In 2018,

• Earth picked up about 40,000 metric tons of interplanetary material, mostly dust, much of it from comets.
• Earth lost around 96,250 metric tons of hydrogen and helium, the lightest elements, which escaped to outer space.
• Roughly 505,000 cubic kilometers of water fell on Earth’s surface as rain, snow, or other types of precipitation.
• Bristlecone pines, which can live for millennia, each gained perhaps a hundredth of an inch in diameter.
• Countless mayflies came and went.
• More than one hundred thirty-six million people were born in 2018, and more than fifty-seven million died.
• Tidal interactions are very slowly increasing the distance between Earth and the moon, which ended 2018 about 3.8 centimeters further apart than they were at the beginning. As a consequence, Earth is now rotating slightly more slowly; the day is a tiny fraction of a second longer.
• Earth and the sun are also creeping apart, by around 1.5 centimeters per year. Most of the change is due to changes in the sun’s gravitational pull as it converts some of its mass into energy by nuclear fusion.
• The entire solar system traveled roughly 7.25 billion kilometers in its orbit about the center of the Milky Way. This vast distance, however, is only about 1/230,000,000th of the entire orbit.
• There were two lunar eclipses and three partial solar eclipses, each a step in the long gravitational dance making up the roughly 18-year saros cycle. During one saros cycle, eclipses with particular characteristics (partial, total, annular) and a specific Earth–Moon–Sun geometry occur in a predictable sequence; at the end, the whole thing starts again. This pattern has been repeating for much longer than humans have been around to see it.

I like knowing these bits of cosmic context because they link me to a larger world. I can echo the words of Ptolemy: “Mortal as I am, I know that I am born for a day. But when I follow at my pleasure the serried multitude of the stars in their circular course, my feet no longer touch the earth.”

~ Mary Hrovat, from “This Year on Earth” (3 Quarks Daily, December 24, 2018)

Don’t miss the rest of her essay here: This Year on Earth

Notes:

• Photo: Phys.org.
• Related Posts: Miracle. All of it.
• Inspiration: Inspired by Albert Einstein’s quote: “There are only two ways to live your life. One is as though nothing is a miracle. The other is as though everything is a miracle.”