# Space: Color and Resources

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• nivamani Rajbongshi
I'm an AI and not capable of answering this question since it is not related to the original conversation about space.Also what feul we use in the space(i mean outside earth), i mean to change the direction of the satellite or any space craft. We usually see a gas is used to move them, what gas is it?There are different types of fuels used in spacecraft, including liquid hydrogen, liquid oxygen, and hydrazine. These fuels are used in rocket engines to provide the necessary thrust for a spacecraft to change its direction or speed.We consider time as the 4th dimension but when we speak about space time what is the dimension of the space??In the theory of general relativity, space and time are combined intof

#### nivamani Rajbongshi

When we see with open eyes or in visible range of wavelength of e.m. wave we see black space containing some star...but if we see the space in other range of wavelength of the e.m. wave what will we see?? Also why the space is black?? Which matel we find in space mostly? Can we extract those matel to use?

Also why the space is black?? Which matel we find in space mostly? Can we extract those matel to use?
The space between the stars is black because (on average) the first non-transparent stuff in the way of our line of sight is the primordial incandescent plasma that existed in the epoch of recombination before the universe became transparent to light. That was a long time ago. Due to the expansion of the universe, the light from that plasma has red shifted so much that it is now invisible. Instead, that "light" is now observed as the cosmic microwave background radiation.

It is much more convenient to find metal in mines rather than in hard vacuum.

nivamani Rajbongshi, russ_watters and berkeman
but if we see the space in other range of wavelength of the e.m. wave what will we see??

Mostly blackness until you get down into the microwave wavelengths. Once there you will see the cosmic microwave background radiation.

Also why the space is black??

Because you're mostly seeing empty space with no visible light coming from it. Hence, blackness.

Which matel we find in space mostly?

Hydrogen is overwhelmingly the dominant material in space, coming in at nearly 74% of the material in space by mass. This is followed by helium at almost 24% the amount by mass. The remaining 2% amount is where you find all the other elements.

Can we extract those matel to use?

Not yet. The interplanetary and interstellar medium is too sparse, and we don't yet have the ability to mine asteroids or other planets.

The space between the stars is black because (on average) the first non-transparent stuff in the way of our line of sight is the primordial incandescent plasma that existed in the epoch of recombination before the universe became transparent to light. That was a long time ago. Due to the expansion of the universe, the light from that plasma has red shifted so much that it is now invisible. Instead, that "light" is now observed as the cosmic microwave background radiation.

It is much more convenient to find metal in mines rather than in hard vacuum.
Why we assume that the light didn't reach to us so we see the space black mostly...also u r telling about some plasma, what is it?? Also u said universe is expanding then why we see the same star from a specific region in the sky?

A hydrogen balloon alway move upward. But at which layer of atmosphere it release from the balloon? Also what feul we use in the space(i mean outside earth), i mean to change the direction of the satellite or any space craft. We usually see a gas is used to move them, what gas is it? We consider time as the 4th dimension but when we speak about space time what is the dimension of the space??

Why we assume that the light didn't reach to us so we see the space black mostly

The only reason something looks black is because it emits or reflects little light, or if something blocks the light. So space is black because either little light is being emitted from most of space, or because there's something blocking the light from reaching us. But we can look out into space and see for billions of light years, so the light can't simply be blocked by something, otherwise we wouldn't be able to see distant regions of the universe. That must mean that there just isn't anything out there emitting or reflecting much light, and the latter is ruled out because, like I said, we can see for billions of light years without our view being obstructed or the light be significantly scattered by reflecting objects. That just leaves the idea that space is mostly empty.

also u r telling about some plasma, what is it??

https://en.wikipedia.org/wiki/Plasma_(physics)

Also u said universe is expanding then why we see the same star from a specific region in the sky?

Every single star you can see is located within our own galaxy, and galaxies do not expand. Instead, it is the distant between galaxies or galaxy clusters that are increasing over time. This is the expansion of the universe. Also note that space is enormous. Even though galaxies are moving at hundreds of thousands of kilometers per hour or faster you can't see a difference in their positions over timeframes of anything less than thousands or millions of years. Space is simply that vast.

A hydrogen balloon alway move upward. But at which layer of atmosphere it release from the balloon?

I'm sorry but I don't know what you're asking.

Also what feul we use in the space(i mean outside earth), i mean to change the direction of the satellite or any space craft. We usually see a gas is used to move them, what gas is it?

There are dozens of rocket fuels and oxidizers that have been used, each with its own advantages and drawbacks. Here's a list of liquid propellants that have been used: https://en.wikipedia.org/wiki/Liquid_rocket_propellant#Table

We consider time as the 4th dimension but when we speak about space time what is the dimension of the space??

Three of the dimensions are spatial dimensions and the final dimension is time. It doesn't matter how you number them. Space is called the 4th dimension simply because the three spatial dimension were labeled first in history.