Earth Science Enterprise
- Why is the ozone hole a problem?
- The ozone layer is a thin band in Earths upper atmosphere.
It blocks out the Sun's harmful ultraviolet (UV) rays. If it gets too
thin, the harmful UV rays can damage crops, wild animals, and our skin.
- What causes the ozone hole?
- We earthlings have damaged the ozone layer with chemicals (called
chlorofluorocarbons or CFCs) that are used in refrigerators and air
conditioners. This has been proved by a long series of measurements from
space and on the ground. In fact, the Nobel Prize in Chemistry has been
awarded to three atmospheric scientists for having discovered and
explained this link.
- Is the ozone hole getting bigger?
- It isn't really a "hole", but a large decrease in the total
amount of ozone overhead. It is truly a large decrease over Antarctica
at certain times of the year, but there are significant general
reductions in ozone elsewhere, including the Northern Hemisphere. The
"hole" and the general reductions elsewhere are not getting better yet.
We expect that things will improve, starting early in the next century.
- What is El Niño?
- The El Niño effect is the interaction of the wind and the sea
and the warming of sea water. During a year when there is no El
Niño, trade winds move surface water west across the Pacific
Ocean and bring cold water from deep below to the top. The cold water
from the ocean floor has food in it that the fish eat, such as plankton
and algae. When El Niño happens, the strong, steady, easterly
winds die off and cold water does not rise any more from the deep. Then
the water at the surface warms up and fish food is not replaced. So, the
fish food stays at the bottom of the ocean where they cant get to
it. Since the fish dont have food to eat, they swim to other
oceans where they can find food. But the most important impact of El
Niño is the effect on the weather.
- What does the name El Niño mean?
- Every three to five years during the months of December and
January, fish in the waters off the coasts Peru and Ecuador vanish like
magic. This causes much damage to the areas fishing industry. A
long time ago fishermen who fished in these waters called this big fish
disappearance "El Niño," because it happened near the celebration
of the birth of Jesus, the Christ Child. El Niño is Spanish for
referring to the Christ Child.
El Niño from March to November 1997
(the white streak across the middle of the picture)
- Does El Niño affect the rest of the world?
- It sure does. The weakening of trade winds that causes the
waters temperature in the Pacific Ocean to rise knocks many of
Earths climates out of whack! Warm water in the Pacific ocean
moves the jet stream (fast winds, 8-10 miles high) so that storms that
used to hit Alaska now reach California. Scientists believe El
Niño caused flooding in Texas during the winter of 1991-1992 and
very warm temperatures in the southeast part of the U.S. that same
winter. It may have caused droughts which made some bird species become
- How is NASA and Earth Science helping to study El Niño?
- Scientists at
NASA use satellites to study Earth. These satellites send back pictures
of Earths continents, oceans, clouds, and the atmosphere.
Scientists use these pictures to study changes in the sea temperatures
and clouds in the atmosphere. This helps them detect clues that tell if
El Niño may be brewing. Scientists are working hard to be able to
predict El Niño a year before it happens so people in countries
prone to El Niño floods or droughts will know before the disaster
strikes and be ready for it.
- What is polar ice and how does it affect the Earth?
- Polar ice is ice that covers the Earths polar regions. It
makes up 10% of the Earths surface. It is made of different kinds
of ice: sea ice, glaciers and ice sheets. Sea ice forms when sea water
freezes. Ice sheets and glaciers form when snow builds up faster than it
can melt. Polar ice affects the Earth in many ways. It can change the
water level of the oceans, the temperature and climate of an entire
region, and alter the exchange of heat between the ocean and the air
- Are sea levels rising?
- Yes, oceans are rising on the average. Rising by as much as 15 to
20 cm (about 6 to 8 inches) in the last 100 years. The seas actually
appear to be rising fast because the land is actually sinking in some
places and rising in others. On the average, though, the global sea
level is rising, sometimes at a much faster rate.
We do not know yet how much of the rising sea level is caused by
melting of glaciers, that add water to the oceans, or by expansion of
the existing ocean water due to slow warming. Rising ocean levels would
make hurricanes and other storms more dangerous. More than half the U.S.
population lives within 50 miles of a coastline. Some entire nations -
like Bangladesh and the Netherlands - are at or near sea level.
- How does sea ice act like a mirror and how does lots of sea ice
cause temperatures to get cooler?
- Sea ice reflects the suns rays. When the sun shines down
onto the ice, it reflects the sunlight back into space away from Earth.
The more sea ice there is, the more solar energy gets reflected back
into space and the less heat stays on Earth. This causes the climate to
- Where are the world's two largest ice sheets and why is NASA
- The two largest ice sheets are in Greenland and Antarctica.
Together, they contain 75% of the world's fresh water. If all this ice
melted back into the ocean it would raise sea level by over 75 meters.
This would change Earths surface in a big way: whole continents
could even be submerged underwater! This is why Earth scientists use
satellites to measure the ice levels on Greenland and Antarctica to see
if they are growing or shrinking.
- What would happen if there were less ice on the Earth?
- The climate would get warmer. Since there would be less ice to
reflect the sunlight back into space, more of it would be absorbed by
Earth making it warm up.
- What causes global warming?
- The heat radiated from the Earth is absorbed by carbon dioxide,
water vapor, and other gases in our air. Thus, the Earth keeps more of
the heat that would otherwise have been lost to space.
The amount of carbon dioxide in the air has increased a lot in the
past hundred years. And recently we have seen increases in the other
greenhouse gases. Many scientists believe this will lead to a gradual
warming of the Earth. Others believe that different factors cancel this
warming effect. Studying these processes is difficult, because they are
- What is the temperature in space?
- It depends on whether you are asking what is the temperature "of"
space, or the temperature of things that are "in" space. Strictly
speaking, space really doesnt have any temperature since it is
mostly empty. Only things that can be found in space such as atoms and
ions, have any temperature. Near Earth and the Moon, if you are in
direct sunlight, you could heat up to 250 degrees F (121 degrees C).
This is hotter than boiling water at 212 degrees F. In the shade, it can
cool to around -250 degrees F (-156 degrees C). This is why astronauts
must wear thermal space suits.
- Is there any chance for a school to run a science experiment on
- Yes, tell your teacher about NASA's Get Away Special (GAS) program. It
allows science and engineering experiments to fly aboard the Space
Shuttle. It costs money, but a big company could sponsor you or your
class. So, if you or your school are interested, contact:
Shuttle Small Payloads Project
Customer Support Office
Greenbelt MD 20771
- When the NASA astronaut put a flag on the Moon, did he claim it
as property of the United States like Columbus claimed America for Spain
when he landed here?
- No, because the United Nations Treaty on Outer Space signed in
1967 prevents any nation from owning planets, stars, or any objects
found in space. The NASA astronaut placed the flag on the Moon to let
the world know that "America went in peace for all Mankind."
This is the actual law:
ARTICLE I: ..." Outer space, including the moon and other celestial bodies,
shall be free for exploration and use by all States without discrimination of any
kind, on a basis of equality and in accordance with international law, and there
shall be free access to all areas of celestial bodies. There shall be freedom of
scientific investigation in outer space, including the moon and other celestial
bodies, and States shall facilitate and encourage international cooperation in
ARTICLE II: " Outer space, including the moon and other celestial bodies,
is not subject to national appropriation by claim of sovereignty, by means of
use or occupation, or by any other means."
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