Theoretical Resolution of Hubble

Click For Summary

Discussion Overview

The discussion centers around the capabilities of the Hubble Space Telescope, particularly in relation to imaging distant objects such as the moon landing sites and the sensitivity of the telescope in detecting faint light sources. Participants explore the implications of angular resolution and exposure time in capturing images of dim objects.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant claims that Hubble's angular resolution is insufficient to image the moon landing sites, questioning a statement made by a former director of Hubble regarding its ability to detect light from a firefly at that distance.
  • Another participant suggests that while Hubble can detect faint light sources due to its sensitivity, it may not resolve closely spaced objects as separate sources.
  • A further contribution emphasizes that Hubble can gather enough photons to detect dim objects by extending exposure times, noting that it can take weeks to capture a single image.
  • Participants inquire about the actual exposure time for the Deep Field image, with one asserting it was approximately 29 days and mentioning the role of the Fine Guidance Sensor in stabilizing the telescope's focus on targets.

Areas of Agreement / Disagreement

Participants express differing views on the implications of Hubble's angular resolution and sensitivity, with no consensus reached regarding the specific capabilities related to imaging the moon landing sites.

Contextual Notes

Discussion includes assumptions about angular resolution and sensitivity, as well as the dependence on exposure time for imaging faint objects. Specific details about the Deep Field image's exposure time and the function of the Fine Guidance Sensor are mentioned but not resolved.

Space259
Messages
4
Reaction score
0
It's quite simple Physics to show that the moon landing sites cannot be imaged by Hubble as its angular resolution is too small. So how come:

"Prof Steve Beckwith Director Hubble 1998-2005

"we could easily image the light from a firefly at the distance of the moon"

What am I missing here?
 
Astronomy news on Phys.org
Yes. I think the author meant the Hubble can detect the lighting bug at that distance because it is very sensitive. But if there are 2 bugs at that distance and about 100m apart, Hubble will see them as one source of light.
 
Last edited:
pixel01 is correct, but to add:

It is important to remember that cameras can take pictures of dim objects by essentially leaving the shutter open as long as you wish to gather up enough photons to make an image. The Hubble can spend weeks taking a picture of a single object to gather up enough photons to make it detectable.
 
Is weeks how long it took to take the Deep Field image?
 
nanoWatt said:
Is weeks how long it took to take the Deep Field image?

Per my memory, the exposure time for the Ultra DF Image was about 29 days !

One of very important device of the Hubble TS is the Fine Guidance Sensor which is designed to lock the telescope onto the target.
 
http://hubblesite.org/newscenter/archive/releases/2004/07/
 

Similar threads

  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 6 ·
Replies
6
Views
4K
  • · Replies 2 ·
Replies
2
Views
3K
  • · Replies 12 ·
Replies
12
Views
3K
  • · Replies 86 ·
3
Replies
86
Views
9K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 34 ·
2
Replies
34
Views
14K
  • · Replies 3 ·
Replies
3
Views
4K
  • · Replies 24 ·
Replies
24
Views
8K
  • · Replies 9 ·
Replies
9
Views
2K