Astronomy & Space Exploration

11101 said:
Important to remember these are all computer modified images. JWST is infrared only unlike Hubble.
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It's a bit more actually; here is the relevant bit from Wikipedia:
JWST is designed primarily for near-infrared astronomy, but can also see orange and red visible light, as well as the mid-infrared region, depending on the instrument. It can detect objects up to 100 times fainter than Hubble can, and objects much earlier in the history of the universe, back to redshift z≈20 (about 180 million years cosmic time after the Big Bang). For comparison, the earliest stars are thought to have formed between z≈30 and z≈20 (100–180 million years cosmic time),[12] and the first galaxies may have formed around redshift z≈15 (about 270 million years cosmic time). Hubble is unable to see further back than very early reionization at about z≈11.1 (galaxy GN-z11, 400 million years cosmic time).

The design emphasizes the near to mid-infrared for several reasons:
  • high-redshift (very early and distant) objects have their visible emissions shifted into the infrared, and therefore their light can only be observed today via infrared astronomy;
  • infrared light passes more easily through dust clouds than visible light
  • colder objects such as debris disks and planets emit most strongly in the infrared;
  • these infrared bands are difficult to study from the ground or by existing space telescopes such as Hubble.
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Spectacular. Blown away by the pictures.
Imagine dropping acid in space.
 
Just to mention that there is a programme starting 20:00 UK time on BBC2 about the JWST.
 
Probably won’t find this interesting but a guy on Twitter saw an Einstein Cross.

Just below the south-west arm of that mega bright star which dominates the photo (a star in our own galaxy which is in the way!) there’s a galaxy with four dots around it.

This is a star/object with a galaxy in front of it but due to the gravity of the galaxy, the light has bent perfectly around it so we see the same star/object at four separate areas around the galaxy.

Mind blowing.
 
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Camy89 said:
Probably won’t find this interesting but a guy on Twitter saw an Einstein Cross.

Just below the south-west arm of that mega bright star which dominates the photo (a star in our own galaxy which is in the way!) there’s a galaxy with four dots around it.

This is a star/object with a galaxy in front of it but due to the gravity of the galaxy, the light has bent perfectly around it so we see the same star/object at four separate areas around the galaxy.

Mind blowing.
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Oh yeah, gravitational lensing is super cool. Usually the object being "lensed" is a galaxy too, and sometimes they're really far away.
 
Ignorant question: if better or more advanced telescopes can allow us to look further into the past, is it possible in theory to create a telescope that would actually allow us to see the big bang?
 
maniak said:
Ignorant question: if better or more advanced telescopes can allow us to look further into the past, is it possible in theory to create a telescope that would actually allow us to see the big bang?
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As far as my limited knowledge goes, I would say no.

You wouldn’t be able to see an explosion or anything. For many millions of years after the Big Bang there were no stars/galaxies and just matter/gas/elements floating around which we wouldn’t be able to see.

I don’t think it would be able to be seen with our eyes, I think maybe only on other wavelengths.

Happy to be corrected though.
 
Camy89 said:
As far as my limited knowledge goes, I would say no.

You wouldn’t be able to see an explosion or anything. For many millions of years after the Big Bang there were no stars/galaxies and just matter/gas/elements floating around which we wouldn’t be able to see.

I don’t think it would be able to be seen with our eyes, I think maybe only on other wavelengths.

Happy to be corrected though.
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We would be able to "see" stuff that isn't galaxies, theoretically, but we'll never be able to see further back than when the universe stopped being opaque. That's 3-400k years after the Big Bang.
 
maniak said:
Ignorant question: if better or more advanced telescopes can allow us to look further into the past, is it possible in theory to create a telescope that would actually allow us to see the big bang?
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Planck_satellite_cmb.jpg


This is the earliest the universe has been “pictured”, its the Cosmic Microwave Background. Its the light from when the universe became stable enough to produce atoms and thus photons which by this time has been red-shifted to the microwave range. Estimated to be from ~400k years after the big bang. Theoretically, it should not be possible to picture the big bang before that.
 
golden_blunder said:
My little brain can’t fathom us being able to see “back in time” when looking through this telescope
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The universe is vast and the speed of light is finite, therefore the light we are seeing was produced X amount of years ago. The likelihood is the galaxies that produced that light are no longer there; for example if the Sun were to disappear we wouldn't know about it for 8 minutes as that's the amount of time it takes the light from the Sun to reach Earth.
 
