The nice thing about choosing a theme that begins with the letter A is that I can use it as the first post and give you all a little introduction to what Astronomy is exactly. Nice, right?
So, what is Astronomy?
Astronomy, or “the law of the starts”, is the science, or study, of celestial objects, like stars, planets, galaxies, moons, asteroids, comets, and nebulae. Astronomy is concerned with the physics, chemistry, and evolution of these objects, and just about anything that happens outside of Earth’s atmosphere.
In recent history Astronomy was broken into two branches. Observational astronomy is focused on gathering data while Theoretical astronomy is focused on using computer models to describe and predict celestial phenomena. The two fields complement each other, with the theoretical astronomy seeking to explain the observational side, and observations being used to confirm theoretical predictions.
Cosmology is a related subject that is concerned with the study of the universe as a whole. I think that the two subjects are so closely related that the distinction is unnecessary, at the very least for the purposes of this blog and this blogging challenge. I may cover some things that are technically Cosmology related but whatever, it’s my blog I’ll do as I please.
Astronomy and astrology were associated at one point, and are often confused with each other, but astrology is not a science and is no longer recognized as having anything to do with astronomy. I will cover this distinction later in the month.
Astronomy is probably the oldest of the science. Humans have been looking up at the night sky and wondering about the moon, sun, and stars, and other plants, since forever. We’ve been charting the movements of the of these object and learning to navigate and tell time by the patterns we saw.
In fact, we have gotten very good at measuring and predicting the movements of the celestial objects we could see. Civilizations all over the world made significant discoveries and observations. The Babylonians started the scientific and mathematical and discovered that lunar eclipses followed a cycle. The ancient Greeks started by seeking rational, physical explanations for the movements and phenomena they observed. They measured distances and sizes of the sun and moon, they cataloged the starts and constellations. They could even predict the position of the Sun, Moon and planets for any given date.
That isn’t to say we haven’t made mistakes along the way, like thinking the the earth was flat, or thinking that we are at the center of the universe and assuming the heavens revolved around us. Galileo, my favorite astronomer, was even sentenced to life imprisonment in 1633 for defending the heliocentric model.
The thing I love about Astronomy is that it is one of the few science open to anyone and everyone who can afford to by a telescope or a pair of binoculars. Anyone can be an Astronomer and many of the discoveries made in the field were from amateurs. The most serious amateurs actively participate in the study of variable stars and the discovery of new asteroids or comets.
A while a lot of the science behind the movements can be hard to follow if physics and math isn’t your thing, but no one can deny the beauty of the universe or the excitement of the NASA’s missions. No one can say the they haven’t ever looked up at the sky and wondered, “what’s up there?”. That wonder, that awe, you feel when you see those starts, that is part of what it means to be human. That is something only we, as a species, can share across continents, and across time.
Image: The Andromeda Galaxy is a spiral galaxy approximately 2.5 million light-years away in the constellation Andromeda.
The Andromeda Galaxy is the nearest major galaxy to the Milky Way, but not the nearest galaxy overall. It gets its name from the area of the sky in which it appears, the constellation of Andromeda, which was named after the mythological princess Andromeda. The Andromeda Galaxy is the largest galaxy of the Local Group, which also contains the Milky Way, the Triangulum Galaxy, and about 44 other smaller galaxies.
The Andromeda Galaxy is the most massive galaxy in the Local Group as well. Despite earlier findings that suggested that the Milky Way contains more dark matter and could be the most massive in the grouping,the 2006 observations by the Spitzer Space Telescope revealed that M31 contains one trillion (1012) stars: at least twice the number of stars in the Milky Way, which is estimated to be 200–400 billion.
The image also shows Messier Objects 32 and 110, as well as NGC 206 (a bright star cloud in the Andromeda Galaxy) and the star Nu Andromedae. This image was taken using a hydrogen-alpha filter. By Adam Evans [CC BY 2.0], via Wikimedia Commons