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muse
JULY/AUGUST 2017
®
TOTAL
SOLAR ECLIPSE
viewing guide + much more
musë
muse JULY/AUGUST 2017
Volume
Volum
me 2
21, Issue 06
FEATURES
10
Ready, Set, Eclipse
An observer’s guide
by Meg Thacher
20 27 28 36 40
I Saw the Eclipse— There She Blows! So Long, Saturn The Truth A Mission to
from Space! Jupiter’s moon Cassini ’s mission is about Pluto Discover Our Past
Students launch a Europa is in the coming to an end. Why did it lose its One special asteroid
high-flying project. news. by Rachel Zimmerman “planet” status? may hold the key.
by Nick D’Alto by Mara Johnson-Groh Brachman by Charles C. Hofer by Stephanie M. Bucklin
CONTENTS
DIRECTOR OF EDITORIAL James M. “Bosun” O’Connor
EDITOR
CONTRIBUTING EDITOR
Johanna “Sunporch” Arnone
Kathryn “Tsunami” Hulick
DEPARTMENTS
DEPARTMENTS
COPYEDITOR/PROOFREADER
2
Meg “Sunflower” Moss
ART DIRECTOR Nicole “Gesundheit” Welch Parallel U: “Pigmentamorphosis”
DESIGNER Pat “Sunfish” Murray by Caanan Grall
DIGITAL DESIGNER
RIGHTS & PERMISSIONS
Kevin “Unsung” Cuasay
David “Sundae” Stockdale
7 Muse News
by Elizabeth Preston
BOARD OF ADVISORS 16 Infographic:
ONTARIO INSTITUTE FOR STUDIES IN EDUCATION,
UNIVERSITY OF TORONTO
Anatomy of a Star
Carl Bereiter by Meg Thacher
ORIENTAL INSTITUTE, UNIVERSITY OF CHICAGO
John A. Brinkman 18 Science@Work: Marla Geha
NATIONAL CREATIVITY NETWORK by Peg Lopata
Dennis W. Cheek
COOPERATIVE CHILDREN’S BOOK CENTER, A LIBRARY
24 Mini-Myth: Hey, Bring
OF THE SCHOOL OF EDUCATION, UNIVERSITY OF Back Our Sun!
WISCONSIN–MADISON
K. T. Horning by Carrie Clickard
FREUDENTHAL INSTITUTE
Jan de Lange
32 Photo Op:
FERMILAB The Cassini Gallery
Leon Lederman by Rachel Zimmerman Brachman
UNIVERSITY OF CAMBRIDGE
Sheilagh C. Ogilvie 45 Do the Math: Planet Search
WILLIAMS COLLEGE by Ivars Peterson
Jay M. Pasachoff
UNIVERSITY OF CHICAGO 47 Your Tech
Paul Sereno by Kathryn Hulick
48 Last Slice
by Nancy Kangas
MUSE magazine (ISSN 1090-0381) is published 9 times a year, monthly except for combined
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YOUR TURN
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Citizen Science
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Editorial office, 70 E. Lake Street, Suite 800, Chicago, IL 60601. July/August 2017, Volume 21,
Muse Mail
Number 06, © 2017, Carus Publishing dba Cricket Media. All rights reserved, including right of
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compliance with the Children’s Online Privacy Protection Act, please visit our website at cricket-
35 Q&A
media.com or write to us at CMG COPPA, 70 East Lake Street, Suite 800, Chicago, IL 60601. by Lizzie Wade
Photo credits: C - REUTERS/David Gray; TOC - REUTERS/Yuriko Nakao; 5-6 CPdesign/Shutterstock.
46 Contest: Inventor to
com; 5 (RT) CebotariN/Shutterstock.com; 6 (LT) Jennifer Davis, (LB) Laura Dinraths/Shutterstock.
com; 7 (TC) Sumukha J. N; 8 (RT) ALEXANDR SOLDATOV/Shutterstock.com, (LC) Korotova Liudmyla the Stars
/Shutterstock.com, (RB) Microgen/Shutterstock.com; 9 (RT) Kurt Hickman, Stanford University,
(LB) Yu Chen; 10-11 Allexxandar/Shutterstock.com; 12 (LT) Michael Zeiler, greatamericaneclipse.
com, (RC) NASA; 13 (LT) Rolf Nussbaumer Photography / Alamy Stock Photo, (RT) RGB Ventures
MS. ACORN
/ SuperStock / Alamy Stock Photo, (LB) Arne Danielson/NASA; 14 (LT) © Jay M. Pasachoff, (RB)
Photo by Deborah D. Pasachoff; 18 (bkgd) ESA/Hubble & NASA, (BC) Marla Geha; 19 (BC) Eduard
Moldoveanu/ Shutterstock.com; 20-21, 20 (RB), 21 (LT), (RB), 22 (RC), (RB) Eclipse Ballooning
Project, (LC) MSU photo by Evelyn Boswell; 20-23 (bkg) Oleg1969/Shutterstock.com; 27 -
NASA/ESA/K. Retherford/SWRI; 28-29 NASA/JPL-Caltech/Space Science Institute; 30 (LT) NASA/
Jet Propulsion Laboratory, (RT), (LB), (RB) NASA/JPL-Caltech/Space Science Institute; 31 (RT)
NASA/ Jet Propulsion Laboratory-Caltech; 32 (TC) NASA/JPL-Caltech, (RB) Morphart Creation/
Shutterstock.com; 33 - NASA/JPL-Caltech/Space Science Institute/Kevin M. Gill; 33 (LT), 34 (TC),
STRONGLY RESEMBLES Cate’s
(LB) NASA/JPL-Caltech/Space Science Institute; 34 (RB) REUTERS / Alamy Stock Photo; 36 - NASA mom Issa Pine
/ Johns Hopkins University Applied Physics Laboratory / Southwest Research Institute; 37 (BC)
Santhosh Varghese/Shutterstock.com; 38 (RT) Charles Hofer, (LT) David Roland/Shutterstock. HEIGHT 5'9"
com, (LB) Catmando/Shutterstock.com; 39 (TC) NASA; 40 - Jurik Peter/Shutterstock.com; 41 (RT),
42 (LC) PHILIPPE MOUCHE, JONATHAN JACOBSEN AFP/Newscom; 41 (RB) Vector Tradition SM/ AGE N/A
Shutterstock.com; 42 (RT) NASA/Joel Kowsky, (RB) Lockheed Martin Corporation; 43 (RC) NASA/
Kim Shiflett, (TC) NASA/GSFC; 44 (TC) NASA’s Goddard Space Flight Center/Conceptual Image FIRST POWERED UP 1983
Lab, (LC) University of Arizona/Symeon Platts, (RC) NASA/Kim Shiflett; 45 (LT) NASA/JPL-Caltech;
46 (LT) Ninya Pavlova/Shutterstock.com. INTERESTS Education, human
Printed in the United States of America.
knowledge, the Mnemosyne
1st printing Quad/Graphics Midland, Michigan June 2017
community, data storage,
practical jokes
From time to time, MUSE mails to its subscribers advertisements for other Cricket Media
products or makes its subscriber list available to other reputable companies for their offering ONCE SAID “The mothership
of products and services. If you prefer not to receive such mail, write to us at MUSE, P.O. Box
6395, Harlan, IA 51593-1895. won’t be returning for me.”
