Archive for the ‘The Sun’ Category
Here in the United States, we’ve pulled the plug on Daylight Savings Time. Oh, we’ll get it back come March, but for now, we’re darkening the evenings and lighting up the mornings just a tad. Some of us head off to work in darkness and come home when the lights come on. There seems to be something wrong with lights out at 4:30 in the afternoon. Sunlight, that is.
There are plenty of stories and studies about how harmful this rearranging of the clock can be. Circadian rhythms lose their beat. People become grouchy from the loss of an hour. Productivity slacks off at work. Accidents increase. And so on. Can’t argue with it, really. Losing that hour’s sleep in spring means I’ll have one less hour to hide under the covers and face reality. But then again, it’s so wonderful to have that extra hour once a year. It’s almost a free invitation to sleep in or stay out a bit longer than you normally would’ve.
We’ve tinkered with the time since DST was enacted in this country in 1918, just over 100 years ago. During World War II we had it year-round to make better use of sunlight. In 1975 DST was enacted in January. I remember that because I was a school kid catching the bus in the dark. Weird. And recently we’ve expanded DST to begin the last weekend in March and end the first weekend in November.
As for me, I enjoy the longer summer days. That sun comes up plenty early for me at 5:30 am and sticks around until 8:30 – in New York. Some parts of the US get even more. If the sun came up at 4:30 and set at 7:30, without DST, I’d feel cheated somehow. The last thing I want to do is get up that early and not be able to enjoy the pleasant rays of light hone I come home from work. Of course, there are plenty of people, like farmers and early shift workers who’d enjoy the sun rising that early.
The sun’s rays reach us for longer periods of time because the the tilt of the earth’s axis. It’s just the way our planet is positioned as it travels around the sun. But if one lives at the equator, days are fairly equal all year around. At the poles, it’s all or nothing.
It’s been deliberated that DST should end, but I can’t see that ever happening. Too many of us enjoy the long summer days, even if there’s the inconvenience of losing an hour’s sleep once a year. It might take a couple of days to adjust, but at least it happens over a weekend when most of us can sleep.
All I know is when DST goes back to Eastern Standard Time, I’m a little sad, because it means the nights are creeping closer and the daylight is drawing thin. Sunlight’s a precious gem, to be appreciated when it’s given, for when it’s gone, it’s dark out there, folks! But once December 21 hits, it’s all uphill from there.
In the meantime, appreciate the moon. It shines its highest and brightest in winter. There’s nothing so glorious as to see it glisten on the snow. Or lighten the nighttime skies in the Caribbean, where one might be taking a vacation to skip out on winter.
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Credits: Event Horizon Telescope collaboration et al.
So where does one begin on a day like today? I can’t honestly say what story could top seeing a photograph of an actual black hole. But the news certainly is fascinating. And check out the link. There’s a complete picture of Messier 87, a giant galaxy some 55 million light years away, located in Virgo.
Einstein theorized in a paper published in 1915 that star’s light rays curved around the sun during an eclipse. That meant the stars appeared about 1.75 second of arc away from their positions.
In May 29, 1919, when a six-minute total eclipse in Brazil caused British astronomer Arthur Eddington to determine that light rays from other stars bent when subjected to the gravitational field of our sun. He proved this through the use of photographs, and others have proven it since.
Jump to 2016. MIT graduate student Katie Bouman created the algorithm that produced the first image of the black hole. Her contributions seem to be a bit underreported, but thanks to her work, we now see the image pictured above.
Credit: Kennedy Space Center
The second big story (to me at least) is Falcon Heavy. It was supposed to launch today, but thanks to high winds aloft, we’re going to have to wait until tomorrow. But the cool thing about it is its three boosters, all expected to land perfectly. I’m always fascinated by this new generation of rockets. Elon Musk, for all his faults, is a genius. Not only did he create a better class of rockets, partly recyclable, he also made their capsules so sleekly modern.
