What is a lunar eclipse?

a lunar eclipse occurs when the earth casts a shadow on the moon.

a lunar eclipse occurs when the moon blocks out the view of the sun from earth.

a lunar eclipse occurs when the moon is closer to the sun in its orbit.

a lunar eclipse occurs when the earth is closest to the sun.

In 1915 the german geologist and meteorologist alfred wegener first proposed the theory of continental drift, which states that parts of the earth's crust slowly drift atop a liquid core. the fossil record supports and gives credibility to the theories of continental drift and plate tectonics.

Which of the following is not a challenge to instituting sound global environmental policies? a. most changes are inexpensive and easy to implement. b. elected leaders who support unpopular environmental issues often are not re-elected. c. economic considerations outweigh environmental ones in many societies. d. there is no way to enforce international environmental agreements.

Why is immigration so important today?