PARALLEL U CAANAN GRALL 2
CITIZEN SCIENCE CAANAN GRALL
ts r
s e e n thusias M e g Thache
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d S t a tes ecl a sa c h th e m ap on p ay
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INTO THE THAT WAS ONE
I CHATEAU OF FUN SUN PUN RUN
HEAR THE MOON GUYS.
WHO’S SURE THE PHASES PLEASE!
READY FOR A TO ECLIPSE ARE SET TO
TOTALITY AMAZING ANY OTHER PLANS STUN!
EXPERIENCE? YOU MIGHT HAVE
TODAY.
3
Cricket Crossover Event
Hello Earthlings, aliens,
Muse Mail
parakeets, and other strange
creatures!
I am a Gravity Falls fan, a
parakeet enthusiast, a theater
kid, the overlord princess of
violin, and a rather devoted Muse
reader. If you get Cricket, you
may know me on the Chatterbox
as Abigail S. Hi, CBers! Oh, this
isn’t the time? Right. Anyway.
Besides the fact that Muse is
amazebubble and I would like
to express my Parallel U fangirl-
ness, I am writing to suggest
something. During the time of
the old Muses (RIP Kokopelli),
there was the [online] Muse
Townhall, which I enjoyed
going on and I miss now. It
would be awesome if y’all could
resurrect it! I love how Muse is
educational and sciencey and
Fan art by Hugh P. B. interesting and well written, so
ILLUSTRATION it was really fun to discuss the
of the MONTH articles on the Townhall with my
An Artist by Any Other Name fellow science nerds!
I would like to start off simply by saying If you decide to toss this letter
thanks. Your magazine is marvelous, or magnifique, as they into the FMP, no dragons will
say in the land of cheese (France). May I ask some questions come and eat you. No potatoes
will leap onto your heads and
concerning Aarti, O, Cate, Whatsi, and Ms. Acorn? (Using my do painful jigs in tap shoes. No
magical abilities, I can see you shaking your head yes.) OK so multicolored bunnies shall invade
number one: does Cate’s hair naturally grow like that or does your personal space. All that will
she style with mousse? (Of course, I could ask the same ques- happen is that one 12-year-old
tion about Whatsi.) living half in Southern California
Number two: if Ms. Acorn is only a hologram, why is it that and half in her imagination will be
she clearly has a shadow? I mean, a hologram is a projection a bit disappointed.
of light concentrated to form a visual 3D object. If Ms. Acorn —ABIGAIL S. / age 12
is truly a projection of light, she would be completely intan-
gible, however, she still manages to do things like hold objects
standing on solid ground and HAVE A SHADOW! Let’s Pretend
Finally: amazing coincidence! You have abbreviated hot pink Fair tidings! I’m Evan. So,
bunnies to “HPBs,” and guess what else HPB stands for? Me! My I came up with this method
initials are H.P.B. Before you ask, I am NOT making this up. pretty much about (nothing
—HUGH P. B. special) TELEPORTATION! It
P.S. Is Ms. Acorn married? all starts with atoms. Nucleus
and electrons. Let’s pretend
Huge props for your artwork, Hugh! I’ve heard Ms. Acorn’s the electrons are the size of
an apple. The nucleus would
name is actually an acronym, but I’m not sure what it stands
be some thousand feet away.
for. (She looks real to me too!)
This has puzzled scientists
—AARTI
4
for years about what the
space between the electrons and
nucleus is. This could be a fourth
source of matter. One day a little
super smart birdie came along
and told me if wormholes could
be a source of transportation
that would be revolutionary, but
they could only be stabilized
with something that’s neither
solid, liquid, nor gas. That’s why
I’m here. To tell you if that space “Kittens must be
is matter, teleportation could be petted, or they
a reality. will remain wild
FOREVER.”
—EVAN / age 9 1/2 / Minnesota
P.S. If it is a fourth source of
matter, please contact the
government!
Thanks for writing nice) and the dragon with
I Love Cats
Evan. I believe
I love Muse and cats! I have gray swirls. I’m just a plain
scientists call gray dragon. I am NOT an
two cats, Shadow and Blondie.
plasma the fourth Earth dragon. I’m from planet
I get three magazines: Muse,
state of matter. The sun is a Tripico. It’s millions of light-
Cricket, and Catster.
great big ball of plasma, for years away (trust me), so we
I think you should write
instance. Does that help with can’t reunite. Now that I think
an article on the science of
your inventing-teleportation about it, that’s probably why
cats. Here are some facts to get
project at all? I got my Muse so late last
you started:
—WHATSI time. Anyways, I’m going to
Cats have three eyelids.
Kittens must be petted, or be late for the tea party with
they will remain wild FOREVER! the hot pink bunnies.
Edited for Space (but A tiger’s skin is striped like —THE ANONYMOUS JAY
Not Sense) its fur. P.S. Cate, can you somehow
On a scale of one to ten, If there are hot pink bunnies visit me? (You’re my favorite!)
what’s your favorite color of at Mnemosyne, maybe there
the alphabet? Mine is square should be electric blue cats too. Thanks you
. . . but many people who have Please don’t throw this letter two—I’m blushing.
taken the survey choose a into the fan mail pit. Oh, and by Vanessa, you’ll be
strange creature called a WHAT the way my favorite Parallel U the first person I tell
ON EARTH?! Never heard of it, character is Cate. if I spot an electric
have you? Look at the phrase —VANESSA V. / age 12 / California blue cat. That would be a thrill.
“fresh avocado.” What happens if And Anonymous Jay, I’d normally
you put the space here: FRE warn someone away from an
SHAVOCADO? Try saying it out HPB tea party. They’re notorious.
loud. It will seriously make you Just a Plain Gray Dragon But you should be able to hold
laugh really hard. Cate, do you Hello human beings! This your own.
have a favorite time? IS MUSE cannot be thrown in the FMP!!! —CATE
EDIBLE?!!? There ya go. I said I have been trying to contact
it. Now: IF YOU THROW THIS my fellow dragons. You see, Something to say?
