How much in the past do we see these planets?

In summary, scientists use various methods such as radiometric dating, geological features, and chemical analysis to determine the age of planets. The farthest we can see into a planet's past depends on its distance from Earth, but we can only see a portion of its history. The formation of planets can take millions or billions of years, but we can only see a small portion of this process due to the limitations of light speed. Studying the past of planets can provide insight into the formation of our own planet and solar system, the potential for life on other planets, and the evolution of the universe.
  • #1
Dreksler
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This infrared image shows planets that are orbiting a star called HR 8799, since these are thermal emissions does it still mean planets here that we see are 129 years in the past?
The HR 8799 star is 129 light-years away from us, in this image we can see thermal emissions coming from these planets. Do these emissions move at the speed of light? If so does it mean that what we are seeing in this image is how the planets looked like in infrared 129 years in the past?
 

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  • #2
Infrared is electromagnetic radiation, just like visible light (it just has a different wavelength), so yes and yes.
 
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Thank you!
 
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1. How do we determine the age of the planets we see in the past?

The age of a planet is determined by analyzing the composition of its rocks and using radiometric dating techniques. Scientists can also estimate the age of a planet by looking at the age of its parent star.

2. Can we see all the planets in the past at the same time?

No, we cannot see all the planets in the past at the same time. The light from each planet takes a different amount of time to reach us, depending on its distance from Earth. This means that we see each planet at a different point in its history.

3. How far back in time can we see planets?

The farthest back in time we can currently see planets is about 13.8 billion years. This is because the universe is estimated to be about 13.8 billion years old and the light from the furthest objects in the universe takes that long to reach us.

4. Can we see the planets in their current state or how they were in the past?

We see the planets as they were in the past, not in their current state. This is because the light from these planets takes time to reach us, so we are essentially looking back in time when we observe them.

5. How does the distance between Earth and the planet affect how far back in time we can see it?

The distance between Earth and a planet does not affect how far back in time we can see it, but it does affect how clearly we can see it. The further away a planet is, the fainter it appears to us and the harder it is to gather information about it.

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