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Swamp Gas
from Outer Space!
big surprise. The
planet contained
one
of
the
building
blocks
of life—a chemical
called methane!
JULY 2008: Is there life on
other planets? Early this year,
astronomers found an exciting
clue to this mystery. The
scientists pointed the Hubble
Space Telescope at a recently
discovered planet 63 light
years from Earth. The planet
is called HD 189733b. As this
Jupiter-sized world passed in
front of its star, its atmosphere
blocked some of the star’s light.
Scientists could “read” this light
to tell which chemicals exist on
the planet. The scientists got a
What’s so big about methane?
Methane is an organic
compound, a chemical that
contains carbon and often
comes from living things.
Organic compounds make up
the bulk of life, including you
and me. This is the first time
an organic compound has
been found outside our solar
system.
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By Kate Follett
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ph
ck
a division of Learning A-Z
© iStockphoto, JC Photography
Scientists use special tricks to
spot extrasolar planets. As a
planet orbits, its gravity pulls
the star in little circles. Scientists
can spot this movement with
telescopes. Some planets pass
in front of their stars as they
orbit. This blocks some of the
star’s light, making it look
dimmer. These changes in
faraway stars are very tiny. But
we’re finding more extrasolar
planets every year!
What makes a
compound organic?
Organic compounds contain
er
h
carbon. This is why people say that living things
sc
on Earth are “carbon-based.” But maybe life
on other planets is made of totally different
stuff than life on Earth!
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to
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First, extrasolar planets are
extremely far away, so they
are hard to see even with
telescopes. Second, planets do
not give off their own light,
so they don’t show up against
the blackness of space. Third,
planets orbit, or move in a
circle, around stars. Stars give
off very bright light, which
makes it almost impossible
to see nearby objects. It’s like
trying to follow a golf ball in
front of the Sun, only trillions
of miles away!
oto, Chris D
a
t.com
pa r
Cli
All known extrasolar planets,
or planets outside our solar
system, were found in just the
last fifteen years. Why is finding
extrasolar planets so hard?
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Search for the
Invisible Planets
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4
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1
So does this mean there are
swamps, garbage dumps, and
stinky animals on HD 189733b?
Probably not. For one thing, the
planet is very close to its star,
making it way too hot for life
as we know it. Also, methane
can come from non-living
things, such as volcanoes. But
scientists hope they will find
methane and other organic
compounds on faraway planets
that are more like Earth. They
are excited to know that the
building blocks of life exist
outside our solar system.
© Learning A–Z, Inc. All rights reserved.
2
Anaerobic microbes
What would living things
look like on an
alien world?
How would
they survive?
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Phoenix Lander
This summer NASA sent a robot called
the Phoenix Lander to Mars to discover
whether liquid water ever flowed on
the planet’s surface. Previous satellites had already
revealed a large ice cap at Mars’s north pole and scientists
believed that there was ice just under the soil, elsewhere.
The Phoenix Lander arrived on Mars on May 25, 2008
after a nine-month journey, and began testing the soil.
It found water ice just beneath the surface! If this ice was
ever liquid, it’s possible that living organisms once thrived
on Mars. The Lander will keep testing to find out.
3
© NASA.gov
Anaerobic comes from the Greek
words an (without), aero (air), and
bios (life), meaning “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!
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way or another, most methane
on Earth today comes from
living or once-living things.
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Methane is very common on
Earth. It is found in natural
gas, which formed when
ancient plant and animal
matter got squeezed inside
Earth’s crust. Methane is also
found in swamps, landfills,
and other places where things
decompose, or rot. Special
organisms called anaerobic
microorganisms (or tiny
organisms that live without
oxygen) break down plant
and animal matter and give
off
methane.
Anaerobic
microorganisms even live
inside some animals, such as
cows. They help the animal
break down its food, and they
release methane gas. In one
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, Clee Villasor
Continued from page 1
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Swamp Gas From Outer Space!
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