IN THE FAN MAIL PIT, I WILL in a previous Muse, there Send letters to Muse Mail,
SEND AN ARMY OF POTATOES was the leafy sea dragon and 70 E. Lake St., Suite 800,
Chicago, IL 60601,
TO ATTACK MUSE HQ !!! GOT then the dragon with orange or email them to
IT? Great! *evil grin* >:) stripes (I know a dragon who muse@cricketmedia.com
—THE TOTALLY AMAZING FOX has polka dots but she’s really
5
currently at level 2 (small hits and doughnuts; Craaw the
and pushing), and trying to get muse of poetry; Bo, the muse of
to level 3, where you can hit reading; and Aeiou, the muse of
Muse Mail
as hard as you want. So I am technology. There were others,
practicing dishing out hits and but my old magazines were
receiving them. thrown out.
—JULIANNA D. (LOVE POTION #9) (5) Starfishes are not fishes and
/ age 13 / Alberta, Canada have no brains.
(6) And finally, the most
important answer: ???????????????
???????????????!!!! Do not forget
this or you will ?????????!!
Seven Answers to
(7) FROM, THEO / age 12
Questions Unknown
I know you new people have
some questions. Well, I have
all the answers. Here they are:
(1) 42. We don’t know the Oculus Engineer
question yet. Your magazine is the BEST!
(2) A healthy woodchuck can And when I say best, I mean best
chuck about four logs per day. in the whole stinking multiverse
Go Wipeouts! (3) The HPBs, or hot pink of magazines! It seems like
I was so excited when bunnies, were a tactic employed whenever I get into something
I found a roller derby by the original Muses during the scientific, you publish a whole
article in your magazine! cat-dog war. They worked like issue on it. When I got into
Never before have I seen an this: if there was any statement relativity, you published an
article about roller derby in about the superiority of cats issue on it. When I got into
a magazine before. I actually over dogs or vice versa, it would sustainable cities, you published
play on a junior roller derby be replaced by hot pink bunnies. an issue on it. When I got into
team so it was pretty cool (4) The original Muses were: virtual reality, you published
to see the sport that I play Kokopelli, the muse of pie a whole issue on it. What are
in a magazine! I am in my throwing and trickery; Chad, you doing? Stalking me with
fifth season of junior derby the muse of science; Urania, HPBs? When you published the
with the Lethbridge, Alberta, the muse of astronomy; October 2016 issue, it got me
Windy City Wipeouts. I am Feathers, the muse of farming into virtual reality even more.
It got me into VR so much that
“Starfishes are not fishes I rallied all my grandparents
and have no brains.” and parents into getting me an
Oculus Rift for my birthday. It’s
SO COOL! I truly do think that
it’s the future of entertainment,
sports, and so much more. Also,
could you guys please do an
issue on engineering? It’s what
I want to be when I’m older.
Maybe you could do a few
engineering challenges? Thanks.
—THAT DUDE FLYING AROUND IN
VR / age 12 / Florida
P.S. O’s my favorite muse.
Dude! You’re my
favorite reader. Or
one of my favorites, at
least. See you in VR!
—O
6
Muse News
text © 2017 by Elizabeth Preston BY ELIZABETH PRESTON
ACCIO ARACHNID
Harry Potter and the
Sorting-Hat Spider
I
n a forest in southwestern India, researchers discovered a
new species of spider. The little brown critter has spiny legs
and a pointed back that looks like a dead leaf. This helps it
stay camouflaged during the day. But the spider’s odd One of
shape didn’t only remind the scientists of a leaf. They also
thought it looked just like the “sorting hat” from the
these stories is
Harry Potter books. FALSE. Can you
In J. K. Rowling’s series, every new student arriving at spot which one?
wizarding school has to put on this magical hat. Then the hat The answer is on
announces which of four houses the student belongs in. The page 45.
hat’s original owner was school cofounder Godric Gryffindor. So
the scientists named the new spider Eriovixia gryffindori, in honor
of the books they love—and the magical world of real-life bugs.
PHYSICS
Solar Flair
Muse News
WISH YOU were a little taller? If you live in the
path of this summer’s solar eclipse, you can take
advantage of a neat light-bending effect to give
yourself a boost.
People living in some parts of the United
States will be able to witness a total solar eclipse
on August 21. In this rare event, the moon
briefly blocks our view of the sun. Just before the
sun is totally covered, a phenomenon called the
Gregory-Jordan effect will occur. The last weak
sliver of sunlight, warped by passing through
Earth’s atmosphere, will cause objects to appear
vertically stretched. As a result, a photo taken at
exactly the right moment will make a person
look 13 to 15 percent taller. Get those selfie ANIMAL BEHAVIOR
sticks ready!
Why Did the Pigeon
Cross the Road?
. . . Because it didn’t care that there was a car coming!
City animals are often in danger of getting squashed
by traffic. But if they watch lots of cars, trucks, and buses
speed past, maybe they learn to keep their distance.
Scientists tested pigeons to find out if this is true. They
used birds that had grown up in a barn and never seen
traffic. First, the researchers put the pigeons in cages
next to a road and zoomed past them in a pickup truck,
over and over. Then they tested the birds in a virtual
traffic simulation.
The pigeons watched a video of a truck that looked like
it was about it hit them. Researchers measured how
quickly the pigeons got scared and flew away. Pigeons that
had been trained with a real truck were less afraid, not
more. So much for street smarts.
SPORTS
A Secret to
Faster
Swimming
USING COMPUTER models,
3D-printed plastic arms and
hands, and a wind tunnel,
researchers discovered that
freestyle swimmers can speed up
by slightly spreading out their
fingers. Spacing the fingers 10
degrees apart creates more drag,
or pull against the water, than
holding the fingers together.
8TECH DESK
Old Toy Gets a New Spin
A CENTRIFUGE (SENT-ruh-fyooj) is a
basic tool in medical labs. It’s a
machine that spins very quickly.
When doctors spin a tube of blood in
a centrifuge, the blood separates
into different components, like salad
dressing before you shake it up. This
lets doctors examine the blood or
test it for diseases. But these
expensive tools are hard to get in
some parts of the world. Now
researchers have come up with a
(very) cheap solution, based on a
classic toy.
The team got inspiration from a
toy called a whirligig or buzzer. It’s a
disk or button that spins on a loop of “paperfuge” holds tiny tubes on a toy for just a minute and a half can
string. Kids around the world have disk made of paper. When a user separate blood. The invention, which
played with these for pulls the handles, the disk spins at costs only 20 cents to make, could
thousands of extreme speeds—up to 125,000 become a practical tool for doctors
years. The new rotations per minute. Twirling the around the world.
