Explore the Night Sky with an Online Planetarium at Astronomy-Page.com

  • Context: Undergrad 
  • Thread starter Thread starter Art
  • Start date Start date
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Discussion Overview

The discussion revolves around the use of online planetarium tools for stargazing and the implications of distance calculations in the universe on the necessity of dark matter for galaxy formation. Participants share resources and explore the relationship between gravitational mass and visible matter in galaxies.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant shares a link to an online planetarium that allows users to identify stars and galaxies based on their location and time.
  • Another participant questions whether incorrect distance calculations in the universe could eliminate the need for dark matter in explaining galaxy formations.
  • Some participants assert that dark matter is still necessary for galaxies to have significantly more gravitational mass than what is visible, which is essential for their stability during rotation.
  • A participant raises a point about the inverse square law of gravity, suggesting that if distances were smaller than currently thought, gravity might still be sufficient to hold galaxies together.
  • A participant identifies themselves as the webmaster of the astronomy-page.com and mentions their ability to reproduce and modify the planetarium software under GPL.

Areas of Agreement / Disagreement

Participants express differing views on the implications of distance calculations for dark matter's necessity, indicating that the discussion remains unresolved with multiple competing perspectives.

Contextual Notes

There are assumptions regarding the accuracy of distance measurements and their impact on gravitational theories that remain unaddressed. The discussion also touches on technical aspects of software installation that are not fully explored.

Who May Find This Useful

Individuals interested in astronomy, stargazing tools, and the theoretical implications of dark matter in galaxy formation may find this discussion relevant.

Art
Here's a link to a site which is great for beginners such as myself. You can set it for your own location and time. It identifies the stars and galaxies you can see at any moment looking in different directions. http://www.astronomy-page.com/open_planetarium.php

btw out of curiosity and probably a daft question but if the methods used to calculate distances in the universe were wrong and distances are smaller than thought would this nullify the need for dark matter to explain galaxy formations?
 
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There is also this http://www.fourmilab.ch/skyscrsv/ planerarium screensaver which shows you the sky for the current time.

No it's still necessary for Galaxies to have 10-100x as much gravitiational mass than we can see as visible stars. This is necessary for the galaxy to hold together as it rotates.
Forming galaxies in the first palce is a whole different problem.
 
mgb_phys said:
There is also this http://www.fourmilab.ch/skyscrsv/ planerarium screensaver which shows you the sky for the current time.

No it's still necessary for Galaxies to have 10-100x as much gravitiational mass than we can see as visible stars. This is necessary for the galaxy to hold together as it rotates.
Forming galaxies in the first palce is a whole different problem.
Looks interesting. Any idea what folder you need to copy the screensaver into in Vista in order to run it?

Isn't gravity inversely proportional to the square of the distance? So if the distances were less than thought wouldn't gravity based on known masses suffice to hold galaxies together in their formations?
 
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Thank you Art :D, it's nice of you to say that, i really appreciate it. (FYI I'm the webmaster of astronomy-page.com, and it so happens that I found this page completely by chance!) I didn't actually develop the planetarium myself, but it's under GPL so I can reproduce and modify it if I like. All the rest is mine!
 

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