Feature request: Distance info about galaxies I'm currently classifying
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I_wish_I_can_study_at_Starfleet_Academy
It would make classifying even more awesome if I can see how far is the galaxy I'm currently looking at. Is there any easy way to fetch the distance info and automatically display it under or above the picture?
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Budgieye
moderator
If you go into SDSS you can get the redshift z, which is how astronomers think in distance. If SDSS doesn't have a redshift, go into NED, and there might be something there.
The current images of galaxies are very distant, about z=0.05 or about 500 million light-years away.
#1 How do I : Find out more information about the galaxy I have classified? http://talk.galaxyzoo.org/#/boards/BGZ0000005/discussions/DGZ0000lv2 Examine, Skyserver, Finding Chart, navigate, NED
Forum: Friday 8th January, 2010. Two galaxies, the same size? by Budgieye http://www.galaxyzooforum.org/index.php?topic=277034.msg416504#msg416504 measure the size and distance of two galaxies
PAGE 2 Galaxy Redshift Chart https://talk.galaxyzoo.org/#/boards/BGZ0000007/discussions/DGZ0000ulp?page=2
7.3 Measure distance https://talk.galaxyzoo.org/#/boards/BGZ0000001/discussions/DGZ0000wrb?page=7
Here are images of galaxies at various distances,
Galaxy Redshift Chart https://talk.galaxyzoo.org/#/boards/BGZ0000007/discussions/DGZ0000ulp?page=2 Galaxy Redshift Chart https://talk.galaxyzoo.org/#/boards/BGZ0000007/discussions/DGZ0000ulp?page=2
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Rick_Nowell
Some great links there; what work! Must have taken months to compile. Just to seriously confuse the issue, there are four ways of measuring distance, though people nearly always use Light Travel Time as it makes the most sense to us. This article from Atlas of the Universe explains the four ways distance can be measured in an expanding universe.
The Distance Scale of the Universe http://www.atlasoftheuniverse.com/redshift.html
Ned Wright's cosmology calculator is used by professionals. http://www.astro.ucla.edu/~wright/CosmoCalc.html If you look at the table on the left, it has various entry boxes. The one labelled z (by default on 3) is where you put the redshift in. Say using redshift z=0.05 and and the option "flat" (we live in a flat universe), among the values it gives in response include the light travel time which is 0.678 Gyr., or 678 million light years.
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For quick back-of-the-envelope estimates I really like the ‘Paper-and-Pencil Cosmological Calculator’ by Sergey Pilipenko.
https://arxiv.org/abs/1303.5961
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Budgieye
moderator
in response to Ghost_Sheep_SWR's comment.
Interesting. If you look at the first page, the apparent size of a galaxy first gets smaller as it is further away, than apparently looks bigger at z=5 as the universe was smaller then, so objects looked bigger as they were apparently closer.
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Ghost_Sheep_SWR
in response to Budgieye's comment.
Yes, so counter-intuitive as nature always seems to be 😃 Or actually we are simply not well-suited to feel at home in nature not close to our scale of existence 😉
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JeanTate
Blame Einstein (et al) ... the change in apparent size is due to the fact that we don't live in a perfectly flat, Galilean universe.
In fact, there are actually several different ways to state "distance" in our universe, and they are all different for objects beyond the Local Group! 😮 There's light travel time distance, apparent size distance, "radar" distance, ... Ned Wright's Cosmology Tutorial is good at explaining all this ... (sorry, can't find a link just now)
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Budgieye
moderator
Good links , I'll add them to the Index to everything. https://talk.galaxyzoo.org/#/boards/BGZ0000001/discussions/DGZ0000wrb
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