.
Jane: So, Talia, you don't even have a calendar at home.
Probably, you just navigate by the stars, the stars to see. Oh,
I know what day it is today. I have to go to work early because
I saw when the stars rose last night.
Talia: I can't do that. But there were ancient cultures that
I think could do that. They tracked the stars so precisely,
and there's even you know ancient architecture, ancient
monuments built around these very precise appearances of
specific things in the sky at specific times of the year, they
were truly great astronomers.
Jane: Yeah, that's kind of amazing to think about how how
precise they could get it on a certain day to have the sunlight
stream through, you know, kind of a frame of stone or something
like that.
Talia: Absolutely, and there I know there are things that are
built around you know the the time that the Pleiades rise on a
specific day. The Pleiades is a little star cluster that we see
in like the winter time sky here in the north, and there are
things built around when that appears at specific on specific
dates and or the orientation of the Milky Way relative to
different things on different dates, like people tracked this
stuff very, very precisely, considering they didn't have any
telescopes or any tools like that to work with.
Jane: The Pleiades is one of my favorite constellations. I love
going out in the winter and seeing it, and to me, it looks
kind of like a kite.
Talia: I mean, I always see it look like a little, little,
little, little dipper, personally.
Jane: Yeah, I can see that too. Speaking of the dipper:
Dane: My name is Dane and I live in Spokane, Washington. How does
the Big Dipper appear?
Jane: How does the Big Dipper appear?
Talia: Oh, I always think it looks like a pot that has a bent
handle. So there are seven stars in the dipper, and four of them
make up the pot, and then three of them make up the handle. And
the handle has a bend in it; it has kind of an arc in it. So I,
you know, I've heard people call it a big spoon or things like
that. I think it looks like a cooking pot with a bent handle.
Jane: What's the difference between the Big Dipper and the
Little Dipper?
Talia: Oh, many things. The Big Dipper, first of all, is made of
much brighter stars. So if you're looking, you see it, and
you're not sure if it's the Big or the Little Dipper, it's the
Big Dipper. It's much, much brighter than the Little Dipper,
and their handles actually curve in different ways. So the Big
Dipper has a handle that curves up, and the Little Dipper kind
of has a handle that curves down.
Jane: So, here on August 7 in the planetarium, as we are
looking at the sky tonight again, this is the Northern
Hemisphere summertime, and we're looking from the perspective of
New England. But some of the Northern Hemisphere stars are
going to be seen in a lot of different places in the Northern
Hemisphere. This is may look fairly similar if you're in the
Northern Hemisphere. How would you advise us to start
stargazing? Because as you told us, there are so many stars in
the sky; it can feel a little intimidating or overwhelming to
know how to start thinking about stargazing at night.
Talia: I like to find one or two patterns that I can find fairly
reliably, and then use them to sort of learn the sky around
them, and then you can use those the the sky around them as
markers for figuring out you know what's beyond that. So, for
instance, the Big Dipper is a good one because the Big Dipper
you can use to find like if you follow the direction that the
handle arcs and you keep going, you can find the constellation
Bootes directly under the Big, well, the Big Dipper is part of
the constellation Ursa Major. Directly under the bear is Leo
the lion. The bear is standing on the lion's back.
Jane: And Ursa means bear. So Ursa Major is Big Bear.
Talia: Yes. So Ursa Major, Big Bear, and Leo is the lion. So
the way they're positioned in the sky, it looks like Ursa
Major, the bear, is standing on the lion's back. And you know,
for instance, if you can find, if you can use the handle of the
dipper to find Bootes, the herdsman. I use Bootes to find
the Northern Crown, which is right next to it. So I can use
the Dipper to find one thing, and then use that thing to find
another thing. So some good markers to use. Like I said, the
Big Dipper is a good one. If it's summertime, I like to use
the summer triangle. If it's winter time, I like to use the
constellation Orion, especially his belt. His belt is very handy
for pointing at things. So that's my advice. Find one or
two, two or three patterns that you can find pretty reliably,
and then use them to learn the sky immediately around them, and
then you can use the things immediately around them to find
even more things, and you'll gradually learn the whole sky.
Jane: And if you live in a big city where there's a lot of
tall, lit up buildings and car traffic and streetlights, that
doesn't mean you can't see any stars. Talia says when the
planets are in the visible part of the sky, you'll likely be
able to see them because they are very bright. And while you
might not be able to see entire constellations, you could still
spot a few really bright stars within those constellations.
Plus, many cities have museums or universities with either
planetariums or telescopes or both, and you might be able to
visit one. Okay, but what if you live in the southern hemisphere,
in a place like Australia or Chile or Botswana, and you have
been patiently listening to all this talk about the summer sky
in the northern hemisphere? It's true, the sky looks really
different depending on where you are, and the southern and
northern hemispheres have particularly different
constellations and celestial seasons. Well, we haven't
forgotten about you. I asked Talia to take us to see the
night sky in the southern hemisphere on August 7.
Talia: Absolutely. Let me go. Let me bring us to Australia.
Why not?
Jane: Woo! This is a very fast flight.
Talia: Yes, we are now in Australia. We are looking at,
and because the sun is setting earlier, we are now looking at
the sky the way it would look at about 7:00 and we've got a lot
of constellations I'm not that familiar with because I'm not as
familiar with the southern sky.