That'sHernandez said:
The universe is vast and the speed of light is finite, therefore the light we are seeing was produced X amount of years ago. The likelihood is the galaxies that produced that light are no longer there; for example if the Sun were to disappear we wouldn't know about it for 8 minutes as that's the amount of time it takes the light from the Sun to reach Earth.
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What about if I get a telescope and look through it, will I be able to see my neighbour stripping off for a shower in her bathroom like she used to when i was 16?
 
That'sHernandez said:
The universe is vast and the speed of light is finite, therefore the light we are seeing was produced X amount of years ago. The likelihood is the galaxies that produced that light are no longer there; for example if the Sun were to disappear we wouldn't know about it for 8 minutes as that's the amount of time it takes the light from the Sun to reach Earth.
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The galaxies are definitely still there. Well, they moved, but they didn't explode or anything.
 
maniak said:
Ignorant question: if better or more advanced telescopes can allow us to look further into the past, is it possible in theory to create a telescope that would actually allow us to see the big bang?
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That's the Theory.
 
nimic said:
We would be able to "see" stuff that isn't galaxies, theoretically, but we'll never be able to see further back than when the universe stopped being opaque. That's 3-400k years after the Big Bang.
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That is my understanding as well.
That point is strangely referred to as Recombination. Even though there was no previous Combination.
The combination is the point at which the plasma had cooled sufficiently to allow the to protons and electrons to combine into hydrogen resulting in the opaque clearing.

Before that, our universe was just a hot opaque plasma with no atoms.
 
Buster15 said:
That is my understanding as well.
That point is strangely referred to as Recombination. Even though there was no previous Combination.
The combination is the point at which the plasma had cooled sufficiently to allow the to protons and electrons to combine into hydrogen resulting in the opaque clearing.

Before that, our universe was just a hot opaque plasma with no atoms.
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The weak and strong nuclear forces came into play as you know
 
golden_blunder said:
My little brain can’t fathom us being able to see “back in time” when looking through this telescope
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We always look back in time as it takes time for the light to reach our eyes. A telescope is just a light receiver in a similar sense. So the further an object is away the further back in time were seeing it. If an alien civilisation looking at earth right now was 70m light years away they'd be able to see the dinosaurs.
 
maniak said:
Ignorant question: if better or more advanced telescopes can allow us to look further into the past, is it possible in theory to create a telescope that would actually allow us to see the big bang?
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As I understand we can not see as far back as the Big bang with our "eyes". We do however see it as background radiation.
 
maniak said:
Ignorant question: if better or more advanced telescopes can allow us to look further into the past, is it possible in theory to create a telescope that would actually allow us to see the big bang?
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Dumbstar said:
That's the Theory.
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Before 370,000 years after the big bang, the universe was not a place where photos (light particles) could move freely. This is because there were free electrons which cause something called Thomson Scattering.

Once the universe cooled sufficiently, electrons combined with protons to form neutral hydrogren (the misnamed recombination) and then photos decoupled from those hydrogen atoms.

At this point the universe had few enough free electrons to allow photons to pass and that's the (ref shifted version of the) CMB we see today

Note - I have no idea about Thomson Scattering
 
Frosty said:
I don't think that would be possible?

Between 240,000 and 300,000 years after the Big Bang was the first time that photons could rest for a second, attached as electrons to atoms. It was at this point that the universe went from being totally opaque, to transparent.
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That's interesting. I thought photons were unchanging, because they literally travel at the speed of the light.
nimic said:
We could theoretically make a telescope the size of the solar system. It would be in many, many parts, obviously. Though I think that would be more for getting really good looks at "closer" things, than necessarily looking as far/far back as possible.
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What do you mean? How could you make a telescope the size of the solar system? The size of the telescope is limited by the mass available on earth.
 
VanDeBank said:
What do you mean? How could you make a telescope the size of the solar system? The size of the telescope is limited by the mass available on earth.
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The Event Horizon Telescope is the 'size' of the Earth by combining data from a number of telescopes across the world and their respective fields of vision: https://eventhorizontelescope.org/about

You could make a telescope array that is positioned around the solar system and get the effect of a solar system sized telescope. I think.
 
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