PALEONTOLOGY
From Toothy to
Toothless
LOSING YOUR baby teeth younger dinos had a mouth
can be awkward. There are full of tiny teeth, they lost
gaps in your smile, your these teeth as they grew up.
mouth is changing all the Adult dinosaurs had no teeth
time, and biting into an apple at all. Instead, they had
Dad’s a is risky. But be glad you’re not smooth beaks.
vegetarian, but a dinosaur named The scientists think toothy
I’ll chomp lotsa Limusaurus inextricabilis. young dinosaurs dined on
things. After this animal lost its baby many different foods, while
teeth, it grew a beak. the beaked adults just ate
Limusaurus lived about plants. No one knows what
160 million years ago and the tooth fairy put under a
walked on two legs. Limusaurus’s pillow, though.
Paleontologists studied
fossils from 19
Limusaurus
specimens of
The news
different ages.
is complete. Go
Babies were about to page 45 to see
a foot (30 cm) long if you spotted
from nose to tail. the false story.
Adults were about 5
feet (1.5 m) long. And
although babies and
9READY, SET,
ECLIPS
An observer’s guide to the August 2017 eclipse
10T
he armies battled beneath the hot sun.
Neither side seemed to be winning. It was
May 28, 585 BCE, the sixth year of war
between the Lydians and the Medes in
by Meg Thacher what is now Turkey. Suddenly, the light
SE!
grew thin and the air turned cold. A hole
appeared in the sky where the sun should
be, surrounded by a halo of light. Surely
this was a sign from the gods that they
should make peace.
A total eclipse of the sun, as those ancient armies
witnessed, could be frightening if you didn’t know it was
coming. That fear could even stop a war! Nowadays, we
know what causes eclipses. We can predict when and
where they’ll happen, down to the minute and mile. Instead
of frightening people, an eclipse can bring millions of us
together in a wondrous moment of awe.
What Causes an Eclipse?
Earth orbits the sun, and the moon orbits Earth. The moon
passing between the sun and Earth causes a solar eclipse.
Although the moon is 400 times smaller than the sun, it’s
400 times closer to Earth. That means they look the same
size when viewed from Earth.
During an eclipse, the moon casts a fuzzy shadow on the
Earth. The center part of the shadow is called the umbra;
people in the umbra see a total eclipse. For these viewers,
darkness falls as the moon entirely covers up the sun. The
gray, fuzzy part of the shadow is the penumbra; people here
see a partial eclipse. The farther you are from the center, the
less sun is covered up.
The moon takes about 27 days to orbit the Earth, but we
don’t have eclipses every month. That’s because the moon’s
orbit is tilted five degrees to our orbit around the sun. So
the moon is often too high or too low when it’s between
us and the sun. An eclipse happens only when the sun, the
moon, and Earth line up perfectly.
The moon’s orbit is an ellipse (oval), so sometimes
it’s closer to us and looks bigger, and sometimes it’s
farther away and looks smaller. If it appears too small to
completely cover the sun, we’ll see an annular eclipse,
where a bright ring of light is visible around the moon.
When the moon is on the opposite side of Earth from the
sun, we may experience a lunar eclipse. If the sun, Earth,
Mark your and the moon line up right, the full moon will cross into the
calendar for the Earth’s shadow. Because Earth’s shadow is bigger than the
Great American moon’s, we see lunar eclipses more often than solar ones.
Eclipse: Where and When to See the Eclipse
August 21, On the morning of August 21, 2017, a total solar eclipse will
start in the middle of the Pacific Ocean. It will hit land in
2017 Oregon, run diagonally through the United States to South
Carolina, and end in the Atlantic Ocean. Everyone else in
11What You’ll See
James Lowenthal is a vice president
of the American Astronomical
Society and a member of its Solar
Eclipse Task Force. He’s seen three
total, two annular, and many partial
eclipses. He says a total solar eclipse
is “a deeply moving sight.”
When the eclipse starts, put on
your eclipse glasses or use a safe
viewer. Careful observers will see
the moon take a little bite out of
the sun. If you’re not using a safe
eclipse viewer to look at the sun, you
won’t notice anything. But about 30
minutes into the eclipse, the light
will look . . . thinner. “We know how
bright it should be with the sun in a
clear blue sky,” says Lowenthal, “but
it’s somehow not bright enough.”
Because the sun is a crescent, it
North America and people in Hawaii and parts of South
America will be able to see a partial eclipse. A total solar A solar eclipse happens
when the sun, the moon,
eclipse hasn’t occurred the United States since 1979! and Earth line up like this.
The map above has horizontal yellow lines that tell you
how much of the sun will be eclipsed. The path of totality
(where you can see a total eclipse) is a wide yellow stripe.
The vertical green lines tell you what time you’ll see the
eclipse. For example, Boston will see a partial eclipse at
2:47 p.m. (14:47 on a 24-hour clock). Denver will have a
slightly darker partial eclipse at 11:47 a.m.
The next total solar eclipse in North America will be
on April 8, 2024; its path will run south to north. The 2017
and 2024 eclipse paths cross in Carbondale, Illinois. Those
lucky folks have a chance to see a total eclipse twice!
LOCAL ECLIPSE TIMES FOR MAJOR CITIES ON THE PATH OF TOTALITY
Eclipse Totality Maximum Totality Eclipse
Location Begins Begins Eclipse Ends Ends Duration
Salem, OR 9:05 AM 10:17 AM 10:18 AM 10:19 AM 11:37 AM 1m 57.6s
Casper, WY 10:22 AM 11:42 AM 11:43 AM 11:45 AM 1:09 PM 2m 28.3s
Lincoln, NE 11:37 AM 1:02 PM 1:03 PM 1:03 PM 2:29 PM 1m 25.3s
Jefferson City, MO 11:46 AM 1:13 PM 1:14 PM 1:15 PM 2:41 PM 2m 29.9s
Nashville, TN 11:58 PM 1:27 PM 1:28 PM 1:29 PM 2:54 PM 1m 58.2s
Greenville, SC 1:09 PM 2:38 PM 2:39 PM 2:40 PM 4:02 PM 2m 12.7s
Columbia, SC 1:13 PM 2:41 PM 2:43 PM 2:44 PM 4:06 PM 2m 29.7s
Charleston, SC 1:16 PM 2:46 PM 2:47 PM 2:47 PM 4:09 PM 1m 42.5s
12MY ECLIPSE STORY
by Jay Pasachoff
appears a little skinnier than usual, and shadows will look
sharper. And if you look under the trees, you’ll notice that I saw my first solar eclipse as a college freshman 57
the circles of light you usually see are now crescent shaped! years ago, from an airplane over the Atlantic just off
As the moon covers more of the sun, it will get darker the Boston coastline. Since then, I’ve seen 64 additional
out, and the temperature will drop. Animals will start solar eclipses. My interest in studying the sun at
getting ready for night. Birds will roost. A few minutes eclipses has taken me all over the world. I’ve seen 33
before totality, you may see shadow bands—wiggly stripes total eclipses so far, from the Arctic, from an airplane
overflying the Antarctic, from Africa, North America,
of light and dark that move quickly across the ground.