Jane: But some of them are similar. I'm seeing some of the
same constellations.
Talia: Yep, I can still see Aquila, the eagle. I can see
Lyra the lyre, and I can also see some really cool
constellations like the Southern Cross that I don't ever get to
see in Boston because I live too far north. Oh, and nice and
high. I should point out, right almost directly overhead from
Australia at 7:00 on August 7 is Scorpius, the scorpion with that
bright red star Antares at his heart.
Jane: And that kind of to me looks like a J, like a wonky J.
Talia: Absolutely, a J. It's supposed to be the curl of the
Scorpion's tail, but I know, for instance, if there are any fans
of the film Moana listening to this, there were Pacific Island
cultures that referred to it as Maui's fishhook, for instance.
Jane: And you could see that in New England too, but it was much
much lower in the sky when we were looking in the northern
hemisphere.
Talia: Yes, so you can see all of Scorpius from New England,
but his tail barely the bottom of his tail barely clears the
horizon. Now we're in Australia, and the whole scorpion is right
overhead.
Jane: I want to point out two other constellations before we
go. One is to me what looks like a kid, maybe with no arms,
kicking a soccer ball.
Talia: Is it the one that's right next to Scorpius? Yeah. So
that one, I always see a teapot with that one.
Jane: See, I love that we can see different things.
Talia: That is the constellation Sagittarius, the the Archer, and
that's actually the direction of the center of the Milky Way. And
you can see that from New England as well. Again, it's
going to be quite low, but that's the direction that the
center of our galaxy is in.
Jane: And then there's another constellation. Well, actually,
it's a couple of constellations, and it's above the Southern
Cross, and one of them looks very much like an animal, maybe
a wolf or some kind of animal with four legs and a big tail.
And then there's another animal, maybe a person. I don't know,
but definitely some other kind of animal kind of looks like a
minotaur, and they look like they're in conflict.
Talia: Well, I can tell you that the one that looks like a
minotaur that is Centaurus. So it is it's a centaur.
Jane: That's what I was thinking. Yeah.
Talia: And then the one next to it is a wolf. That is Lupus the
wolf. So very good with your guesses, and Centaurus is
actually the location of the star system that is closest to
Earth. It is one of the two bright stars, sort of marks the
front feet of the Centaur, is Alpha Centaurus, and that system
has three stars in it, one of which is Proxima Centauri, which
is the closest star to Earth at only 4.25 light years away.
Jane: Oh, so you practically next door?
Talia: Yes, it's right in the backyard.
Jane: Talia, is there anything else that you think would be fun
for us to know as we start looking up at the sky and trying
to understand what's going on up there?
Talia: Yes, if you're looking at the sky on August 7, you should
come back out and look on August 12, because the Perseid meteor
shower is going to be peaking that night, and there isn't
going to be any bright moon to get in the way. And the great
thing about a meteor shower is you don't need any special
equipment to enjoy it. You just go find the darkest spot you
can, make yourself comfortable, lay back, let your eyes adjust,
and look for shooting stars that are actually pieces of a comet's
tail that got left in Earth's path, and we're plowing into
them, and they're burning up in Earth's atmosphere, and it's one
of the better meteor showers of the year.
Jane: Since we're talking about shooting stars, here's one last
question.
Jana: My name is Jana. I'm from Long Island, New York. I'm six
years old. Are shooting stars real?
Jane: Yes, shooting stars are real, but it's so magical to
watch them in real time. And if you blink, you might miss one,
or you see one and your friend doesn't, or your sibling sees it
and you don't. So, what is a shooting star if not magic?
Talia: Ah, it's a piece of space debris burning up in Earth's
atmosphere. So.
Jane: I mean, that doesn't sound quite as cool.
Talia: I don't know. Something from space tearing itself to
shreds in Earth's atmosphere sounds pretty cool to me.
Jane: Thank you so much for sharing this with us and helping
us get excited about the night sky. I'm really excited to go
out and start using your technique of just trying to know
a couple of things, and then knowing a couple things more by
using those constellations or those stars as my guide.
Talia: Oh yeah, always start small. I mean, the sky's not
going anywhere. You have plenty of time to learn it, and if you
want to just go out and just look up, and enjoy how beautiful
the night sky is, that is also a great way to be an astronomer.
Jane: And if you have any constellations that you see in
your mind's eye, will you draw us a picture of what
constellation you see? Maybe your adults can help you look up
which stars are in your constellation, and then you can
send the shape that you see, whether it's an animal or an
instrument or a toy, and send us a picture of what you've drawn.
I really want to hear what you would call your constellation
and what you think it looks like. Send it to
questions@butwhykids.org. Thanks to Talia Sepersky, planetarium
educator at the Museum of Science in Boston, for taking us
on a guided tour of the night sky. That's it for today. As
always, if you have a question about anything, have an adult
record you asking it on a smartphone using an app like
Voice Memos. Then have your adult email the file to
questions@butwykids.org. Our show is produced by Sarah Baik,
Melody Bodette, and me, Jane Lindholm, at Vermont Public, and
distributed by PRX. Our video producer is Joey Palumbo, and
our theme music is by Luke Reynolds. If you like our show,
we'd love it if you and your adults would give us a thumbs up
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helps other kids and families find us, and that helps us keep
going. We'll be back in two weeks with an all-new episode.
Until then, stay curious.