# Identification of celestial objects and observable universe

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When a new planet or a star is discovered how do the scientists keep a track on their identities as there are billions of them?........(Just a question out of curiosity).....Does the observable universe keep on expanding....and if we can see more than 13.772billion light years(estimate) would that practically verify that the universe is expanding faster than light or is there anything else which proves it?

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1 hour ago, Heisenberg1927 said:

When a new planet or a star is discovered how do the scientists keep a track on their identities as there are billions of them?

There are various catalogs of stars and galaxies: https://en.wikipedia.org/wiki/Astronomical_catalog

1 hour ago, Heisenberg1927 said:

Does the observable universe keep on expanding....and if we can see more than 13.772billion light years(estimate) would that practically verify that the universe is expanding faster than light or is there anything else which proves it?

The observable universe is expanding.

Note that it doesn't really make sense to say that the universe is "expanding faster than light". Expansion is a scaling effect not a speed. The speed at which two points move apart is proportional to how far apart they are (this is Hubble's Law). So there are always objects that are far enough apart that they are moving apart at the speed of light or, if they are twice as far apart, twice the speed of light, or whatever. We can see objects that are moving away from us at more than the speed of light.

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I appreciate your reply...so for visualisation's sake can I imagine the universe to expand from every point in space/time..?

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42 minutes ago, Strange said:

There are various catalogs of stars and galaxies: https://en.wikipedia.org/wiki/Astronomical_catalog

The observable universe is expanding.

Note that it doesn't really make sense to say that the universe is "expanding faster than light". Expansion is a scaling effect not a speed. The speed at which two points move apart is proportional to how far apart they are (this is Hubble's Law). So there are always objects that are far enough apart that they are moving apart at the speed of light or, if they are twice as far apart, twice the speed of light, or whatever. We can see objects that are moving away from us at more than the speed of light.

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54 minutes ago, Heisenberg1927 said:

I appreciate your reply...so for visualisation's sake can I imagine the universe to expand from every point in space/time..?

Yes, every point is moving away from every other point (on large enough scales).

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1 hour ago, Heisenberg1927 said:

I appreciate your reply...so for visualisation's sake can I imagine the universe to expand from every point in space/time..?

No matter where we were in the universe, we would be the at the center of our observable expanding universe. The expansion though is only happening over the larger scales of the universe. Over smaller denser regions, such as our local group of galaxies and even beyond, expansion is overcome by gravity.

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