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Top Document: [sci.astro] Stars (Astronomy Frequently Asked Questions) (7/9) Previous Document: G.11 How far away is the farthest star? Next Document: Copyright See reader questions & answers on this topic! - Help others by sharing your knowledge Author: Joseph Lazio <jlazio@patriot.net> In general, no. The reason is that stellar distances are so large. Over human time spans, the typical velocity of a star is so low that its distance does not change appreciably. Let's consider a star with a velocity of 10 km/s, typical of most stars. In 1000 yrs, this star moves about 300 billion kilometers (or 3E11 km). Suppose the star is 100 light years (about 1E15 km or 1 quadrillion kilometers) distant. Thus, in 1000 yrs, the star moves about 0.03% of its distance from the Sun. This is such a small change, it's not worth worrying about it. The situation is even more extreme in the case of galaxies. Typical galaxy velocities might be hundreds to thousands of kilometers per second. However, their distances are measured in the millions to billions of light years. User Contributions:Comment about this article, ask questions, or add new information about this topic:Top Document: [sci.astro] Stars (Astronomy Frequently Asked Questions) (7/9) Previous Document: G.11 How far away is the farthest star? Next Document: Copyright Part0 - Part1 - Part2 - Part3 - Part4 - Part5 - Part6 - Part7 - Part8 - Single Page [ Usenet FAQs | Web FAQs | Documents | RFC Index ] Send corrections/additions to the FAQ Maintainer: jlazio@patriot.net
Last Update March 27 2014 @ 02:11 PM
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[sci.astro] Stars (Astronomy Frequently Asked Questions) (7/9)
Section - G.12 Do star maps (or galaxy maps) correct for the motions of the stars?
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[sci.astro] Stars (Astronomy Frequently Asked Questions) (7/9)
Section - G.12 Do star maps (or galaxy maps) correct for the motions of the stars?
( Part0 - Part1 - Part2 - Part3 - Part4 - Part5 - Part6 - Part7 - Part8 - Single Page
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with stars, then every direction you looked would eventually end on
the surface of a star, and the whole sky would be as bright as the
surface of the Sun.
Why would anyone assume this? Certainly, we have directions where we look that are dark because something that does not emit light (is not a star) is between us and the light. A close example is in our own solar system. When we look at the Sun (a star) during a solar eclipse the Moon blocks the light. When we look at the inner planets of our solar system (Mercury and Venus) as they pass between us and the Sun, do we not get the same effect, i.e. in the direction of the planet we see no light from the Sun? Those planets simply look like dark spots on the Sun.
Olbers' paradox seems to assume that only stars exist in the universe, but what about the planets? Aren't there more planets than stars, thus more obstructions to light than sources of light?
What may be more interesting is why can we see certain stars seemingly continuously. Are there no planets or other obstructions between them and us? Or is the twinkle in stars just caused by the movement of obstructions across the path of light between the stars and us? I was always told the twinkle defines a star while the steady light reflected by our planets defines a planet. Is that because the planets of our solar system don't have the obstructions between Earth and them to cause a twinkle effect?
9-14-2024 KP