And out of this information you get the radius, the velocity and the period, assuming that you are on Earth in the plane of the orbit of the stars.

除了这个，还能得到半径的大小，速度以及周期，假设你在地球上，和这些恒星环绕的，轨道同处一个平面。

youdao

Let's assume that the atmosphere goes up 1000 km above the Earth (when it is a sphere), and so is a sphere itself of radius 6400km+1000km=7400km.

让我们做个假定，如果大气层高过“地球”（如果确是球体的情况下）1000公里的话，那么地球本身的半径6400公里+1000公里=7400公里。

youdao

So again, if you know the radius, if you know how far you are away from the Earth, the period follows uniquely.

同样地如果知道半径，就能知道你离地球，多远，时间随之而来。

youdao

But there is a way to counter the increasing brightness of the Sun, the scientists believe - just increase the radius of the Earth's orbit!

BBC: Blue Marble Nasa

These eye-in-the-sky cell towers hover between 70, 000 and 100, 000-feet and provide coverage for a 200-mile radius on Earth- but the darn things only stay aloft for 24 to 48 hours before freefalling to the ground (or tree, or lake, or Grand Canyon).

ENGADGET: Cash-in on your geocaching skillz

Kepler 37b and c are about 30% and 74% as large as the Earth, and Kepler 37d is about twice Earth's radius.

BBC: Exoplanet Kepler 37b is tiniest yet - smaller than Mercury