A Lumpy Planet
So you yearn to explore strange worlds in distant galaxies, going where no Earthling has gone before? And you're feeling very depressed that for technical reasons your trip might be delayed a few centuries…or maybe forever? Well, how about visiting the world in this photo? Is it weird enough for you?
Gravity map Courtesy NASA
Surprise! It's Earth. But not as we normally see it. This image shows Earth as it is seen by instruments that are sensitive to gravity instead of light. Gravity isn't the same all over the planet. The mappers turned places where you'd feel slightly heavier into high spots and ones where you'd feel slightly lighter into lows. One of the lows is in India (the blue and pink area to the right of center). You'd weigh about a pound less if you went to India (if you weighed about 100 pounds normally).
Scientists think the gravity map reveals what's going on deep inside Earth, in the part called the mantle, where the rock is still solid but hot enough that it flows slowly. That low off of India may be linked to an ancient collision—the collision of India with Eurasia, which pushed up those wrinkles on the surface of Earth we call the Himalayas.
It just goes to show: There's no place like (or as weird as) home!
- gravity: Pulling forces between objects.
- Why might it be important for scientists to study how the pull of gravity varies around the planet? What might this knowledge be used to do? Write a short paragraph exploring the benefits of scientists studying the Earth's gravity.
[anno: Answers will vary.]