<p>Radio telescopes cannot "see further" than optical telescopes but electromagnetic radiation in the range detected by radio telescopes may come from a further distance (i.e. from an earlier time) than detectable by optical telescopes and/or radio waves may penetrate things which are obscured at optical wavelengths.</p>

<p>The classic example of the first case is the cosmic microwave background (CMB) - actually the oldest detectable radiation in the universe (assuming our cosmology is even half-close to being right). This is the radiation that was emitted when the early expanding universe cooled just enough to allow hydgrogen atoms to form - the captured electrons gave off radiation and the universe's density was no longer great enough to ensure that radiation caused a balancing ionisation. That happened so long ago/so far away that it now looks like something very cold (about 3 degrees above absolute zero) and so is not detectable at visible wavelengths but is at microwave wavelengths.</p>

<p>The second case includes things like radiation from dust clouds in our galaxy - the dust blocks visual radiation but not radio waves.</p>

<p>But the premiss of your question is wrong in that it is not a question of dish size and certainly not magnification (the correct parallel with an optical telescope is also dish - or rather lens or mirror - size incidentally.)</p>

CC BY-SA 3.0
2017-06-13T14:34:53.563Z
2017-06-13T14:34:53.563Z
adrianmcmenamin
<p>I know that radio telescope can <em>'see'</em>* further than an optical telescope but I would like to know how much further? (let's say the optical has a magnification of 50x and the radio has a dish of 90m in diameter).<br>
*When I say see I mean how far into space image wise.</p>

CC BY-SA 3.0
2017-06-13T13:12:59.700Z
You've seriously misunderstood how telescopes work. One telescope cannot see further than another and their ability to see things has nothing to do with their magnification. The quality of a telescope which is important is its light collecting ability.
zephyr
<radio-telescope>
how much further can a radio telescope than an optical telescope
Some Random Awesome Guy
# how much further can a radio telescope than an optical telescope

(Asked by: username_0 on 2017-06-13)

I know that radio telescope can *'see'*\* further than an optical telescope but I would like to know how much further? (let's say the optical has a magnification of 50x and the radio has a dish of 90m in diameter).  
\*When I say see I mean how far into space image wise.

**Tags:** radio-telescope

> **Comments:**
> **username_1**: You've seriously misunderstood how telescopes work. One telescope cannot see further than another and their ability to see things has nothing to do with their magnification. The quality of a telescope which is important is its light collecting ability.  

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## 1 answers

### Answer by username_2 on 2017-06-13. Score: 3

Radio telescopes cannot "see further" than optical telescopes but electromagnetic radiation in the range detected by radio telescopes may come from a further distance (i.e. from an earlier time) than detectable by optical telescopes and/or radio waves may penetrate things which are obscured at optical wavelengths.

The classic example of the first case is the cosmic microwave background (CMB) - actually the oldest detectable radiation in the universe (assuming our cosmology is even half-close to being right). This is the radiation that was emitted when the early expanding universe cooled just enough to allow hydgrogen atoms to form - the captured electrons gave off radiation and the universe's density was no longer great enough to ensure that radiation caused a balancing ionisation. That happened so long ago/so far away that it now looks like something very cold (about 3 degrees above absolute zero) and so is not detectable at visible wavelengths but is at microwave wavelengths.

The second case includes things like radiation from dust clouds in our galaxy - the dust blocks visual radiation but not radio waves.

But the premiss of your question is wrong in that it is not a question of dish size and certainly not magnification (the correct parallel with an optical telescope is also dish - or rather lens or mirror - size incidentally.)


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