Parallax
The starmap of Hipparchus established the coordinates for about 850 stars. His map did not include parallax measurements This would not begin until 1840 when parallax was measured for three stars: 61 Cygni by F. W. Bessel, Vega by Wilhelm Struve, and Alpha Centauri by Thomas Henderson. The significance of having parallax measurements was not merely to distinguish these stars from the background stars. Halley had already done this in 1718 by identifying three stars ( Sirius, Procyon, and Arcturus) that had moved in relation to background stars. A parallax measurement establishes the distance to the star. By 1900 about 90 of the brightest stars had parallax measurements and therefore known distances.
I have not yet found a source for parallax advancements for the early 20th century so let me jump ahead. The Hipparcos Catalog, a high-precision catalog of more than 118,200 stars, was published in 1997. The lower-precision Tycho Catalogue of more than a million stars was published at the same time, while the enhanced Tycho-2 Catalogue of 2.5 million stars was published in 2000. Hipparcos‘ follow-up mission, Gaia, was launched in 2013. Gaia increases the number of stars with parallax measurements to a billion.
Bessel, Struve, and Henderson |
1840 |
3 stars |
1900 |
90 stars |
|
Hipparcos Catalogue |
1997 |
118,200 stars |
Tycho-2 Catalogue |
2000 |
2.5 million stars |
Gaia Catalogue |
2013-2018 |
1 billion stars |
With this great progress, it might seem that the reach was also immense. However, the reach of parallax is limited to our galaxy, the Milky Way, and not the entire galaxy. Figure 1. illustrates the reach.
Figure 1. The Limits of Parallax ESA/Hubble
The left half of Figure 1 shows the bottom right quarter of the Milky Way galaxy. The largest dashed circle shows the current domain for parallax.
The Gaia Project collects among other things parallax measurements, repeated coordinates of position, luminosity, and color. See the video from the first release of data which shows the motion of two million stars of the Milky Way Galaxy projected for the next five million years.
David Shaw
What is your view?
Video of the Rise and Fall of the Universe-Cosmos
David Shaw
What is your view?
Astronomer Claudius Ptolemy
Claudius Ptolemy (c. 100-170 AD) was a Roman astronomer, astrologer, geographer, musicologist, and opticologist. He worked in Alexandria, Egypt. Little else is known about his life. Ptolemy’s Almagest is the only surviving comprehensive ancient treatise on astronomy. It served as the guide for astronomers and students of astronomy for some 1300 years until Copernicus published his Revolutions of the Celestial Spheres in 1543.
The only hope for survival an astronomer who lived before Ptolemy had was to be incorporated within the Almagest. Of interest is Hipparchus’ star map that included the positions of about 850 stars. Ptolemy included Hipparchus’ data and increased the number of stars in the collection to 1,022. This resource was available for any interested person to do a comparative study of the positions of stars observed by Hipparchus (c. 190 – c. 120 BC) with their own observations.
The intellectual climate was not encouraging for anyone reporting differences between the original data and current observations. This would indicate instability in the heavens. Copernicus feared the consequences of moving the Earth from the center of the universe. He consented to publication of his Sun-centered universe only on his deathbed.
The intellectual climate had changed within certain countries after the Protestant Reformation especially England and the Netherlands. King Charles II
granted a charter to the Royal Society of London for Improving Natural Knowledge in 1663. The society’s motto is Nullius ad verbum, take nobody’s word for it. It expresses a determination to resist the domination of authority and to verify all statements by an appeal to facts determined by experiment.
Edmond Halley participated in this society and financed the publication of Isaac Newton’s Principia Mathematica in 1687. Among Halley’s other accomplishments was his presentation of the first evidence against the solid sky in 1718. He compared Hipparchus’ positions of stars with his own observations and found three stars out of place: Procyon, Arcturus, and Palilicium (Aldebaran). If it were not for Hipparchus’ star map preserved in Ptolemy’s Almagest Halley would not have had an ancient reference with which to compare his observations.
David Shaw
What is your view?
Cosmos is no longer the Universe
Cosmos was the divine intention of creation. For over two thousand years, the universe was viewed as an eternal work of art. Cosmos was the universe. The universe was seen as eternal. It had no history. The four revolutionaries of modern science and Edmond Halley have crushed this view in principle. The progress of science since then has given us an entirely different universe, a universe in development, a universe with a history, a universe that is not a cosmos. But what has become of the stories of creation, the Hebrew story and the Greek story? They were written when the universe was seen as a cosmos. Can they be our guide or inspiration today?
Beginning with Pythagoras the universe was given a new theological name that acknowledged the divine order of the universe. Before Pythagoras, cosmos was a simple word meaning order with no theological implications.
Scientists have been led to reject scientific theories based on a final cause. Detectives, however, seek to find motives which are final causes to prove their cases. Plato responding to the question “what are the greatest things?’ said, there are two great things the cosmos and the city-state. Plato had several examples of community to observe. He did not have to speculate about what community could be. He was aware of the flaws in these communities. Yet he found them to be similar to the cosmos at the human level. The cosmos/universe = city-state/humans. Cosmos was the order of the universe. The city-state was the order of humans.
What has this to do with creation?
If creation deals with establishing a cosmos then creation is a past event. If creation deals with our developmental universe then creation is a forward-oriented final cause.
In an attempt to begin the debate on what the divine idea of creation might be, I have proposed community as cosmos. See chapter 6.3 of The Rise and Fall of the Traditional Theories Of Creation, Community As Cosmos. I give four reasons supporting community as the divine idea of creation.
David Shaw
What is your view?
Our Universe Compared with the Preceding Cosmoses
The Babylonians, Egyptians, Hebrews, and Greeks all believed that the universe was eternal. What’s wrong with that? An eternal universe puts creation in the distant past and leaves no room for human participation in creation.
| Previous Cosmoses | Our Universe | |
|---|---|---|
| Has a beginning | Yes | Yes |
| Has an ending | No | Yes |
| Has a history | No | Yes |
David C. Shaw
What is your view?
Science’s mistake
Science has had a decisive role is demolishing the ancient cosmos. Copernicus, Kepler, Galileo, Newton, and Halley have joined together to leave the cosmos in fatal tatters. I am not an expert on these scientists, but I doubt that any of them were conscious of what they had done. I can’t recall any of them leaving a written mention of the word cosmos describing what the word meant. Even in our own time, we are entertained by the TV series COSMOS which appears to be unaware that cosmos is a theological term. Carl Sagan explained within the series that cosmos is a simple word for order. If this were true cosmos could not be a synonym for universe.
Sagan made no mention of Pythagoras who was the first to apply the word cosmos to the universe. Plato and Aristotle acknowledged Pythagoras and added definitions to the cosmos:
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the planets moved in perfect circles;
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beginning with the sphere of the moon and outwards the universe was made of eternal matter;
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the Earth stood at the center of the cosmos;
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the stars are equally distant from Earth;
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the motion of bodies on Earth was explained in terms of the four elements, earth, water, air, and fire.