21 January 2021

One of the puzzling laws of nature is that the basic units of light — photons — are both waves and particles and though they have no mass they exert pressure on the objects they hit. On Earth this pressure is so tiny that it goes unnoticed but in outer space it is the main force other than gravity and has a large cumulative effect over time. It is called radiation pressure or the force of light.

Spacecraft engineers design for radiation pressure because it affects how a spacecraft moves. For instance, when light is reflected off an object in outer space it picks up momentum from the force of light and moves away from it. This diagram shows the change in momentum where light (dark blue color) is reflected.

Just over seven years ago during the Move An Asteroid Competition MIT suggested using radiation pressure to protect Earth from dangerous asteroids. How? Paint the asteroids white to reflect more light. Check out the plan in this vintage article: Paintballs To The Rescue.

(images from Wikimedia Commons; click on the captions to see the originals)

18 January 2021

At the end of yesterday’s blog post about Panther Hollow and Four Mile Run I explained a local naming convention that’s a mystery to people from other parts of the country. The noun “run” means the act of running or a route taken on a regular basis yet in Pittsburgh it also means “creek.”

A stream is called a “Run” in Pennsylvania, northern West Virginia, eastern Ohio and western Maryland. Derek Watkins’ map of Generic Terms for Streams in the Contiguous U.S., generated from GNIS data, shows the places where people use different words for Creek including: Branch, fork, run, brook, kill, stream, bayou, swamp, slough, wash, cañada, arroyo, rio. (Click here to see his map.)

— from The Rise and Fall of Panther Hollow Lake by Kate St. John

Using the Geographic Names Information System (GNIS), Pfly generated a map of just two words — “Run” in red and “Branch” in blue. South of here, Branch and Run coexist then Branch takes over.

There are other anomalies as well. Hollow, as in Panther Hollow, is our name for a narrow valley. The term is used throughout Appalachia and in places where Appalachians settled later such as the Ozarks, Utah, Texas, and parts of Oregon and Wisconsin(*). Everywhere else out West a narrow valley is a Gulch. Since the West is dry we think gulches are dry, but they don’t have to be.

Here’s Pfly’s map of Hollow in orange versus Gulch in blue.

So a Run in a Hollow could be called a Branch in a Gulch.

Nine Mile Branch at Duck Gulch is pictured at top.

It just doesn’t sound right.

(photo by Kate St. John, maps by Pfly on Flickr, Creative Commons licensing)

p.s. (*) The Hollow vs Gulch map is interesting from a Western migration perspective showing places where Appalachians settled later. For instance,

• Utah was settled by Mormons from Upstate New York.
• Parts of Texas were settled by Appalachians looking for more land. For instance, my great-grandparents emigrated from Appalachian Tennessee to northeastern Texas near the town of Paris.
• Southwestern Wisconsin uses both Branch and Hollow, terms from the southern Appalachians. Derek Watkins speculates that this patch may have come from Appalachian in-migration “during a regional lead mining boom in the early 19th century.”

1 January 2021

2020 was an awful year and it will take a while before 2021 is any better, but no matter what’s happening there’s a way to take your mind off the mess and calm down: Get outdoors.

Lots of people took this advice and discovered birding in 2020. A new year, a new month, a new day is a great time to see more birds.

This week I rediscovered good resolutions for the New Year in an interview I gave on The Allegheny Front in the summer of 2009(*).

Go outdoors, look around, look up.  You’ll get a view of things that are bigger than yourself. … I find it very calming to see that life goes on despite whatever is going on in my head. Nature is still rolling.

— Allegheny Front radio interview with Kate St. John, 2009

So despite the tedium of putting on winter clothes, trudging in gray weather, and dealing with foggy glasses, make the effort. Get outdoors. Look up. There’s always something out there.

Hot tip: If you’re in the Pittsburgh area go see the evening grosbeaks at North Park (photos at this link). They’ve been at this location for several days including yesterday, 31 Dec 2020. Park at the north end of the Spillway Lot.

Notes on the interview(*) A lot has changed in 12 years. In the interview I said that I work at WQED (No. I retired in 2014), that my blog is on WQED’s website (No. It’s been at birdsoutsidemywindow.org since 2015), that I hike alone (No. Now that I’m retired and due to COVID restrictions, hiking/birding is my one opportunity to see friends). And I’m older now with a lot more wrinkles under that mask.

(photo by Donna Foyle, audio from The Allegheny Front, 2009)

19 December 2020

As we approach the shortest day(*) of the northern year we can take heart that our days are as long as they are. 70 million years ago, in the age of the dinosaurs, the Earth spun faster than it does today. Rather than having 86,400 seconds per day to get things done, dinosaur days were half an hour shorter.

This discovery came to light when paleontologists used lasers to study the growth rings of a rudist bivalve fossil found in the mountains of Oman. During the Cretaceous period rudist bivalves lived in tropical seas and grew throughout their lifetimes, laying down new shell material every day.

The lasers were precise enough to identify four to five data points within each day cycle and see that …

The composition of the shell changed more over the course of a day than over seasons, or with the cycles of ocean tides. The fine-scale resolution of the daily layers shows the shell grew much faster during the day than at night.

— AGU.org: Ancient shell shows days were half hour shorter 70 million years ago

Thus “the growth rings allowed the researchers to determine the number of days in a year and more accurately calculate the length of a day 70 million years ago.” They also discovered information on the Moon’s formation and proximity. — agu.org

The Earth, like all of us, is slowing down with age. Every day is infinitesimally longer than the last. (It sure has felt that way during the COVID-19 pandemic!) On the bright side, even when we feel rushed we can be glad we have that daily half hour the dinosaurs missed.

Read more at: Ancient shell shows days were half hour shorter 70 million years ago.

(illustration of dinosaurs from Wikimedia Commons; click on the caption to see the original)

(*) The winter solstice is at 5:02am ET on 21 December 2020.