The Heliosphere 日球层

转自 The Heliosphere - NASA

This is an artist's concept of our Heliosphere as it travels through our galaxy with the major features labeled.

Termination Shock:
Blowing outward billions of kilometers from the Sun is the solar wind, a thin stream of electrically charged gas. This wind travels at an average speed ranging from 300 to 700 kilometers per second (700,000 – 1,500,000 miles per hour) until it reaches the termination shock. At this point, the speed of the solar wind drops abruptly as it begins to feel the effects of interstellar wind.

Heliosphere:
The solar wind, emanating from the Sun, creates a bubble that extends far past the orbits of the planets. This bubble is the heliosphere, shaped like a long wind sock as it moves with the Sun through interstellar space.

Heliosheath:
The heliosheath is the outer region of the heliosphere, just beyond the termination shock, the point where the solar wind slows abruptly, becoming denser and hotter. The solar wind piles up as it presses outward against the approaching wind in interstellar space.

Heliopause:
The boundary between solar wind and interstellar wind is the heliopause, where the pressure of the two winds are in balance. This balance in pressure causes the solar wind to turn back and flow down the tail of the heliosphere.

Bow shock:
As the heliosphere plows through interstellar space, a bow shock forms, similar to what forms as a ship plowing through the ocean.

Also present in this illustration are the two Voyager spacecraft with their approximate paths out of the Heliosphere. Voyager I was deflected northward above the plane of the planets’ orbits when it swung by Saturn in 1980. Voyager II was deflected downward by Neptune and is heading southward below the plane of the planets.

激波边界 Termination Shock

从太阳向外吹出数十亿公里的是太阳风，一种稀薄的带电气体流。这种风以每秒300到700公里（每小时70万到150万英里）的平均速度传播，直到到达终点震波。在这一点上，太阳风的速度突然下降，因为它开始感受到星际风的影响。

日球层 Heliosphere

从太阳发出的太阳风产生了一个气泡，远远超出了行星的轨道。这个气泡就是日球层，形状像一只长长的风袜，随着太阳在星际空间中移动。

日鞘层 Heliosheath

日鞘层是日球层的外部区域，就在终止激波之外，在这里太阳风突然减速，变得更密集、更热。当太阳风向外挤压星际空间中接近的风时，它就会堆积起来。

日球层顶 Heliopause

太阳风和星际风之间的边界是日球层顶，在这里两种风的压力是平衡的。这种压力的平衡导致太阳风转向并沿着日球层的尾部向下流动。

弓形激波 Bow Shork

当日球层在星际空间中穿行时，就会形成弓形激波，就像船只在海洋中穿行一样。

在这幅插图中，还有两艘旅行者号宇宙飞船，以及它们离开日光层的大致路径。旅行者1号在1980年掠过土星时，在行星轨道平面上向北偏转。旅行者2号受海王星的影响向下偏转，现在正朝着行星平面下方的方向南行。

The Heliosphere - NASA

Credit: NASA/Goddard/Walt Feimer Link to unlabeled version