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Do Telescopes in Space Show Us the Universe When it was Younger Than From Measurements Made From the Earth’s Surface?

-- Randy | December 30, 2020

Question:

When I look at a star I am looking into the past, I get that. But if a star’s photons are captured before they reach earth with a telescope, then the star I see with my eye is farther in the past than the same star I see with a telescope? So the suns rays I see with my eyes is ~8 minutes old, but with a scope would be less than that? For example, if it is said that a exploding star (that cannot be seen with my naked eye) through a telescope is measured at 100 light years away. But that explosion has not really reached earth yet has it? We went out and grabbed those photons with the lens. Did we not alter something there? Sorry so confusing sounding, but I have wondered about this for a long time.
Thank you
Randy
Age 73

-- Randy

Answer:

Technically, yes, but the difference between the point at which a telescope in space, say in orbit around the Earth, captures an image of an astronomical object and that same measurement made with your eye on the Earth’s surface is quite insignificant.  For example, if you measure the light from a star that is one light year away with the Hubble Space Telescope, you would capture the light from the star about 547 kilometers (the Hubble telescope’s average orbital distance above the Earth’s surface) before it reaches the Earth’s surface.  The 547 kilometer difference over that one light year, which is equal to 9.4607×10^(12) kilometers, to the star represents about 58-trillionths, or about 58×10^(-12), of the distance to the star.  This is really not a significant difference in either the distance or the apparent age of the star.

-- Jeff Mangum