July 21, 2017--The Universe

I've been reading Marcia Bartusiak's excellent The Day We Found the Universe, which is largely about how astronomers came to measure the size of our solar system, the galaxy of which our sun and the earth are a part, and ultimately the expanse of the entire universe.

Many astronomers contributed to what we now know about these cosmic distances. But Edwin Hubble is featured in the book as he is the astronomer who subjected all the partial theories to scrutiny and incorporated those that contributed to his own research about the size and components of the expanding universe.

He, thus, is thought to be the most important of cosmologists, the discoverer of the universe.

The book is primarily about sizes and distances. Less about motion and stellar velocities. But I have also been thinking about the speed of galactic bodies. For example, to complete one daily, 24-hour cycle how fast is the earth rotating? It turns out to be nearly 1,000 miles per hour.

Then there are other related, mind-boggling things to think about. For example, how fast is the earth moving as it completes its 365-day orbit around the sun? It turns out to be an astonishing 66,000 mph.

Earth along with the other planets and the sun that make up our solar system are also in motion.

That system is part of a vast galaxy, the Milky Way, and it circumnavigates that galaxy at 44,000 mph.

Also, the entire galaxy itself is in motion--it rotates-- and the earth, as part of the galaxy, rotates along with it as it, over 225 million years, completes one full rotation (a galactic year). The speed of rotation is an incomprehensible 483,000 miles per hour.

And finally, the galaxy itself is moving through space at 1.3 million mph.

To summarize these five interconnected movements--

• 1,000 miles per hour is the speed of the earth's rotation;
• 66,000 mph is how fast the earth goes about its 365-days-a-year orbit of the sun;
• 44,000 miles per hour is how fast our sun and planets (our solar system) whips along as it circles the Milky Way galaxy;
• 483,000 mph is how fast the Milky Way is racing to complete its 225-million-year circuit;
• And 1.3 million miles per hour is the speed at which our galaxy moves through the universe.

It is a wonder that we aren't tossed off into space as the result of the sum of these five velocities.

The why of that is a whole other conversation.

Words, especially superlatives, fail me.