The Truth About The Creation 
God's Glory, God's Handiwork, God's Word, The Genesis Account
A Dissertation by Pastor Ed Rice January 2017

13: Measuring The Speed Of Light And Distance to Stars

A couple of essays that have been used to document how we know the speed of light and the distance to stars will be useful in this effort.
Essays in Science – Speed of Light
Five hundred years ago man supposed that light had a measurable speed. The speed of light cannot be seen nor measured by clicking a light switch on, because the speed of light is imperceptibly fast. Today, the speed of light is very accurately measurable. Ole Romer (1644-1710), a Danish astronomer was studying the periodic cycle of one of Jupiter's moons when he calculated the speed of light. Sixty five years earlier, in 1610 Galileo, armed with a 20 power telescope, noticed that Jupiter had 4 moons. Ole Romer was calculating the time it took for one large moon to emerged from Jupiter's shadow. His measurements showed a 40.5 hour period for this moon. As winter set in Ole noticed that the expected rising of Jupiter's moon was getting later and later, gradually changed by 20 minutes. As spring came the rising moon started getting earlier and earlier until it was restored to its original schedule.
Obviously the orbit of Jupiter's moon did not change because the Earth moved further away from Jupiter. It was the speed of light that was taking the extra time to reach the Earth as it traveled from the moon rise on Jupiter. Ole correctly concluded that this time difference was due to the extra distance that the light had to travel to reach Earth. With this information Ole Romer, in 1676, remarkably, calculated the speed of light at 225,000 kilometers per second. Even though he had only rough numbers for the Earth's orbit and Jupiter's orbit, he was only 25% low in his calculations. Today we measure it at 299, 792 kilometers per second. Ole Romer was the first person to demonstrate that the speed of light is measurable. With more accurate instruments and many more observations we can now accurately calculate the speed of light in free space; that is accurate for our little galaxy, without the effect of black holes, relative velocities, rotational dynamics or other limiting errors caused by theories of relativity. The speed of light is thus finite and measurable.
Notice in this treatise the emphasis that the speed of light is measurable in this galaxy and with our current units of time and distance understood without relativity. The genius of Albert Einstein has allowed us to recognize that the speed of light and the time clock that measures it, are not necessarily constants but very flexible and even relative, warped by gravitational forces in space and time. Most of us have heard some of this theory of relativity in the sci-fy stories about intergalactic travel where a person does not age when approaching the speed of light. Einstein's theories of relativity can alter time and distance, the speed of light and even the speed of gravity, which is not yet measured.
Theories about intergalactic travel of light, time dilation or relativity can readily support an idea that out there on the edge of our universe a single day could be as a thousand years, and here in our 'time zone' a thousand years could be as a single day out there. Marvelous possibilities exist for a mere 6000 year old Earth, even with the speed of light 'fixed' at 300,000 kilometers per second and Supernova 87a measured at 168,000 light years away. How did they measure that distance? That's the subject of another essay.
Essays in Science – Measure of Space Distance
It is the glory of God to conceal a thing: but the honour of kings is to search out a matter “ (Prov 25:2). Let's do just that concerning how far away Andromeda or Supernova 87a might actually be. Since it seems immutable that light travels at a finite, albeit very very fast speed, and we view the Andromeda galaxy from a young Earth,1 perhaps the scientists have exaggerated the distances in inter-galactic space. How can you tell how far away a star is anyway?
A distance measure for space can be likened to a ride on a twenty five foot diameter merry-go-round. Board the merry-go-round at night while three birthday candles are placed 50, 500 and 5,000 feet away. Of course the brightness of the candles can first be used to estimate their distance. This brightness measure has been a mainstay of distance determination. A star's absolute luminosity was found to tie directly to a very measurable Cepheid cycle2 and its distance could then be measured via r^2 attenuation of its absolute luminosity. But consider also that as one rotates through revolutions on the merry-go-round and watches the nearest light, they will have to pivot their line of sight back and forth 27 degrees (tan-1 (25/50) degrees); for the second light one will pivot their head only 3 degrees (tan-1 (25/500) degrees); and for the farthest light one will pivot their head only 0.3 degrees (tan-1 (25/5000) degrees). With some precise instruments one could measure these angles and then determine the distance to each flickering candle. Indeed your brain does this sort of calculation every day; your two eyes are spaced roughly 3 inches apart, and their vision crosses at a measured angle which determines the distance you are focused at.
