how many star on the space?

That's a fantastic question! The simple answer is: We don't know the exact number, but we can make a very good estimate.

When we ask "how many stars in space," we're really asking about the observable universe—the part we can see. The number is almost incomprehensibly large.

Here’s how astronomers break it down.

The Short Answer

A common estimate from astronomers is that there are roughly 200 billion trillion stars in the observable universe.

Let's write that out:
200,000,000,000,000,000,000,000

That's a 2 followed by 23 zeros. Another way to say it is 10²³ stars.

How We Get to That Number

Astronomers can't count every single star, so they use a method involving multiplication.

1. Estimate stars in a typical galaxy: Scientists study galaxies and estimate that an average-sized galaxy contains about 100 million to over 1 trillion stars. A common, conservative average used is 100 billion stars per galaxy.
2. Estimate the number of galaxies: When the Hubble Space Telescope took deep-field images, it showed that a tiny, seemingly empty patch of sky is filled with thousands of galaxies. By extrapolating this to the entire sky, astronomers estimate there are between 100 billion and 200 billion galaxies in the observable universe.
3. Do the math:Low estimate: 100 billion stars/galaxy × 100 billion galaxies = 10,000,000,000,000,000,000,000 (10 sextillion)High estimate: 100 billion stars/galaxy × 200 billion galaxies = 20,000,000,000,000,000,000,000 (20 sextillion)The often-cited average: 200 billion stars/galaxy × 200 billion galaxies = 40,000,000,000,000,000,000,000 (40 sextillion)

The figure of 200 billion trillion (or 10²³) is a popular, rounded-off estimate that falls right in this range.

Important Things to Consider

• The Universe is Mostly Empty: Despite this huge number, the universe is mostly empty space. The average density of stars is incredibly low.
• The Observable Universe: This number only applies to the stars we could potentially see. The entire universe might be much, much larger—possibly infinite—so the total number of stars could be infinite as well.
• It's an Estimate: These numbers are based on our current best technology and models. As telescopes like the James Webb Space Telescope discover more and older galaxies, these estimates are constantly being refined.

To give you some perspective:

• There are more stars in the universe than grains of sand on every beach on Earth.
• The number of stars is about 10,000 times larger than the number of words ever spoken by every human who has ever lived.

So, while we can't say "there are exactly X stars," we can confidently say the number is truly astronomical

把以上译成中文

这是一个很棒的问题！简单的答案是：我们不知道确切的数字，但我们可以做出一个非常好的估算。

当我们问“太空中有多少颗星星”时，我们实际上是在问可观测的宇宙——也就是我们能看到的那一部分。这个数字大得几乎无法理解。

以下是天文学家的分解方式。

简短的回答

天文学家普遍估计，在可观测的宇宙中，大约有 2000亿万亿颗恒星。

让我们把这个数字写出来：
200,000,000,000,000,000,000,000

也就是2后面跟着23个零。另一种说法是 10²³ 颗恒星。

这个数字是如何得出的

天文学家不可能数清每一颗恒星，所以他们用一种涉及乘法的方法来估算。

1. 估算一个典型星系中的恒星数量： 科学家研究星系并估计，一个中等大小的星系包含大约1亿到超过1万亿颗恒星。一个常用的、保守的平均值是每个星系有 1000亿颗 恒星。
2. 估算宇宙中星系的总数： 当哈勃太空望远镜拍摄深场图像时，它显示出一小片看似空无一物的天空中充满了数千个星系。将这一结果推算到整个天空，天文学家估计在可观测宇宙中，大约有 1000亿到2000亿个 星系。
3. 进行计算：低估值： 1000亿颗恒星/星系 × 1000亿个星系 = 10,000,000,000,000,000,000,000 (1千亿亿亿，即10的22次方)高估值： 1000亿颗恒星/星系 × 2000亿个星系 = 20,000,000,000,000,000,000,000 (2千亿亿亿，即2×10的22次方)一个常被引用的平均值： 2000亿颗恒星/星系 × 2000亿个星系 = 40,000,000,000,000,000,000,000 (4千亿亿亿，即4×10的22次方)

2000亿万亿（或10的23次方）这个数字是一个流行的、四舍五入后的估算值，正好落在这个范围内。

需要考虑的重要事项

• 宇宙基本上是空的： 尽管恒星数量巨大，但宇宙大部分是空旷的空间。恒星的平- 可观测的宇宙： 这个数字仅适用于我们有可能看到的恒星。整个宇宙可能要大得多——甚至可能是无限的——所以恒星的总数也可能是无限的。
• 这是一个估算： 这些数字基于我们目前最好的技术和模型。随着像詹姆斯·韦伯太空望远镜这样的设备发现更多、更古老的星系，这些估算也在不断地被修正。

给你一些直观的对比：

• 宇宙中的恒星数量比地球上所有海滩上的沙粒总数还要多。
• 恒星的数量大约是古往今来所有人类说过的所有单词总数的1万倍。

所以，虽然我们不能说“确切有X颗恒星”，但我们可以有把握地说，这个数字确实是天文数字。