https://astronomy.stackexchange.com/questions/54499/shouldnt-very-very-distant-objects-appear-magnified Stack Exchange Network Stack Exchange network consists of 183 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers. Visit Stack Exchange [ ] Loading... 1. + Tour Start here for a quick overview of the site + Help Center Detailed answers to any questions you might have + Meta Discuss the workings and policies of this site + About Us Learn more about Stack Overflow the company, and our products. 2. 3. current community + Astronomy help chat + Astronomy Meta your communities Sign up or log in to customize your list. more stack exchange communities company blog 4. 5. Log in 6. Sign up Astronomy Stack Exchange is a question and answer site for astronomers and astrophysicists. It only takes a minute to sign up. Sign up to join this community [ano] Anybody can ask a question [ano] Anybody can answer [an] The best answers are voted up and rise to the top Astronomy 1. Home 2. 1. Public 2. Questions 3. Tags 4. Users 5. Unanswered 3. Teams Stack Overflow for Teams - Start collaborating and sharing organizational knowledge. [teams-illo-free-si] Create a free Team Why Teams? 4. Teams 5. Create free Team Teams Q&A for work Connect and share knowledge within a single location that is structured and easy to search. Learn more about Teams shouldn't very very distant objects appear magnified? Ask Question Asked yesterday Modified today Viewed 32k times 28 $\begingroup$ My understanding of the expansion of space itself is very shaky, but if space itself is expanding, then shouldn't very very distant objects appear magnified? For example these James Webb Space Telescope (JWST) galaxies from like the year 400M. Perhaps the distance at which that effect would become noticeable is past the observable horizon. I guess a related question would be What was the scale of space back then compared to now? * cosmology * expansion Share Follow edited yesterday GrapefruitIsAwesome's user avatar GrapefruitIsAwesome 1,75499 silver badges3131 bronze badges asked yesterday orion elenzil's user avatar orion elenzilorion elenzil 38311 gold badge33 silver badges55 bronze badges New contributor orion elenzil is a new contributor to this site. Take care in asking for clarification, commenting, and answering. Check out our Code of Conduct. $\endgroup$ 1 * $\begingroup$ Yes. It's Katie Mac's favoriete weird astronomy fact. $\endgroup$ - Roald 4 hours ago Add a comment | 2 Answers 2 Sorted by: Reset to default [Highest score (default) ] 42 $\begingroup$ Yes. And they are! This is called the "Angular diameter distance turnaround" (or turnover). In the usual model for expansion $\Lambda CDM$, it is at a redshift of about 1.5 or about 15 billion light-years (corresponding to a light travel time of about 10 billion years, or about 4 billion years after the big bang, the distance is greater due to the expansion of space) I'm using rounded values here, because the actual distance is quite sensitive to the exact parameters of expansion. A galaxy from 400 million years after the big bang (a distance of 32 billion light-years) would look as big as a galaxy that is 2.7 billion light-years away. (These figures from Ned Wright's calculator) It's illustrated in this xkcd comic. You can see nearby "galaxies" are large and bright, more distant galaxies are smaller, very distant galaxies are large, dim, and red. More details about this phenomena are answered by Understanding The Turnover Point of Angular Diameter Distance Share Improve this answer Follow edited yesterday answered yesterday James K's user avatar James KJames K 111k55 gold badges275275 silver badges389389 bronze badges $\endgroup$ 0 Add a comment | -1 $\begingroup$ Imagine the universe as a ballooning sphere. Like the surface of an inflating balloon, objects on it drift apart. Similarly, as the universe expands, galaxies grow more distant. This expansion reshapes our view of faraway objects. The "Angular diameter distance turnaround" denotes a juncture where distant entities seem larger due to universal expansion. In the LCDM model, it emerges at roughly 15 billion light-years from us, a result of light speed and cosmic growth interaction. For instance, a galaxy born 400 million years post-big bang might now be 32 billion light-years away, yet seem as large as one 2.7 billion light-years away. This results from light journeying longer through expanding space, magnifying its apparent size. Illustrated charmingly in an xkcd comic, it portrays nearby galaxies as luminous and grand, distant ones as smaller, and very remote galaxies as vast, dim, and reddish. For deeper insights, delve into "Understanding The Turnaround Point of Angular Diameter Distance." The universe's expansion remarkably shapes our cosmos perception! When observing distant universe features, we peer into the past due to light's travel time. Universe expansion, likened to a ballooning analogy, means galaxies are moving apart over time. This expansion stretches light from faraway galaxies as it travels, leading to longer wavelengths, known as redshift. Greater distance means more redshift, causing very distant galaxies to appear redder. The "Angular diameter distance turnaround" marks a specific point where redshift and space expansion blend, making distant objects seem magnified. This happens as space's expansion counteracts the increased light travel distance. In the LCDM model, the prevailing cosmic framework, dark energy and dark matter influence the expansion. About 15 billion light-years away (corresponding to a redshift of 1.5), expansion and redshift result in the "turnaround" point. Beyond it, objects appear larger due to these combined factors. This idea is vividly conveyed in an xkcd comic: closer galaxies are larger and brighter, distant ones smaller, while very remote galaxies are larger yet dimmer and redder. For profound insights, delve into resources on the "Understanding The Turnaround Point of Angular Diameter Distance." These shed light on how universal expansion molds our perception of the cosmos. Share Improve this answer Follow answered 2 hours ago Third Eye's user avatar Third EyeThird Eye 1 New contributor Third Eye is a new contributor to this site. Take care in asking for clarification, commenting, and answering. Check out our Code of Conduct. $\endgroup$ 1 * $\begingroup$ Hello Third eye. You seem to have rewritten my answer. I don't see any significant additions, you even use the same rounding of values as my answer. Please feel free to write your own answer, but don't just plagiarise mine. $\endgroup$ - James K 5 mins ago Add a comment | You must log in to answer this question. Not the answer you're looking for? Browse other questions tagged * cosmology * expansion . * Featured on Meta * Moderation strike: Results of negotiations * Our Design Vision for Stack Overflow and the Stack Exchange network * Astronomy Stack Exchange 10-year anniversary! Linked 15 Understanding The Turnover Point of Angular Diameter Distance Related 2 Do gravitationally bound (e.g. orbiting) objects really resist the expansion of space? 0 Any theories about universal expansion due to action at the universal event horizon? 9 Could there really be a preferential direction to the speed of light? 5 If we watched extremely red-shifted galaxies near the edge of the observable universe for a very long time, how would they change? Would more appear? 2 Because the Universe is expanding, what is it taking up? 4 Why do we see a cosmological redshift at all if space is not expanded in our solar system? 17 Is there physical evidence to distinguish between the expansion of space and an anthropocentric universe? 3 Redshift distance proportionality at high Z and need for "mighty mouse" galaxies? 1 Would an observer standing at the edge of the "observable universe" perceive the expansion of space-time? 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