Questions related to the phenomenon whereby electromagnetic radiation (such as visible light) generated by an object moving away from an observer will have increased in wavelength (i.e. shifted toward the red end of the spectrum) once it reaches the observer.

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1answer
216 views

How distances are measured in the Solar System, in the Galaxy, and in the Universe?

Distances in our universe can be calculated in several ways: Stellar Parallax Standard Candles Redshift How are these methods linked, and how they are actually used to calculate distances are ...
11
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3answers
150 views

Is it possible to measure galactic red shift using consumer telescope equipment?

I was wondering if it would be possible to measure red shift from distant galaxies using consumer grade telescope equipment and spectroscopy filters. (like this one) I imagine it would require a ...
6
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2answers
164 views

Does matter accumulate just outside the event horizon of a black hole?

My understanding is that time slows and approaches stopping when approaching the event horizon of a black hole. I have seen this explained several places, including a brief explanation in the last ...
6
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1answer
91 views

How does gravity affect the wavelength of light?

If, hypothetically, me and my rocket powered flashlight were falling straight toward the center of a black hole. The flashlight is a few kilometers behind me in our travels toward the center of the ...
5
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3answers
65 views

Heavy star and redshift

A heavy star should look redshifted, due to gravitational time dilation. How is that incorporated into the calculations of distances to the stars, or is it negligible? How about an entire region of ...
5
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2answers
145 views

Why do we have the cosmological constant?

Since the cosmological constant is not required to explain that the universe seem to be expanding, why do we have it? What other factors cause us to have that constant? Background: Without the ...
5
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1answer
107 views

Might the universe be really small yet seem infinite from spherical reflections? [closed]

if a single source of light quite small, was placed somewhere inside a completely reflective sphere, quite large, what would the reflections look like from the light source's point of view within that ...
3
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1answer
62 views

Dark Energy Expansion

The new Cosmos extra features mentions that at about 6,771,500,000 years ago the universe began an accelerated expansion. How do we know this? What evidence do we have for this renewed and accelerated ...
3
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1answer
78 views

Is there another explanation, apart from the doppler effect, for the redshift observed in distant galaxies?

On episode 10 of the original Cosmos TV series, Carl Sagan mentions that some scientist don't agree that the redshift observed in distant galaxies is evidence of the big bang, stating that probably ...
2
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1answer
42 views

Data for red-shifting

I am looking for basic data regarding red-shifting that comes with reliable measure of distance of the emitting star.
2
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2answers
44 views

how does redshift prove expansion is accelerating?

My astronomy teachers never would answer this for me... Redshift obviously indicates an object (such as another galaxy) is moving away, but how do we know its acceleration from this? It's my ...
2
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1answer
74 views

Is the expansion accelerating or Decelerating?

According to Hubble's Law, the farther a galaxy is, the farther it is moving away. But do we take into account the fact that we are actually looking in the past? For example, there are two galaxies A ...
2
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2answers
82 views

Conundrum involving distance to object, universal expansion, age of universe, etc

I was recently reading about a galaxy or quasar (not sure which, so lets just say quasar) where the estimated distance to this thing was some very significant fraction of the age of the universe. ...
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2answers
48 views

Can redshift be measured using fourier?

Are there pictures that contain high enough dynamic width, so that amateurs can use fourier spectrum analysis to observe the redshift themselves? I know pictures usually are encoded using RGB and/or ...
0
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3answers
60 views

Basic celestial data

complete beginner here, only got into star gazing a few days ago using my friend's telescope and I don't really understand at all what any of the measurements mean. Anyway, talk about jumping in the ...
0
votes
1answer
79 views

How do we find the exact temperature of a star/galaxy?

This is a very basic question, but I am a little confused. As far as I know, the temperature of a star is analyzed based on the color of the light it emits. So, if a star is moving away from us, then ...
0
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1answer
29 views

Do contracting objects show redshift?

If we consider a point on the central part of a contracting object as observed from earth, the point is continuously moving away from us as the object contracts. Moreover, light emerges from a deeper ...
0
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1answer
34 views

Is there a radius inside of which objects are (doppler) blue shifted?

The Andromeda galaxy is about 600,000 light years away and is doppler blue-shifted. Are there objects closer to us than Andromeda which are red-shifted? Are there objects farther than Andromeda that ...