South America, Asia, and Europe. And from some mid-
These may occur when the light of the thin crescent sun ocean islands and ships. But I have never seen a total
comes through the Earth’s wiggly atmosphere. Then, eclipse from the United States mainland.
look west. You’ll see darkness, “as if it’s night over there To be outdoors as the universe around you darkens,
and it’s daytime where you are,” says Lowenthal. This is with the light turning eerie and shadows sharpening in
the shadow of the moon rushing toward you at over a way that makes you uneasy, is the most remarkable
2,000 miles (3,200 km) per hour. experience I have ever witnessed. So I am very much
When you can’t see the sun at all through your eclipse looking forward to this all-American eclipse that crosses
glasses, it’s safe to take them off. You may see Baily’s Beads, the continental U.S. from West Coast to East Coast for
little specks of sunlight shining between the mountains on the first time since 1918.
the moon. Then you’ll start to see the corona—the sun’s As an eclipse astronomer, I have enjoyed hospitality
from colleagues all over the world when viewing
outer atmosphere—around the moon and one final bead of
eclipses in their countries, so now it is our turn to
sun shining through. It’s known as the diamond ring effect. be hosts. And my children, who started seeing total
Because it’s only dark where you are, you’ll see something eclipses when they were two years old and a few
like a 360-degree sunset. months old, respectively, will now be joined by their
During totality, the corona appears like a bright crown children. We will also be joined by my professional team
around the black disk of the moon. The corona is about as of astronomers and students from countries around the
bright as the full moon. It’s shaped by the sun’s magnetic world, astronomers who are coming with their families
fields, and it’s different every eclipse. We see its inner region for the spectacle, and others.
only with a special telescope or during a total eclipse. I looked at maps showing statistics of cloudiness
As your eyes adjust to the darkness, you’ll see red on August 21sts from the last couple of decades and
prominences at the moon’s edge. You’ll see stars and decided to observe the eclipse from Salem, Oregon. But
statistics are not reality, and we can but hope for clear
weather for our group and for all the people across the
country and the continent, especially for those in the
path of totality as it passes through parts of 14 states.
My colleagues and I have devoted a lot of time
to spreading the word about how exciting it is to be
outdoors to experience totality firsthand, and we hope
you get a chance. If all you can see is a partial eclipse
where you are, perhaps you can try again in 2024, when
the zone of totality will travel from Mexico up through
the eastern United States and into eastern Canada.
Happy observing!
Jay Pasachoff is Field Memorial Professor of Astronomy at
Williams College in Massachusetts.
13It is not safe to view the eclipse through things like
sunglasses, potato chip bags, DVDs, or smoked glass. Even if
they look dark, they could be letting in ultraviolet light. You
can’t see it, but UV light will harm your eyes.
If you look through a telescope, binoculars, or a camera,
it’s even more important to have a filter on the main lens.
You can place a pair of eclipse glasses on your phone’s
camera. But, Lowenthal says, “you don’t want to fiddle with
equipment too much—enjoy the experience of totality.”
PINHOLE PROJECTOR
The simplest pinhole projector is made of two white paper
plates. Poke a tiny round hole in one of them using a
thumbtack. Standing with your back to the sun, hold the
In this edited, layered photo, the sun’s corona surrounds the plate with the hole at about shoulder height. Place the
dark circle of the moon. Pasted in the center of the dark circle intact plate in its shadow. The pinhole will project an image
is a filtered image of the sun that shows magnetic activity. of the sun on the bottom plate. (Don’t look through the
Around the outside, in red false color, are outer coronal
streamers as viewed from a special spacecraft camera. pinhole at the sun!) You can make a fancier pinhole camera
using a shoebox.
Look for natural pinholes (like trees) during the eclipse.
planets in the sky. And all too soon, you’ll see the diamond Or try lacing your fingers together, and see how many
ring again, this time with the single bright bead on the other eclipse images you can make on a white surface. Try
side of the sun. You may see shadow bands again, and the punching out your name or a pattern in the paper
moon’s shadow running off to the east. plate projector.
The eclipsed sun will suddenly be bright again. You’ll You can also draw the eclipse, journal it, and share it
need to put your eclipse glasses back on to protect your on social media.
eyes (cover up cameras and telescopes with correct filters Here’s hoping you get to see the eclipse of 2017. Where
too!). The birds will wake up and start singing as if it’s will you be for the eclipse of 2024?
morning. The light will get stronger. When the last little bite
of the moon disappears, everything will be back to normal. Meg Thacher is a 52-year-old astronomer who has never seen a total
If you’re not on the path of totality, you may still see eclipse live. She will be in the path of totality on August 21.
the partially eclipsed sun and crescent shadows under the
trees. You may observe a temperature drop, weird animal
behavior, and planets in the daytime sky. But if you are able
to get to the path of totality, you should—there’s nothing
else like it!
How to Observe Safely
You should never look directly at the sun, even if the moon
is blocking most of it. Your eye’s lens focuses light on your
retina (the part that detects light). And because the retina
doesn’t have any pain receptors, you can hurt your eyes
without even knowing it. There are two simple ways to see
an eclipse without risking damage.
SOLAR-VIEWING GLASSES
These are not sunglasses! They’re usually made of cardboard,
with special filters that block out 99.99 percent of the sun’s
light. Make sure your solar-viewing glasses (or eclipse
glasses) meet the ISO 12312-2 standard. The three companies
that make approved glasses are Thousand Oaks Optical,
Rainbow Symphony, and American Paper Optics. Before
using them, hold them up to an indoor light to look for
scratches and holes. If you find any, throw those glasses out!
14text and art by Caanan Grall
INFOGRAPHIC BY MEG THACHER JOHN GORDON-SWOGGER
SUNSPOTS are
magnetic storms.
SURFA
They look dark
because they’re
cooler than the
photosphere. They
can be 10 times the CE
E
size of Earth.
ER
PH CONVE
CT
OS
IO
OT
PH
RAD
N
IAT
ZO
NE
IVE
ZON
CO
E
R
E
FILAMENTS are
squiggles of cool gas
in the chromosphere.
