**NeW**

How many things can you see in the night sky? A lot! On a clear night you
might see the Moon, some planets, and thousands of sparkling stars.
You can see even more with a telescope. You might see stars where before
you only saw dark space. You might see that many stars look larger than
ohters. You might see that some stars that look white are really red or blue.
With bigger and bigger telescopes you can see more and more objects in the
sky. And you can see those objects in more and more detail.
But scientists believe there are some things in the sky that we will never see.
We won't see them with the biggest telescope in the woreld, on the clearest
night of the year.
That's because tehy're invisible. They're the mysterious dead stars called
black holes.
You might find it hard to imagine that stars die. After all, our Sun is a star.
Year after year we see it up in the sky, burning brightly, giving us heat and
light. The Sun certainly doesn't seem to be getting old or weak. But stars do
burn out and die after billions of years.
As a star's gases burn, they give off light and heat. But when the gas runs out,
the star stops burning and begins to die.
As the star cools, the outer layers of the star pull in toward the center. The
star squashes into a smaller and smaller ball. If the star was very small, the
star ends up as a cold, dark ball called a black dwarf. If the star was very big,
it keeps squashing inward until it's packed together tighter than anything in
the universe.
Imagine if the Earth were crushed until it was the size of a tiny marble.
That's how tightly this dead star, a black hole, is packed. What pulls the star
in toward its center with souch power? It's the same force that pulls you down
when you jump- the force called gravity. A black hole is so tightly packed
that its gravity sucks in everything- even light. The light from a black hole
can never come back to your eyes. That's why you see nothing but blackness.
So the next time you stare up at the night sky, remember: there's more in the
sky than meets the eye! Scattered in the silent darkness are black holes- the
great mystery of space.

單字：

clear night - 沒雲層的夜晚
planets - 星球
sparkling - 一閃一閃
stars - 星體
telescope - 望遠鏡
dark space - 外太空
object - 物體
detail - 細微
invisible - 看不見
after all - 畢竟
burning - 燃燒
brightly - 亮
heat - 熱
certainly - 確定
burn out - 燃燒殆盡
give off - 供給
layers - 外表
pull - 拉
toward - 方向
squashes - 擠
universe - 全宇宙
crushed - 撞
tiny - 縮小
marble - 彈珠
force - 力量
gravity - 地心引力
sucks - 吸
blackness - 黑暗
stare up - 注視
scattered - 擴展
silent - 寧靜