Author Tim Harford, who wrote The Logic of Life and a few other books I've liked, yesterday published an explanation of what telling time is all about:
Water clocks appear in civilisations from ancient Egypt to medieval Persia. Others kept time from marks on candles. But even the most accurate devices might wander by 15 minutes a day. This didn't matter to a monk wanting to know when to pray.
But there was one increasingly important area of life where the inability to keep accurate time was of huge economic significance: sailing.
By observing the angle of the Sun, sailors could calculate their latitude - where they were from north to south. But their longitude - where they were from east to west - had to be guessed.
Mistakes could - and frequently did - lead to ships hitting land hundreds of miles away from where navigators thought they were, sometimes disastrously.
How could accurate timekeeping help? If you knew when it was midday at Greenwich Observatory - or any other reference point - you could observe the Sun, calculate the time difference, and work out the distance.
But does anybody really know what time it is?
Sigh:
I hope to read these articles sometime this year.
Not exactly a slow news day:
- Former Alabama Senator Jeff Sessions won confirmation as Attorney General of the U.S. on a 52-47 party-line vote.
- Meanwhile, the Senate told Massachusetts Senator Elizabeth Warren to sit down and shut up, but "she persisted," thus beginning her 2020 presidential campaign.
- And though the event was almost 26 full hours ago, yesterday's appeals court hearing in California resulted in a Trump tweet being rebuked by the President's own nominee for the Supreme Court. (The BBC has a really good primer on the U.S. constitutional system of checks and balances, for those overseas.)
- Speaking of the president, it's becoming clear as day that his motivations are very simple, and amount to a total integration of his businesses with the office. Just like we told you.
- Also, we should expect more crises, real and imagined, to scare people into supporting his consolidation of power.
- Closer to home, the building I work in, Willis Tower, has secured a $1bn refinancing that will free up funds for a $500m upgrade. Too bad the company that built it will be dead within two years, according to the bond markets.
And finally, for those of you living in the new, evidence-free world of today, you'll be happy to know that all of these things may have come about because of the lunar eclipse and comet happening Friday night.
Stuff I'll read before rehearsal today:
Back to the mines...
January 3rd is one of my favorite days of the year in astronomy, because it's the day that the northern hemisphere has its latest sunrise of the winter. This morning in Chicago, the sun rose at 7:19 (though it rose behind a thick rainy overcast), just a few seconds later than it rose yesterday. But tomorrow it will rise just a few seconds earlier, then a few more, until by the end of January it'll rise more than a minute earlier each day.
Meanwhile, thanks to the eccentricity of our orbit around the sun, sunsets have gotten later since the first week of December. It's noticeable now; today's sunset at 16:33 is 14 minutes later than the earliest sunset on December 7th. A week from now sunset is at 16:40; a week later, at 16:48.
By January 31st we will see more clearly that the dark days of northern hemisphere winter are ending. Sunrise at 7:04 and sunset at 17:04 gives us 10 full hours of sunlight, 47 minutes more than we'll get today.
So even though the 115th Congress opened today in Washington, with the House Republicans proposing to geld their own ethics watchdog (and why would they want to do that, hmmm?), at least things will literally get more sunny throughout the country every day for the next six months.
The 2017 Chicago sunrise chart is now available. Share and enjoy.
For those of us in the northern hemisphere in places that observe daylight savings time on U.S. rules—that is, for most of the U.S. and Canada—this morning's sunrise was (or will be, west of the Rockies) the latest sunrise until 6 November 2027.
I've got to say, the sun rising around 7:30 has not helped my mornings. Tonight we return to standard time, putting tomorrow's sunrise at 6:30, and making it easier to get out of bed Monday morning.
Of course, from Decmeber 1st to February 4th, the sun will rise after 7 here in Chicago. And by this time next week we'll have less than 10 hours of daylight.
At least I'm not in places along the western edge of a time zone, like Lafayette Landing, Mich., where the sun didn't rise until 8:48 local time this morning. I'd bet they've been ready for a change for weeks now.
The Chicago sunrise chart for 2016-17 is up, just a few weeks late. (Look, I've been busy.)
In the last 40 years, astronomers have gathered more and more evidence that our moon came out of a scarcely-imaginable collision between a baby (100-million-year-old) Earth and another proto-planet named Theia. (Watch this video for a good explanation.) Just two weeks ago, astronomers at UCLA announced a clarification: Theia didn't hit Earth in a glancing blow, as previously thought. Instead, the two planets hit head-on:
“We don’t see any difference between the Earth’s and the moon’s oxygen isotopes; they’re indistinguishable,” said Edward Young, lead author of the new study and a UCLA professor of geochemistry and cosmochemistry.
The fact that oxygen in rocks on the Earth and our moon share chemical signatures was very telling, Young said. Had Earth and Theia collided in a glancing side blow, the vast majority of the moon would have been made mainly of Theia, and the Earth and moon should have different oxygen isotopes. A head-on collision, however, likely would have resulted in similar chemical composition of both Earth and the moon.
“Theia was thoroughly mixed into both the Earth and the moon, and evenly dispersed between them,” Young said. “This explains why we don’t see a different signature of Theia in the moon versus the Earth.”
So why am I reviewing catastrophic astronomical events? I'm reading Neal Stephenson's latest novel, Seveneaves, which posits (in its opening paragraph) the collision between our moon and what is probably a small black hole. Stephenson imagines what would happen from a serious, scientific perspective.
Seveneves isn't what you would call a character piece. I'm 45% through it, according to my Kindle, and thoroughly fascinated. But Stephenson is almost the anti-Ishiguro.
Another aside: I have to see the tidal bore in the Bay of Fundy someday. It just sounds so cool—especially in context.
This means I have some time to digest this over the weekend:
I might have a chance to read this weekend. Perhaps.