16ANATOMY
OF A STAR ÝÝ
Most stars are so far away that
it takes years for their light to
get to us. But sunlight is only 8
minutes away (93 million miles,
or 150 million kilometers). We
can learn about other stars by
studying the sun close up.
CORE
27 million0 F (15 million0 C)
➜The sun is powered by nuclear
fusion. In short: hydrogen atoms
smash together to make helium
atoms. Each helium atom has a
little less mass than the hydrogen
atoms it formed from. That
mass difference turns into a
A CORONAL MASS EJECTION lot of energy.
(CME) happens when gas
[INSIDE THE SUN]
blasts off the sun’s surface RADIATIVE ZONE
at 186 miles (300 km) per 13 million0 F (7 million0 C)
second. If a CME hits the to 4 million0 F (2 million0 C)
Earth’s atmosphere, we see the ➜ In the radiative zone, photons
beautiful aurora, also called (tiny particles of light) carry
northern and southern lights. energy outward from the core.
Each photon takes about a million
years to get to the convection
zone!
CONVECTION ZONE
3.6 million0 F (2 million0 C)
RE
to 9,8000 F (5,4000 C)
➜Here, hot bubbles of gas rise
HE
to the sun’s surface, cool off,
SP
and sink back to the bottom of
the zone to heat up again.
MO
NA
RO
RO
PHOTOSPHERE
10,0000 F (5,5000 C)
CH
CO
to 72000 F (40000 C)
➜This is the part of the sun we see
every day. This illustration shows
the sun’s surface as seen through
a filter, making the chromosphere
visible. The photosphere is
underneath the chromosphere.
CHROMOSPHERE
[SUN’S ATMOSPHERE]
10,0000 F (5,5000 C)
to 35,0000 F (20,0000 C)
➜The chromosphere is visible
with a special filter that lets in
only red light. During a solar
eclipse, it appears as a faint
red ring around the moon.
CORONA
1.8 million0 F
PROMINENCES are filaments seen (1 million0 C) or more
from the side. During an eclipse, ➜Unless you have a fancy X-ray
they look like red loops sticking out telescope, the corona is only
from behind the edge of the moon. visible during a solar eclipse. It is
a million times fainter than the
photosphere. The corona is made
of very energetic electrons and
ions streaming out into space.
17Science@Work
by Peg Lopata
MARLA GEHA
ASTRONOMER
Marla Geha works at Yale University in New
Haven, Connecticut. In addition to teaching
astronomy, Geha studies the formation,
evolution, and destruction of dwarf galaxies.
Dwarf galaxies are the most abundant
type of galaxy in the universe, but they’re
difficult to detect because they’re not very
bright and are—as the name suggests—
small in size. Maybe you wouldn’t think
someone needs to use the world’s largest
telescopes to study the universe’s smallestt
galaxies, but that’s exactly what she does.
18WHAT GOT YOU WHAT PROBLEMS ARE YOU WORKING ON
INTERESTED IN RIGHT NOW?
ASTRONOMY? The main question I am working on right now is measuring the
I liked math and physics mass or weight of the faintest or least luminous known galaxies
when I was in school, but I in the universe. Many of these orbit around our Milky Way—the
also wanted to travel. Since I galaxy Earth is in. These “ultra-faint” galaxies are several million
am an astronomer, I get to do times fainter than the Milky Way itself. Turns out, despite being
both. Many of the telescopes I called “dwarf galaxies,” they are not small—but very massive, even
use to do research are located though they have so few stars.
atop mountains in truly
beautiful and remote places, SO THESE “DWARF GALAXIES” MAY NOT BE SO SMALL
such as Chile and Hawaii. AFTER ALL?!
Right. We think this “extra” mass is due to dark matter. Dark matter
SOUNDS EXOTIC is made up of particles that have mass, or weight, but don’t produce
AND FUN. WHAT any light. These galaxies have a larger ratio of dark matter to stars—
OTHER INVENTIONS, more so than any other galaxies. In other words, these ultra-faint
BESIDES TELESCOPES, galaxies have more dark matter given the number of stars they have
HAVE HELPED than any other galaxies in the known universe. They are way more
ASTRONOMERS LIKE massive than we would expect based on their light. So studying
YOU MAKE ADVANCES them may help us to better understand what exactly dark matter is.
IN THIS FIELD? That could be important because there’s evidence that much of our
By far the most important universe is made of dark matter.
invention in my field, besides
telescopes, has been camera CAN WE SEE ANY DWARF GALAXIES WITH THE
phones. We astronomers use NAKED EYE?
the same technology that is Yes, there are two you can see from South America, Australia, or
in personal camera phones to Africa. They are called the Magellanic Clouds. These two dwarf
take pictures of planets, stars, galaxies orbit around our Milky Way. But they are only visible in the
and galaxies. Taking digital Southern Hemisphere.
images of the sky has com-
pletely changed the questions WHAT’S THE MOST AMAZING THING YOU’VE
we ask about the universe. LEARNED ABOUT A DWARF GALAXY?
The stars in many dwarf galaxies are very old and were likely formed
WOW! SO I CAN USE when our universe was very young. So these galaxies give us a window
MY PHONE TO TAKE A into what the universe might have been like 13 billion years ago.
PHOTO OF A PLANET
OR A STAR? YOUR STUDIES SOUND REALLY OUTTA THIS WORLD!
Well, our camera phones are WHAT KINDS OF JOBS MAY BE AVAILABLE FOR
much larger than the ones on SOMEONE INTERESTED IN ASTRONOMY?
phones many people own. A Astronomy can open doors to so many different types
typical camera phone is about of careers. Studying astronomy really means
12 megapixels. Our camera studying physics, math, statistics, and
phones are 550 megapixels. computer science. All of these topics
are in huge demand now and will
ALL THOSE MEGAPIXELS be even more important in the
MEAN YOU CAN TAKE future. My students have gotten
PHOTOS OF THINGS jobs in a wide variety of places,
FAR AWAY AND THE even working on developing
IMAGES ARE PRETTY video games.
CLEAR, RIGHT? SOUNDS
FASCINATING. WHAT DO Peg Lopata is a freelance writer
YOU LOVE MOST ABOUT living in Vermont. Her favorite
YOUR JOB? galaxy is the Milky Way because
I get to choose what that’s her home and her first
problems to work on. choice for a candy bar.
Keck Observatory, Hawaii 19by Nick D’Alto
E c l i p s
I S a w THE LEA
D IN N AS A’S E
the
CLIP SE BALL
O O N PROJECT.
