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Bolik

Why can't nasa take pictures of exoplanets

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Ok, so this question is bugging me so bad. We can take hq, actual pictures of galaxies that are millions of lightyears away, but we cant take pictures of exoplanets that are super close, for example proxima centauri b. Why is this the case? I understand that size can get in the way, but I doubt that this is the reason.

I mean this is the best picture of exoplanet we have (the white dot):

https://blog.nationalgeographic.org/wp-content/uploads/2014/05/13-04215-large-gemini.jpg

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Exoplanets are extremely small, extremely faint and very close to the star they are orbiting. There is currently no physical way to image these objects.

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8 minutes ago, Mr Spock said:

Exoplanets are extremely small, extremely faint and very close to the star they are orbiting. There is currently no physical way to image these objects.

thank youuu

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Train your camera on a streetlight 5Km away or however far it takes till the streetlight is as small as a star visually and, try grabbing an image of the little insect circling the light.

Edited by Sunshine
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Comparing exoplanet to distant galaxy is comparing apples to oranges.

Distant galaxy is very, very (repeat about 200 times), very large, and although it is very, very (again apply repeater) far away, it is about angular size - for most galaxies size to distance ratio is such that they form angular image in sky that can be readily observed or imaged. Planet on the other size is much smaller in radius compared to distance - which means single dot at best.

Then we come to issue of light - galaxy emits a lot of light (and other EM radiation) - it is billions of stars of light emitted. Planet on the other hand does not emit any light at all - it only reflects light from a local star. It is sooo faint compared to most of galaxies that are imaged and observed. How much fainter? Million of times fainter, or more (in apparent brightness, in absolute terms probably 10 to the power of 1000 or who knows :D ).

Third problem is as mentioned above - trying to image / observe light of a candle next to light house shining in your face - very hard thing to do.

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The answer is resolution. Galaxies are 100's of thousands of lights years in diameter, so even 100's of millions of light years away they still have a large diameter in the sky compared to a planet orbiting a star. Resolution is limited by the diameter of the telescope, the Hubble mirror has a relatively small diameter so doesn't have the resolution to separate an exoplanet from its star. The new ELT being built at the moment has a 40m diameter compared to the 2.4m mirror in the Hubble, so it should be able to image exoplanets in more detail than ever before.

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Some exoplanets have been imaged directly, like Fomalhaut b. The link JBracegirdle provides has some excellent other examples.

But I think you underestimate the enormous distances involved when it comes to observing exoplanets. As others have said, these planets orbit extremely luminous stars at a distance of only a few astronomical units. As you can see on most images of these exoplanets, like HR 8799 and Fomalhaut b, a trick has to be applied to block out the light of the star to make the tiny planet visible.

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I'm currently watching an episode of Horizon first broadcast 23/10/2016 and about 35 minutes in they are with someone taking images of an exoplanet. The episode is about weather on other planets. Titles "The wildest weather in the Universe"
Michael

 

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