June 9, 2017
Thanks to Alissa Simon for today's post.
In the Syntopicon (Astronomy and Cosmology chapter), Mortimer Adler notes that “Man has used astronomy to measure not only the passage of time or the course of a voyage, but also his position in the world, his power of knowing, his relation to God. When man first turns from himself and his immediate earthly surroundings to the larger universe of which he is a part, the object which presses on his vision is the overhanging firmament with its luminous bodies, moving with great basic regularity and, upon closer observation, with certain perplexing irregularities. Always abiding and always changing, the firmament, which provides man with the visible boundary of his universe, also becomes for him a basic, in fact, an inescapable, object of contemplation.” While this quote attempts to encapsulate stars' effect on the human imagination, it is still rather difficult to ascertain what exactly we feel when we gaze up at the heavens.
Astronomers are now able to gather data from such distances as boggle the mind. And at each turn, more questions arise. We wonder about human existence, about our fragility or stability, about life itself, and also about the supernatural. Somehow the vastness of space, the clarity of stars, and the unknowable processes of galaxies grab our imagination in a powerful way. This does not necessarily lead to questions of deities, but rather to our place among the vast and complex unknowns. For example, Lucretius invites contemplation of the heavens to inspire freedom from all constraints (such as religion). Ironically, for Lucretius, seeking vast unknowns can simultaneously turn our vision inward into a realm of peace.
However, in Plato, Timaeus says “Had we never seen the stars, and the sun, and the heaven, none of the words which we have spoken about the universe would ever have been uttered.” For Timaeus, then, humans seek definitions. Words define our borders, which in turn, also allows us to approach the supernatural.
Imagining the non-existence of space is impossible for me. It would be as if the earth had no water. I am not sure if the stars exist solely to spark our imagination, or if they are meant to serve some higher purpose. All I know is that time spent looking at the heavens is never wasted.
Over the next few weeks, this blog will host a variety of astronomical images. All of the images and information come from Richard Johnson, amateur astronomer. We are indebted to Richard for compiling these wonderful images to further spark our imagination. A few textual citations from ancient astronomers will be sprinkled throughout. We hope you enjoy.
- The Andromeda Galaxy (M 31) is the nearest spiral galaxy to our own Milky Way Galaxy being only 2.5 million light years (mly) from Earth. This nearby galaxy is a huge aggregation of stars, gas, and dust which allows us to study all the features of our own galaxy that we cannot observe because we are inside it. Although Andromeda is the largest galaxy of the local group, it may not be the most massive. Recent findings suggest that the Milky Way Galaxy contains more dark matter, implying that it is much denser than M 31. Observations by the Spitzer Space Telescope in 2006 revealed that M 31 contains one trillion stars, several times the number of our galaxy (estimated at 300 to 400 billion). The Andromeda Galaxy is approaching the Milky Way, and the two are expected to collide in about 2.5 billion years. A likely outcome of the collision is that the galaxies will merge to form a giant elliptical galaxy - a common event in large galaxy groups. The rate of star formation in the Milky Way is much higher than the Andromeda Galaxy. The rate of supernovae development in the Milky Way is also double that of the Andromeda Galaxy. This suggests that M 31 experienced a great star formation phase, but is now in a relative state of quiescence, whereas the Milky Way is experiencing more active star formation.
- M 101 Pinwheel Galaxy (NGC 5457) is a very large, relatively nearby, face-on spiral galaxy. M 101 is located in the constellation Ursa Major, at a distance of about 27 million light years from Earth as determined from the Hubble Space Telescope observations. M 101 is a large galaxy with a diameter of 170,000 ly, comparable in size to the Milky Way Galaxy. The galaxy is remarkably asymmetric due to the tidal forces from interactions with its companion galaxies, with its core considerably displaced from the center of its disk. Another remarkable property of this galaxy is its large number of star-forming H II regions. H II regions are enormous clouds of high density molecular hydrogen gas, ionized by large numbers of hot, bright, young stars forming within them.
- The Whirlpool Galaxy (M 51, NGC 5194) is one of the most conspicuous and best-known spiral galaxies in the sky. M 51 is located in the constellation Canes Venatici about 28 million light years (mly) from earth (distance estimates ranging from 15 and 35 mly). M 51 is interacting with its much smaller neighbor, NGC 5195. Visually, the two systems appear to be actually connected. However photographs of the system reveal that they are not connected as the dark dust lanes of the large spiral curve in front of the companion. It is thought that a black hole surrounded by a ring of dust exists at the heart of the spiral. The Whirlpool Galaxy reaches high altitudes throughout the northern hemisphere making it an accessible observing target from the early hours in the winter through the end of the spring season.
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