| Africa |
Africa is one of the seven largest areas of land on the earth. These areas of land are called continents. Africa is the second largest continent on our planet. Only Asia is bigger than Africa. Africa is made up of more than fifty different countries, and people speak many different languages in these countries. Some of the languages are Swahili, Hausa, and Arabic. |
| alien |
a living being from another planet; extraterrestrial. There is no evidence that aliens exist, but many people believe there is life on other planets. [2/5 definitions] |
| Asia |
Asia is one of the seven largest areas of land on the earth. These areas of land are called continents. Asia is the largest of all the seven continents on our planet. Many different languages are spoken in Asia. Some of them are Chinese, Japanese, Hindi, Bengali, Farsi, and Arabic. |
| asteroid |
a small, rocky, planet-like body that circles the sun and is mostly found between the orbits of Jupiter and Mars. The size of an asteroid can vary from very tiny to six hundred miles across. |
| Atlantic Ocean |
The Atlantic Ocean is one of the five oceans on our planet. An ocean is a large body of salt water that covers a very large part of the earth. It is much bigger than a sea or lake. If you want to travel from America to Africa or Europe, you have to cross the Atlantic Ocean. |
| atmosphere |
The planet Earth is surrounded by gases. These gases all together are called Earth's atmosphere. As our planet travels through space and around the sun, its atmosphere stays with it. Other planets can have an atmosphere too, but Earth's atmosphere has just the right mixture of gases for humans to live. Our atmosphere lets us breathe and also protects us from the strong energy of the sun. [1/2 definitions] |
| biosphere |
When people talk about the biosphere, they are sometimes talking about all the living things that live in the air, water, or land around the planet Earth. They are talking about both the living things and the places where it is possible for them to live. [1/2 definitions] |
| carbon |
Carbon is one of the chemical elements found on Earth, and it is a very common element on this planet. It is also found all over the universe. Carbon atoms often combine with atoms of other elements, such as oxygen and hydrogen. Diamonds are an example of something made only of carbon atoms. [1/2 definitions] |
| climate change |
a major change in Earth's climate that is of current concern and which is associated with an increase in carbon dioxide and certain other gases in Earth's atmosphere. These gases contribute to the increasing temperature of the planet. [1/2 definitions] |
| core |
The center of a round, solid object is its core. The center part of our planet Earth is called the core. The core of the Earth is similar to the core of an apple because they are both at the very center. [1/4 definitions] |
| crater |
A crater is something on the surface of a moon or a planet. It is an area where the land has been pushed in and forms the shape of a huge bowl. Craters are usually made by very large rocks from space that land hard on the surface. Some craters on the moon are so large that we can see them from Earth. |
| crust |
the outer layer of Earth, another planet, or a moon. [1/5 definitions] |
| earth |
the outer layer of the planet; ground. [1/4 definitions] |
| earth science |
Earth science is the study of the planet Earth. Earth science is especially interested in what the planet is composed of, its weather, and how the planet developed and continues to change over time. Many different sciences, such as geology and meteorology--the study of weather--are part of earth science. |
| eclipse |
the blocking from view of the sun, a moon, or a planet by another heavenly body. In an eclipse of the sun, the sun is hidden from earth's view by the moon passing between the sun and the earth. [1/3 definitions] |
| environment |
When we talk about the environment, we often mean the natural things around all of us as we live on our planet Earth. The environment is made up of things like the air, the water, the plants, and the soil. We know now that we have to protect the environment. Things like pollution cause damage to it and cause harm to animals and humans. [1/3 definitions] |
| extraterrestrial |
existing or coming from a place outside planet Earth. |
| fantastic |
If something has a fantastic appearance, it looks very strange and unusual, maybe like something from another planet. [1/3 definitions] |
| farthest |
When something is farthest, it is the longest distance from something. The farthest planet is the most distant planet. [1/2 definitions] |
| galaxy |
a collection of billions of stars and other matter held together by gravity. Our planet Earth and the sun belong to the Milky Way galaxy. They are only tiny parts of this galaxy. |
| geology |
the land forms and rocks of a particular place on the earth or other planet. [1/2 definitions] |