Astronomy is still changing and it is the oldest science. The changes are new discoveries in the studies of the sky universe, and how humans relate with the celestial bodies. Astronomy studies include the nuclear reactions that take place in stars. The shining star knowledge that answers the question of why stars shine. Astronomy covers all sciences. Astronomy is defined as “the study of objects and matter outside the earth’s atmosphere and of their physical and chemical properties” (Merriam-Webster’s Collegiate Dictionary Tenth Edition).
- The earth is the largest terrestrial planet. Mercury, Venus and Mars are the other rocky, dense planets. They are all smaller in mass than the gas planets, yet far denser.
- Stars shine by their own light, planets don’t.
- Our sun is a star in the Milky Way Galaxy.
- “Planet” is Greek for wanderer. They are large objects that revolve around the sun.
- About 5000 stars can be seen from earth with the naked eye.
Of those 5000 stars you can see in the night sky, only a handful are similar in size to our sun. All the rest are bigger, brighter, and more luminous than our sun.
Stars don’t twinkle - the light from a star passes through the earth’s atmosphere, and the deflection equates to twinkling in our perception.
You can easily learn more by becoming a backyard astronomer. Just think of the times you have or can spend time outside just to stargaze. The longer you observe, the more you see, and that’s only about 5000 stars with just your eyes. Using a telescope or binoculars takes you further of course, into a deeper space of astronomical wonders.
Ancient stargazers who were scientific observers noticed those objects outside the earth’s atmosphere and studied them. Johannes Kepler was a mathematician with poor eyesight. He couldn’t observe because of that, yet he could use his insights with other’s observations. He wondered why planets had motions and why they stayed by the sun. In other words, he was the first to hypothesize the force of gravity. I mention this as an aside for inspiration to get outside and check out the sky objects. It is an astounding activity that fosters quests for more of what is out there, and to learn what is currently considered fact.
People who lived in pre-telescope days also lived in places with relatively dark, undisturbed skies. So, they probably went outside at night and observed the unknown lights in the sky, and theorized away. Certainly many cultures thought of the sky as the area of the gods (Greeks, Romans). All these cultures were astronomers, people trying to make sense of those magnificent objects that were perceived to twinkle and not. Recall the favorite Christmas story about 3 wise men who observed a certain star, and followed divine direction to a child’s birthplace. Not all astronomers doings were recorded so we rely on artifacts and structures that are still standing with what we consider observatories in them to help us imagine what ancient astronomy was like.
Circles of stone, wood, lines or holes have been found that are considered ancient observatories. Certain passageways, windows and other openings in temples and tombs were used to observe the sun and moon and other objects. One such famous place was Stonehenge. It has three concentric circles built from 3 different time periods, and has undergone other changes, but is believed to have been used to observe the sun and moon. The ancient ruins of Machu Picchu has a stone pillar where the sun stands still during the two equinoxes of March 21st and September 21st. There was ceremony during these events,and probably at Stonehenge, too. The Mayan ruins of Chichen Itza have a unique (El Caracol) area that definitely resembles an observatory - a lookout to the heavens. It seems to be aligned with the motions of Venus. The Mayans planned raids and battles around the changing positions of Venus.
So, you see astronomy has always been around in some form or another, it is the oldest of sciences. There were probably more more watchers of the sky before we had electricity and aircrafts, and insulated homes. Now, astronomy is offered as college courses, and probably a requirement for some careers. Surely astronomers of old taught and held classes (Keppler studied under Tycho Brahe), and went to great lengths to test and prove hypothesis. Superstitions and religious beliefs were the mainstay for many people who didn’t think mathematically or scientifically, but that was kind of pre-historic astronomy, ancient astronomy.
Here is a list of easy, familiar astronomy terms that most amateur astronomers know. To be active in stargazing, you just pick up the terminology, and even get a glimpse of the words as objects in the sky.
- Asteroid - any of the thousands of minor planets that orbit the sun.
- Revolution - The orbiting of one object around another.
- Planet - Any of the known large objects that revolve around the sun. The wanderers that don’t include Pluto anymore.
- Star - a self-luminous celestial object.
- Light-year - The distance light travels in a year.
- Astrophysics - Physics applied to extraterrestrial objects.
- Zodiac - The band that lies 9 degrees on either side of the path of the sun on the celestial sphere (ecliptic). There are thirteen constellations in the zodiac. The twelve you already know plus one called Ophiuchus.
- Altitude - The height of a celestial object measured as an angle above the horizon.
- Elongation - The angle in the sky from an object to the sun.
- Constellation - An area of the sky containing a pattern of stars named for a particular object, animal or person.
There are many more astronomy terms that are useful when observing and studying the sky and its content. They aren’t necessary to practicing the outdoor activity of wondering, searching, questioning, and answering what the curious activity of a falling star, or a patch of light means to us on earth. All it takes is getting out there and reaching for the stars so to speak.
Main source - In Quest of the Universe, Karl F. Kuhn
Photo credit - El Caracol, author Wolfgang Sauber, wikimedia creative commons