Why are Radio Telescopes less detailed?

  • Context: Stargazing 
  • Thread starter Thread starter Vorde
  • Start date Start date
  • Tags Tags
    Radio Telescopes
Click For Summary

Discussion Overview

The discussion centers around the differences in detail and resolution between images produced by radio telescopes and those produced by telescopes observing other parts of the electromagnetic spectrum. It explores the reasons behind these differences, including diffraction limits and the nature of the observed waves.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants note that radio telescopes have lower resolution due to diffraction limits, which are influenced by the longer wavelengths of radio waves compared to other electromagnetic waves.
  • It is mentioned that radio waves often originate from more diffuse sources, contributing to the lower detail in images.
  • One participant explains that Very Long Baseline Interferometry (VLBI) can enhance resolution by effectively creating a telescope the size of the Earth, allowing for more detailed images than those captured in the visible spectrum.
  • Another participant questions why VLBI is effective for radio waves but not for visible light, suggesting it relates to the ability to track wave peaks and synchronize measurements with atomic clocks.
  • There is a claim that the construction of radio telescope 'lenses' can be less precise, allowing for larger sizes compared to those needed for visible light telescopes.

Areas of Agreement / Disagreement

Participants express differing views on the effectiveness of VLBI for radio versus visible light, with some agreeing on the principles involved while others seek clarification on the underlying reasons.

Contextual Notes

Participants discuss the limitations of resolution due to wavelength and the nature of the waves, but do not resolve the complexities of why VLBI works differently for radio and visible light.

Vorde
Messages
786
Reaction score
0
In my experience pictures from radio antennae are far less accurate than pictures from other areas of the EMR spectrum, why is this?
 
Astronomy news on Phys.org
Vorde said:
In my experience pictures from radio antennae are far less accurate than pictures from other areas of the EMR spectrum, why is this?

For single telescopes the issue is diffraction limits. The minimum resolution that you can see is on the order of (wavelength) / (telescope size), and since radio telescopes have long wavelengths, you get less resolution.

The other issue is that radio waves often come from objects that are more diffuse.

Now things are very different for VLBI. With VLBI you use the rotation of the Earth and computers to create an artificial telescope that can be the size of the earth. In that situation, you can get pictures that are much more detailed than you have in visible.
 
twofish-quant said:
Now things are very different for VLBI. With VLBI you use the rotation of the Earth and computers to create an artificial telescope that can be the size of the earth. In that situation, you can get pictures that are much more detailed than you have in visible.
Why does the principle behind VBLI work for radio but not for visible?

I'm thinking it has something to do with the "I"...
 
twofish is correct, it has to do with wavelength. A radio telescope 'lens' is need only be corrected to within a few millimeters. That is why they can be made so large.
 
DaveC426913 said:
Why does the principle behind VBLI work for radio but not for visible?

Because with radio waves you can see the actual shape of the "wave". You can track exactly when the peak of the wave hits the Earth which is going to be different for different parts of the earth. Once you synchronize these measurements with an atomic clock, you can work back and electronically reconstruct the wave as it hits the earth.

For light, you can't record phase information, so you have to physically combine light rays. This means that you can't build an artificial telescope the size of the earth.
 

Similar threads

Undergrad How big a lunar radio telescope to detect Earth-like signals?
  • · Replies 19 ·
Replies
19
Views
3K
Undergrad Does it make sense to build new radio telescopes?
  • · Replies 46 ·
2
Replies
46
Views
3K
Stargazing Has a Deep Field Picture of the Sky Been Captured with a Radio Telescope?
  • · Replies 5 ·
Replies
5
Views
2K
High School Feasibility of Sending a Radio Signal Detectable from a Neighboring Star
  • · Replies 5 ·
Replies
5
Views
2K
Graduate Project Progress Report and possible Radio Astronomy Technique?
  • · Replies 9 ·
Replies
9
Views
3K
Undergrad Could fast radio bursts be alien radar signals?
  • · Replies 9 ·
Replies
9
Views
1K
Stargazing How is noise removed in radio telescopes?
  • · Replies 28 ·
Replies
28
Views
7K
High School Lunar Crater Radio Telescope (LCRT)
  • · Replies 1 ·
Replies
1
Views
2K
Stargazing Does a Radio Telescope Have Aberration and How Does it Affect Its Performance?
  • · Replies 9 ·
Replies
9
Views
3K
Graduate Resolving power of a radio telescope array: Quantum or classical?
  • · Replies 7 ·
Replies
7
Views
3K