安裝中文字典英文字典辭典工具!
安裝中文字典英文字典辭典工具!
|
- What Is Gravity? | NASA Space Place – NASA Science for Kids
What Is Gravity? Gravity is the force by which a planet or other body draws objects toward its center The force of gravity keeps all of the planets in orbit around the sun What else does gravity do? Why do you land on the ground when you jump up instead of floating off into space? Why do things fall down when you throw them or drop
- Why Are Planets Round? | NASA Space Place – NASA Science for Kids
Why Are Planets Round? The Short Answer: A planet is round because of gravity A planet's gravity pulls equally from all sides Gravity pulls from the center to the edges like the spokes of a bicycle wheel This makes the overall shape of a planet a sphere, which is a three-dimensional circle
- What Is a Gravitational Wave? - NASA Space Place
A gravitational wave is an invisible (yet incredibly fast) ripple in space We’ve known about gravitational waves for a long time More than 100 years ago, a great scientist named Albert Einstein came up with many ideas about gravity and space Albert Einstein, official 1921 Nobel Prize in Physics photograph Einstein predicted that something special happens when two bodies—such as planets
- How Do We Weigh Planets? - NASA Space Place
However, scientists do have ways to figure out how much a planet weighs They can calculate how hard the planet pulls on other things The heavier the planet, the stronger it tugs on nearby objects—like moons or visiting spacecraft That tug is what we call gravitational pull What does gravity have to do with weight?
- What Is a Barycenter? | NASA Space Place – NASA Science for Kids
We say that planets orbit stars, but that’s not the whole truth Planets and stars actually orbit around their common center of mass This common center of mass is called the barycenter Barycenters also help astronomers search for planets beyond our solar system! What is a center of mass? Every object has a center of mass It is the exact center of all the material an object is made of An
- Videos | NASA Space Place – NASA Science for Kids
How Do We Launch Things Into Space? You need a rocket with enough fuel to escape Earth’s gravity! What Is a Nebula? What Is a Solar Eclipse? Learn more about what happens when the moon passes between Earth and the sun! explore Searching for Other Planets Like Ours Exoplanets are far away and hard to see How do we look for them
- Why Do We Send Robots To Space? - NASA Space Place
Why Do We Send Robots To Space? The Curiosity rover takes a self-portrait on a Martian sand dune Credit: NASA JPL-Caltech MSSS We can send robots to explore space without having to worry so much about their safety Of course, we want these carefully built robots to last
|
|
|