So, you think you’re slow? Not exactly…
Earth is rotating at its axis at about 1,070 mph.
Earth is orbiting around the sun at 66,600 mph.
Our Solar System, where the sun is the center, is orbiting the center of the Milky Way galaxy at around 559,234 mph.
The Milky Way is moving, relative to local group of galaxies, at around 671,080 mph.
The Universe is also expanding at ridiculous speed, which approximately about 46.2 miles per second per mega-parsec. A mega-parsec is roughly 3 million light years, which can’t be translated directly to mph or kph. Scientific American has a great article explaining about the speed of universe expansion in their website.
Here’s a quote by Phil Plait in his article (The Universe is still expanding):
Over the decades, that rate of expansion – called the Hubble Constant – has been measured many different ways. Using Cepheid variables is still a foundation of the work, though, and a new study just released by astronomers using the Spitzer Space Telescope show that the rate of expansion is 74.3 +/- 2.1 kilometers per second per megaparsec. What this means is that a galaxy one megaparsec away (that is, 3.26 million light years) will be moving away from us at 74.3 km/sec. If you double the distance to 2 megaparsecs, a galaxy would be moving away at twice that speed, or 148.6 km/sec.
Image courtesy of NASA.
Have you ever wondering where the name of the days comes from? Why there are 7 days in a week? Why not 10 so it’s easier to count because almost all of our calculation is using decimal system or 10-based numbers?
“It’s a warm summer evening in ancient Greece…”, said Sheldon Cooper. You know the super genius Sheldon from The Big Bang Theory. You’ll laugh when you know what I’m taking about! But if you don’t, check this IMDB site, and start watching!
Anyway, every ancient civilization has their cosmic stories about stars, gods and goddesses, the universe and the creation of the human world. Back then, there were no enough light sources like what we have now. At night, the only sources of light were bonfire or maybe none at all. The sky was literary full of stars and all of the glorious things that the could be seen with the naked eyes. Bright and clear! Some of them became obsessed and started learning the sky object’s behavior in reference to the earth. It is really impressive to see the documents (not literary) painted on the cave walls, long tunnels inside the pyramid, coffins, tree barks or other mediums. Here is an example of the discovery:
In 185 CE, Chinese astronomers recorded the appearance of a bright star in the sky, and observed that it took about eight months to fade from the sky. It was observed to sparkle like a star and did not move across the heavens like a comet. These observations are consistent with the appearance of a supernova, and this is believed to be the oldest confirmed record of a supernova event by humankind. SN 185 may have also possibly been recorded in Roman literature, though no records have survived. – Source: Wikipedia
In the old days, people still believed that earth was the center of the universe. Ancient astronomers started creating their own heaven maps in conjunction to their location. After long observation, the sky maps became one of the civilization’s treasures because they could tell when the season starts, what to plant and when to start harvesting. That was the starting point of almanac and astrology which we know today. Almanac is predicting season and regional weather based on the stars position, where on other hand astrology is predicting someone’s life. The first one is considered to be accurate because of the cycle of the universe is pretty much the same from year to year, but the second one is more the pseudo-science which has no relation to the stars at all. Buy hey, it’s another topic of discussion and let’s not go there.
Once the ancient astronomers became the sky expert, they started noticing that some “stars” are more dynamic, active and exotic than others. Those “stars” are exclusive and so special! The ancient Greek calls them “the wanderers” or planetes (πλανήτης). Aha! That’s where the word planet originated from.
According to Greek, those planets are the sun and the moon, and five (5) special objects which are visible without using telescope or other tools. They are Mercury, Venus, Mars, Jupiter and Saturn. I think this one deserves another “aha” moment? Or eureka maybe? Anyway, the 7 majestic objects in the sky became natural wonders for the ancient civilization. Thus, it wouldn’t be a surprise at all to see when people started promoting them to represent the super-beings who take control the universe. In fact, those planets are in the sky, out of human reach physically and philosophically. The term of super-being is absolutely perfect, isn’t it? Each object is declared as god or goddess, and each day is dedicated to one super-being. Now you know that there are 7 days in a week! However, not all ancient civilizations have 7 gods or goddesses. Since the planet story (7 classical planets) were originated from ancient Greek and Roman civilization, it had a higher chance to reach a wider area during military events and trading routes compare to others.
What about name? This took hundred years to evolve. Let’s start with Greek first. Based on their observation, the days were sorted by the closest distance from the planet earth. Remember, in that time, they believed that earth was the center of the universe. So, the order was Moon, Mercury, Venus, Sun, Mars, Jupiter and Saturn. Well, not exactly accurate, but it was believed that way in that time.
When the Roman Empire spread around the region, there are many tradition transitions, from the original Greco-Roman to Gaelic-Irish and finally Germanic. The name of the day started mixing up and evolved to the base word of today’s name. There’s no accurate documentation when exactly the naming started, but historian predicted it was between 400AD and 7-8th century. Let’s take a look:
- Sunday: Sunnandæg meaning “Sun’s day”
- Monday: Mōnandæg meaning “Moon’s day”
- Tuesday: Tīwesdæg meaning “Tiw’s day, a one-handed god associated with single combat. The name is based on Latin dies Martis, “Day of Mars”.
- Wednesday: Wōdnesdæg meaning the day of the Germanic god Wodan. It is based on Latin dies Mercurii, “Day of Mercury.”
- Thursday: Þūnresdæg meaning ‘Þunor’s day’, thunder or its personification, the Norse god known in Modern English as Thor. Thor’s day corresponds to Latin dies Iovis or “Day of Jupiter”.
- Friday: Frīgedæg meaning the day of the Norse goddess Fríge. It is based on the Latin dies Veneris, “Day of Venus.”
- Saturday: Sæturnesdæg. In Latin it was dies Saturni, “Day of Saturn.”
That’s all for now. Hope you enjoy it