TAKE
Building a New Kind of ÒSpaceshipÓ
TS
STUDEN
To do it, student teams must send high-altitude balloons
to a region of the atmosphere called “near space.” These
C
ould anything be more amazing than seeing a eclipse watching-devices will travel nearly 100,000 feet,
total solar eclipse? How about seeing that eclipse or about 19 miles (30 km) above Earth. Each balloon
from space? resembles a kind used in weather forecasting, Des Jardins
Peering down miles above the Earth (higher than says. Filled with helium, it measures 6 feet (1.8 m) in
the clouds), you would see not only the moon crossing the diameter on the ground. But the balloon will expand to
face of the sun, but also the shadow of the moon racing across over 30 feet (9 m) across when it reaches near space
oceans and continents, silhouetted against the blackness of because the lower air pressure up there allows the helium
space and the curving horizon of Earth. But you’d need to be inside to expand. “Then, past about 100,000 feet,” she says,
an astronaut to see something like that, wouldn’t you? “the balloon will burst.”
Not anymore. On August 21, 2017, hundreds of young Beneath each balloon, several instrument payloads
people will see it too. And they’ll share it with the world in will dangle from a long flying line. (“Payload” describes
near real time. Welcome to the amazing Eclipse Ballooning something a vehicle carries for its purpose or mission.)
Project, in which teams of students across the United States “Two of these will watch the eclipse: a digital camera to
will launch devices high into the air to observe the Great capture still images and a video camera, which records in
American Eclipse in a whole new way. They will capture HD,” says Des Jardins. Both are controlled by Raspberry
photos and videos as the eclipse sweeps the nation and Pi, low-cost, credit card–sized computers you might use
then send them back to Earth. in school science projects. Both are also equipped with
“It’s really a golden opportunity,” says Angela Des
Jardins, director of the Montana Space Grant Consortium
and head of the project. “And it’s all about emerging
technologies coming together. Like miniature radio,
The still image
technology from drones, and the ability to stream live payload uses
video.” The Montana program is part of NASA’s National a Raspberry Pi
Space Grant College and Fellowship Program. Combining and Pi Camera to
take, store and
these various forms of tech will accomplish something transmit images
historic. “We’ve seen a few eclipses from the International via a modem.
Space Station,” Des Jardins notes, “and from single high-
altitude balloons. But continuous, real-time coverage of
an eclipse from off Earth has never been done before.”
20de
h-altitu
and tested hig at Montana
uilt ops
Teams b during worksh
s
balloon iversity.
State Un
S p ac e!
from
se — To “catch” the data its balloon transmits, each team
will operate its own ground-based tracking station.
These tiny mission controls include a directional antenna
equipped with motors that keep it pointed towards the
balloon’s signal. Then each team will automatically upload
the pictures and videos they receive to the project website.
Preparing the Flight Crews
How will students accomplish something that would
have been impossible the last time an eclipse crossed the
United States?
Technology, enthusiasm, and hard work. Already,
more than 50 high school, college, and university teams
This container is have trained for months with their science advisors.
ready to house just They’ve learned how to assemble the equipment. Much
about any payload.
of it is both advanced and super lightweight. Teams have
constructed the capsules from Styrofoam! Then they’ve
wireless modems (like the ones your smartphone uses), to learned how to get into the air. “It’s not always easy,” Des
send the pictures they take down to the ground. Jardins confesses, “especially since half our teams have
But wait—how do you point the cameras at the eclipse never launched balloons before.” In test launch videos,
from many miles up? In effect, you don’t. “Some commands they shout, “Hold it!” and “Go this way more!” In May
can be sent up to the payloads, through their modems,” Des and July 2016, teams from 30 states completed five-day
Jardins explains. “But the cameras will still spin around in
the wind.” To deal with this, some teams are experimenting
with fins to keep the cameras pointing straight. “Others
are just filming constantly,” she adds, “As wind whips the
cameras around, the eclipse should come in and out of
view.” (Boy, could this make viewers dizzy!)
“We also need to know where the balloon is at all times,”
Des Jardins says, “especially once it leaves visual range.” So
a third module uses GPS to track the balloon’s location—
with a little help. It uses a modem that can contact a
network of satellites in orbit around Earth’s poles.
There's a first time for
everything—including
balloon launching.
21an Line.
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workshops at Montana State University to build and test Four instrument
their systems. Team members have mastered skills from payloads dangle
soldering and programming to web design. All the while from a long flying
line beneath each
they’ve been gearing up for the flight of a lifetime. balloon.
Liftoff!
Each team has established a flat, open launch site along
the eclipse’s path of totality. Teams from outside that zone
What a view!
will travel to their launch points. On eclipse day, balloons
will rise from schoolyards, parks, airports, and golf courses
nationwide. “Each team must get their balloon high
enough, and far enough, to meet the eclipse as it arrives,”
Des Jardins notes. “So timing is key.” She explains that the
balloons rise at about a thousand feet (305 m) per minute.
That means it would take about 90 minutes to reach 90,000
feet (27,400 m). Balloons may also drift up to 100 miles (161
km) from their launching points, depending on the winds
they encounter. That’s why some teams will set up their
tracking stations at a distance from the launch site. The
wind may blow the balloons to them.
Cut the Rope
There’s one more payload instrument on board. “That’s the
cut-down module,” Des Jardins explains. When a balloon’s
mission is complete, or if it strays into restricted
22Ever wondered where Earth's atmosphere
ends and space begins? Take a look at the
Karman Line at left.
shadow as it crosses our planet. Des Jardins
says, “It’s looking toward Earth where the
magic will happen.” The eclipse’s shadow,
called its penumbra, is about 70 miles (113
km) wide. Des Jardins estimates that from
the balloons’ heights, a radius of about 100
miles (161 km) will be visible.
This viewing area is ideal. “You’ll be able
to see where the land is sunlit,” Des Jardins
says, “and where it isn’t—where the eclipse
is happening. And you’ll see the edges of the
atmosphere, glowing. That will be amazingly
cool.” Teams will see the eclipse cross lands
and landmarks nationwide.
In effect, the Eclipse Ballooning Project
aims to take Earth’s first eclipse selfies!
Illustrators have created images of the Earth
from above during eclipses, and NASA has
filmed it from space, but we’ve never seen
it in real time. Here’s a chance to see an
eclipse from a whole new perspective.