Now consider that from June to December or March to September the merry-go-round that the Earth is riding moves quite a distance in space. By definition we are 1 a.u. (astronomical unit) from the sun, that is 8.317 light minutes or 0.00001581 light-years (1.581e-05 light-years). Just like the distance to the birthday candles can be approximated or carefully measured from the merry-go-round, so too the distance to stars can be approximated or carefully measured from the Earth's orbit.
In 1987 we watched a supernova that was supposedly 10.12 billion a.u. away. So between Dec and June the line of sight to the supernova changed by 0.0004 mili-arc-seconds (mas) or .006 billionths of a degree (tan-1 1/10,120,000,000 degrees). The W.M. Keck II 400 inch telescope in Hawaii can achieve an amazing five mili-arc-seconds spacial resolution.3 Here, however, we needed to measure .0004 mili-arc-seconds, significantly smaller than 5 mas. Obviously we cannot measure these great space distances with these means. The 1989 European Hipparcos space observatory measured this 'parallax' distance for 120,000 stars, but it is only effective for stars within two to three thousand light years.
Going back to our merry-go-round example for birthday candles greater than a mile away one could still perceive various distances by the size and brightness of the flames. We do this based on what we know and observe about the nearer birthday candles at known distances. Some birthday candles may be larger than others and cause slight error in this means of gauging this distance, but this error would be relatively small. In like manner astronomers measure a star's size, emissions, Cepheid variable, and pulsations and can come up with a reasonably accurate distance estimate for deep space stars.
Again in our illustration, if the birthday candles were all set in motion we could judge the distance to any candle by its perceived motion. This is especially true when it is discerned in relation to some known closer birthday candles. Lights clustered together with this perceived motion may be more accurately discerned. A rotation, will likewise more accurately differentiate these distances. This is basically how the calculations of astronomical distances to stars, clusters, and galaxies are accomplished. It is indeed an art in the world of science. Each measurement leans on observations from all three methods. The art does have its sources of error, but over all, the errors will not be orders of magnitude. The 1987 supernova observed within the large Magellanic Cloud is measured (estimated) at 168,000 light years away. Throwing in a plus or minus 10,000 light year error still leaves it a very long distance away. Thus it still begs the question, “Just when did that star explode?” Suffice it to say that time and space warp in the outer regions of God's universe. It does not take light 168,000 years to travel from the large Magellanic Cloud.
It is shown elsewhere in this effort that God can bow the heavens and dilate time as he pleases, just trust him. “He bowed (bowed, streached out, extended, spread … ) the heavens also, and came down: and darkness was under his feet” (Ps 18:9).
1 If the Bible is true, infallible and inerrant as is our presupposition, the Earth was formed in 6 days, just as God said, formed only 6,019 years ago.
2 Georgia State University, “Hyperphysics- delta Cephei” http://hyperphysics.phy-astr.gsu.edu/hbase/astro/cepheid.html (Accessed 06/29/16).
3 The marvelous 200 inch Hale Telescope at the Palomar Observatory had an amazing resolving power of 0.025 arc sec (25 mas) from 1948 to 1993. In 1993 Keck's dual 400 inch telescopes perfected a 5 mili arc second spacial resolution at 2.2 micrometers. California Institute of Technology, www.astro.caltech.edu/palomar/ and www.keckobservatory.org (accessed Nov 2015).


To Continue in this series click the link below:
13: James Ussher's Calendar and Dating Methods. . . 254 www.truthaboutthechrist.com/thetruthaboutthecreation/14ussher_dates.html

God's Glory, God's Handiwork, God's Word, The Genesis Account
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