©
ho
to, Chris Das
ch
JULY 2008: Is there life on
other planets? Early this year,
scientists got one step closer
to solving that mystery.
They pointed the Hubble
Space Telescope at a newly
discovered planet outside
our solar system. The Jupitersized planet is called HD
189733b. As the planet
passed in front of its star,
it blocked some of the star’s
light. Scientists could “read”
this light to tell what
chemicals exist on the planet.
The scientists got a big
surprise. The planet contained
a chemical called methane!
What’s so
big about
methane?
Methane
is an organic
compound.
Organic compounds contain
carbon, and they often come
from living things. Organic
compounds are the building
blocks of life. This is the first
time an organic compound
has been found outside our
solar system.
© Corbis, Royalty-free, Steve Nagy
er
www.sciencea-z.com
© iStockphoto, Taily
4
Swamp Gas
from Outer Space!
© iStockphoto,
JC Photography
kp
© Learning A–Z, Inc. All rights reserved.
a division of Learning A-Z
By Kate Follett
© iS
toc
Silicon-based life?
Organic compounds all contain carbon.
People say living things on Earth are “carbon-based.”
But some people wonder if life on other planets might
be made up of totally different chemicals. For instance,
the element silicon can
act a lot like carbon. Most
scientists doubt there could
be life made of silicon.
But it makes you wonder
how different life on other
planets might be!
presented by
Photos.com
A terrarium is a container
that has everything living
things need to survive. It
has light, water, soil, plants,
and animals. Building a
colony on another planet
might be like building a terrarium. The colony must have
everything that living things need to grow.
Imagine that part of your classroom is a new planet.
Build a pretend colony on the planet by creating an
“Outer Space Terrarium.” Include everything that living
things—including you—need to survive on this new
planet. Use signs or labels to show each thing you will
bring to the planet.
© Clipart.com
© iStockphoto, Snowshill
Outer Space Terrarium
See Swamp Gas From Outer Space! on page 2
1
2
© Clipart.com
Phoenix Lander
This summer, scientists found water
ice on Mars. They already knew
that there was ice at the planet’s
north pole. But they thought there
might also be ice elsewhere, just under the soil. To test
their theory, they sent a robot called the Mars Phoenix
Lander. It dug into the soil and found water ice! The robot
will do tests to find out whether the ice has ever been
liquid. If it has, organisms may have survived on Mars.
3
© NASA.gov
© Learning A–Z, Inc. All rights reserved.
What would living things
look like on an
alien world?
How would
they survive?
© Photo Researchers, Inc., Eye of Science
Anaerobic comes from the Greek
words an (without), aero (air),
and bios (life). It means “without
the air of life” or “without oxygen.”
The word aerobic means “with
oxygen.” So when you
do aerobic exercises,
you huff and puff!
Write About This!
© Clipart.com
Does this mean there are
swamps, garbage dumps,
and stinky animals on HD
189733b? Probably not. HD
189733b is very close to its
star, so it is probably far too
hot for life. And methane
can come from non-living
things such as volcanoes. But
scientists were excited to find
the building blocks of life far
outside our solar system.
© iStockphoto, Clee Villasor
Methane is common on
Earth. It is found in natural
gas, which forms when dead
plant and animal matter gets
squeezed inside Earth’s crust.
It is also found in swamps,
landfills, and other places
where things decompose, or
rot. Special living things called
anaerobic microorganisms
(tiny living things that don’t
use oxygen) break down
plant and animal matter
and give off methane. Some
anaerobic microorganisms
even live inside animals. They
help break down an animal’s
food, releasing methane gas.
Methane traps heat in Earth’s
atmosphere. What’s one big source
of methane? Cow burps! Humans
raise billions of cows for meat and
milk, and their digestive gases pile up
in the atmosphere. Some scientists are
looking for ways to make cows less
gassy in order to fight climate change.
© iStockphoto, Jan Brons
Continued from page 1
© Clipart.com
Swamp Gas From Outer Space!
www.sciencea-z.com