You Can See It Too
Teams will stream images to the NASA
website as data arrives. “As it’s happening,”
Des Jardins notes, “you’ll be able to visit
the site, and see and compare live feeds
from different teams’ balloons along the
route.” How will the eclipse look as it sweeps
toward the Rocky Mountains? (There will be
air space, a signal can tell its modem to cut the line. (A a team nearby.) Or as it crosses the Great Plains? (There will
tiny cutting wheel does the job.) As the payloads fall from be teams there too.) To find out, visit eclipse2017.nasa.gov
the balloon, a parachute will open and carry them safely on eclipse day, and see for yourself!
back to Earth. If the balloon bursts before the mission is
complete, the parachute will open automatically. Having no high-altitude cameras handy, engineer Nick D’Alto will
watch the eclipse with a pinhole camera from the ground.
Earth’s First Eclipse Selfie
These balloons’ cameras aren’t trying to capture images of
the sun during the eclipse. (The cameras aren’t telescopes.)
Instead, they’ll help us see the eclipse’s
23MINI-MYTH JESSE TISE 24
25
MINI-MYTH 26
by Mara Johnson-Groh
There
She
Blows!
I
magine a frozen, icy world where
huge geysers shoot water vapor up
higher than the tallest mountains on
Earth. This bizarre landscape exists
on Europa, one of Jupiter’s moons.
Europa is one of the few places in
our solar system harboring oceans. The
moon’s oceans likely contain twice as
much water as Earth’s, but they are
buried under many layers of ice. This
makes them really hard to study, though
many scientists want to take a closer
look. Oceans are some of the most
promising places in our solar system to
look for alien life.
Using the Hubble Space Telescope,
astronomers found evidence that giant
geysers on Europa shoot up plumes of
water vapor. The plumes reach 125 miles
(about 200 km) above the surface—
more than 20 times the height of Mount
Everest. These eruptions allow scientists
to see the ocean water from afar. That’s
a lot easier than going all the way to
Europa to drill through the thick ice.
On an average day, Europa is a chilly
-260°F (-162°C). So how does this space
snowball have a liquid ocean and giant
vapor fountains? One theory holds
that as Europa travels around Jupiter,
the giant planet’s gravity squishes and
squeezes the moon, heating up its
insides. This keeps the ocean liquid, even
though the moon’s surface temperature
is so frigid. The heating may also explain
the geysers, though astronomers don’t
yet know their exact cause.
If you want to head to Europa to
check out the moon’s natural wonders,
don’t get too close: much of the water
vapor rains back down on the surface
as tiny ice pellets!
27by Rachel Zimmerman Brachman So Long, Saturn CASSINI’S MARVELOUS MISSION IS COMING TO AN END. 28
I
f you’re under 20, NASA’s Cassini spacecraft has
been in space your whole life. If you’re under 13,
Cassini has been orbiting Saturn your whole life. This
robotic spacecraft is about a billion miles (1.6 billion
km) from Earth, learning about Saturn’s rings and
moons, watching its storms, and measuring its moons.
Scientists have lots of questions about Saturn. Why
does Saturn have massive storms that last for months
or years? How old are its rings, and how were they
formed? Could any of its moons support life? NASA’s
Cassini spacecraft is helping scientists answer these
questions, and many more.
A SPACECRAFT WITH A SPECIAL BLANKET
As big as a school bus, Cassini is the largest interplanetary
spacecraft that NASA has ever built.
Cassini ’s shiny gold-colored foil blanket protects the
spacecraft from tiny bits of rock that could damage its
sensitive scientific instruments. The blanket also keeps
the spacecraft warm in the cold vacuum of space. Some of
the layers of insulation are made from materials similar to
those in bulletproof vests.
The large, white, dish-shaped communications antenna
at the top of the spacecraft points toward Earth. Cassini
uses the antenna to transmit its pictures and data as radio
signals. The signals travel all the way to the Earth-based
Deep Space Network—a group of enormous radio antennas
located in Spain, Australia, and California. This network
also sends commands to Cassini. Traveling at the speed
of light, the signals sent to and from Cassini can take
an hour and a half to traverse the vast distance between
the planets.
Cassini has 12 different science instruments on board,
including cameras, radar, a magnetic field detector, and
instruments to figure out which chemical elements are
present in Saturn and its moons.
Technology has improved a lot in the past 20 years.
Cassini ’s one-megapixel camera may not seem very
impressive now, but back in the 1990s, when the spacecraft
was built, this camera was cutting-edge! Back then, most
people didn’t have cell phones or digital cameras. Now
almost every cell phone comes with a built-in digital camera.
The latest iPhone camera has 12 megapixels.
A probe called Huygens, built by the European Space
Agency, piggybacked on the voyage from Earth to Saturn.
It parachuted through Titan’s atmosphere to take pictures
of the moon’s surface. It found that Titan’s surface has
mountains and dry rivers and lakes, and its rocks are
weathered and rounded.
MISSION: EXTENDED
Cassini was built at NASA’s Jet Propulsion Laboratory in
Pasadena, California. It was launched from Cape Canaveral,
Florida, on October 15, 1997. After a seven-year trip through
space, it began orbiting Saturn on June 30, 2004.
29Learon Morebout the
ut more a
d e
You can fin craft, and see all of th
i sp a ce f S atu rn
Cassin ken o
ssini has ta
This mission to Saturn has lasted nine images Ca rings and moons, at to
and its t
If you wan
years longer than originally planned.
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Cassini has captured
valuable images of
Saturn’s many moons,
including this one,
called Dione.
team of scientists on the Cassini mission meets to
discuss the most exciting science discoveries, as well as
important engineering issues.
A NASA illustration shows Cassini’s flight path during the final
two phases of its mission. The 20 Ring-Grazing Orbits are gray; the CLOSE UP ON RINGS AND MOONS
22 Grand Finale Orbits are blue. The final partial orbit is orange. Saturn’s beautiful rings are made of ice, dust, and rock.
Although they stretch as far across as the distance from
Cassini was supposed to spend four years orbiting the Earth to the moon, each ring is only a few hundred feet
Saturn, from 2004 to 2008. But the mission was so thick. That means they’re extremely thin! Small “shepherd
successful that it was granted a two-year extension moons” orbit within the rings. Saturn’s larger moons orbit
(2008–2010) and then a seven-year extension (2010–2017). much farther away from the planet. Like the rings, the
The spacecraft slowly changes its orbital path around moons are made of ice and rock.
Saturn to get a good view of the rings or the moons, since it Cassini took the first close-up images of many of
can’t do both at once. Science planners work with planetary Saturn’s 62 moons. It helped scientists discover several
scientists to decide what the craft should study over the of the moons.
next few months, and navigators figure out how to get Saturn’s largest moon, Titan, is the second-largest
Cassini safely into position to collect the pictures and data moon in the solar system, even larger than the
the scientists need. Every few months, the international planet Mercury! Titan is the only moon with a dense
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