And lastly, on April 11 NASA will host a teleconference on its study of its astronaut twins, Mark Kelly and Scott Kelly. This eagerly-awaited report will detail how Scott Kelly was affected by living in the ISS for 340 days, as compared to his twin brother, Mark Kelly, who remained on Earth. So far, these are the only twins who have both served on the ISS, and, as such, are uniquely qualified for this important study.
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How many of you look forward to gazing at the moon and witnessing one of Nature’s Greatest Wonders, such as the lunar eclipse pictured above? They happen twice a year, about two weeks apart from a solar eclipse. It’s the dance the moon and the sun do, shading the earth in a few places, and giving us a fabulous show.
But on August 18, something odd’s going to happen. The Sun, Moon and Earth will be closely aligned that day, but their shadows will not meet. It’s as if they’re all flirting with each other, yet don’t quite know whom to choose. So they hold off a bit.
Then, one month later, the Moon gets its chance with a Penumbral eclipse (also, not quite total, but almost), crossing two dates, on September 16 & 17. But here’s the thing with a Penumbral eclipse: you might not notice anything. In fact, most people see a normal full moon. A keen eye will notice it’s a bit darker, but only just. See, this kind of eclipse happens when the Moon passes through the faint part of the Earth’s outer shadow. The Sun, Moon and Earth are imperfectly aligned, so they can’t do what naturally should come to them – an eclipse – so they go through the motions and orbit away.
Sandwiched between those two almost lunar events is an Annular solar eclipse on September 1. That, too, is an almost-but-not-quite event, with the Moon standing a hair’s breadth too far from the Sun to block its light entirely, but enough to cast a pretty decent shadow and darkening things in its path. It’s kind of like going to the movies and someone with an enormous head sits directly in front of you. You can’t really make out the whole film, but at the screen’s edges you see a tidbit of the action. What a viewer will see is a “ring of fire” around the edges of the moon. The sky does darken and if you glance at the sun (eyes protected with a filter!), it’ll look pretty darn cool.
So look out, folks! Or you might miss something…
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Credit: NASA
There’s a whole lot going on in nature this week. Take, for example, the March 20th total eclipse. It’s the first total for a couple of years. The others have been annular, or the kind where the moon doesn’t quite hide the sun and it peeks out like a ring. And in case you didn’t know, eclipses come in pairs, two weeks apart: the sun hides its face, then the moon. It’s just the way nature works. Not everyone gets to see this spectacular event; those in the northern extremes of Europe (and polar regions) will see it just fine, but the rest of Europe will have to settle for a partial eclipse. That’s fine by me, something is better than nothing.
Eclipses are weird. I experienced a total eclipse when I was about 7 or 8 years old. It was covered live on TV, when people still held wonderment and what nature could do. I clearly remember it got dark, a fairly good representation of the stars came out, birds went silent and all became still. Mom admonished me for looking up at the sky, yet both of us snuck a peek and I remember getting a chill. It was so, so strange to see this blackness where the sun ought to be. Lots of our neighbors came outside and pointed and laughed nervously. We all knew better. We knew that the sun’d pop back out again and the warmth would return, birds would wake up, a bit confused at the short night, perhaps, but ready to launch into song once more. And sure enough, it did. Everyone retreated to the inside of their houses, catching the few last bits of the broadcast describing the marvel we all experienced.
So what if the sun got stuck, though, behind the moon? Suppose, just for an hour or two, the sun had had enough of working to warm the planet. The moon, normally a celestial object waiting to dominate the evening sky, chose not to budge, either. Let’s say they went to war. A line was drawn in the sky, and neither of them were giving way until the other relented. Imagine what people might say then? Oh, they’d be all right with it for about the first five or ten minutes, but after that? A nip in the air becomes a chill, then cold, then freeze. Our balance turns wobbly, then a sickly feeling emerges from our insides. Hair rises off of our heads as breezes end. Building creak, water flows everywhere and electricity shorts out. Planes can’t fly. Our world ceases, but still exists. The National Guard is called out, but is helpless against the force of nature.
