Why is the ozone hole a problem?

The ozone layer is a thin band in Earth’s 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 can’t get to it. Since the fish don’t 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 area’s 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 water’s temperature in the Pacific Ocean to rise knocks many of Earth’s 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 extinct.

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 Earth’s 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 Earth’s polar regions. It makes up 10% of the Earth’s 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 above.

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 sun’s 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 become colder.

Where are the world's two largest ice sheets and why is NASA studying them?

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 Earth’s 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 very complicated.

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 doesn’t 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 the Shuttle?

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 such investigation."

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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