Understanding Our Solar System's Movement

Every second, you move about two hundred and thirty

kilometers through the galaxy,

and you never feel it.

We picture the solar system like a clock, planets circling a

sun that stays put. But the sun does not

stay put.

It is racing around the center of the Milky Way, carrying

every planet with it. So after one year,

Earth is back at the same point in its orbit,

but the orbit itself has moved. You are more than seven

billion kilometers from where you started.

One lap of the galaxy takes about two hundred and thirty million

years.

The last time the sun was here, the first dinosaurs were only just

appearing. And we do not travel unprotected.

The sun's wind streams outward at around a million miles an

hour, inflating a vast bubble around the

entire solar system, the heliosphere.

It deflects roughly three-quarters of the galactic cosmic rays that would

otherwise reach us. Its edge is so far out that

Voyager One, launched in nineteen seventy-seven, needed

thirty-five years to get there. And here is the surprise:

Most diagrams draw a shockwave out front, like a

boat cutting through water.

There isn't one. We drift through the interstellar gas at

just

twenty-three kilometers per second.

Too slow for a shock,

only a gentle bow wave.

So the next time you look up, remember,

you are riding inside a bubble, sweeping through the

galaxy, and you have never once felt it move.