Take that, Nature says, and keep on ruining the planet. I’ll take care of matters for myself. When all of you have had your fill of ignorance, I’ll imbue you with light. Until then, may the best people evolve, while I clean house.
Ah, if only…
In the meantime, we’re still here, facing the Ides of March, Pi Day, and the inevitable East Coast first day of spring snowstorm from the relentless winter we’ve been experiencing. Can’t wait to shovel that 3″ – 6″ in the driveway.
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Afternoon analemma photo taken in 1998-1999 by Jack Fishburn in Murray Hill, NJ. Bell Laboratories building in foreground
Have you ever noticed in the mornings, from about mid-December to around mid-January that the sun rises the same time every day? Even though the time of the setting sun changes, the dawn keeps breaking at 7:21 am (or whatever time your sun happens to rise, depending upon where in the world you live). It’s as if it’s stuck, needing an extra nudge to get it moving. Once again, from about mid-June to mid-July, the same thing happens with the sun once more.
As illustrated in the photo above, this phenomena is called an analemma. The Merriam-Webster dictionary defines it as, “a plot or graph of the position of the sun in the sky at a certain time of day (as noon) at one locale measured throughout the year that has the shape of a figure 8; also : a scale (as on a globe or sundial) based on such a plot that shows the sun’s position for each day of the year or that allows local mean time to be determined.”
So, if one were to take a picture of the sun at the same time every day, from exactly the same position, you’d more or less wind up with a figure 8. It’s proof that the Earth’s axis is tilted at 23.439°. However, the angle at which it’s seen changes wherever one is located on Earth. The above was taken at roughly 40° north. Here is a picture taken at Veszprem, Hungary, which is latitude 47°:
Image Credit & Copyright: Tamas Ladanyi – Analemma 2011 – taken at 9:00 am
So at 47°, the sun’s angle’s a bit sharper.
Here’s an excellent link from the Washington Post that illustrates how the sun moves in the sky through the months.
And who can forget the moon? Since it rises and sets, it too creates its own analemma. However, the moon rises 51 minutes later every day, so in order to successfully photograph it, one has to take that into account. Understanding that means the moon returns to the same position 51 minutes later, in accordance to its rising. Still, with patience, one can create an excellent example of what the moon can do, although one has to also remember it has phases. That creates a wonderful variety of shapes. Here’s an example:
Credit & Copyright: Rich Richins
Earth isn’t the only place where the analemma occurs. Any planet where the sun shines also shares this perspective, although it’s teardrop shaped on Mars:
Digital Illustration Credit & Copyright: Dennis Mammana (Skyscapes)
Why the different shape? Here’s the explanation from NASA:
“On planet Earth, an analemma is the figure-8 loop you get when you mark the position of the Sun at the same time each day throughout the year. But similarly marking the position of the Sun in the Martian sky would produce the simpler, stretched pear shape in this digital illustration, based on the Mars Pathfinder project’s famous Presidential Panorama view from the surface. The simulation shows the late afternoon Sun that would have been seen from the Sagan Memorial Station once every 30 Martian days (sols) beginning on Pathfinder’s Sol 24 (July 29, 1997). Slightly less bright, the simulated Sun is only about two thirds the size as seen from Earth, while the Martian dust, responsible for the reddish sky of Mars, also scatters some blue light around the solar disk.”
Each planet, given its north-south axis tilt and shape of its orbit, has its own analemma shape:
- Mercury – nearly straight line
- Venus – ellipse
- Mars – teardrop (as illustrated above)
- Jupiter – ellipse
- Saturn – figure 8, but with tight northern loop
- Uranus – figure 8
- Neptune – figure 8
Let me add that you don’t necessarily need a camera to record the sun’s analemma. Think back to the movie “Cast Away” wherein Tom Hanks marks on stone where the sun travels throughout the year. You can make note by just looking out the window and the same time each day, seeing where the sun happens to be at the same time each day. It’s pretty cool. Try it!
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Moon, Stars and Beyond 