Tag: Astronomy

It’s a New Year!

Well we have passed the Solstice!

Each year I try and promote the fact that we are in a New Year.

This year’s December Solstice took place at the moment this post was published: 20:19 PST .

Or in the words of EarthSky.org:

ooOOoo

All you need to know: December solstice

Posted by in | December 15, 2019

December solstice 2019 arrives on December 22 at 4:19 UTC.

That’s December 21 for much of North America. High summer for the Southern Hemisphere. For the Northern Hemisphere, the return of more sunlight!

Ian Hennes in Medicine Hat, Alberta, Canada, created this solargraph between a June solstice and a December solstice. It shows the path of the sun during that time period.

Late dawn. Early sunset. Short day. Long night. For us in the Northern Hemisphere, the December solstice marks the longest night and shortest day of the year. Meanwhile, on the day of the December solstice, the Southern Hemisphere has its longest day and shortest night. The 2019 December solstice takes place on Sunday, December 22, at 04:19 UTC (That’s December 21 at 10:19 p.m. CST; translate UTC to your time).

No matter where you live on Earth’s globe, a solstice is your signal to celebrate.

When is the solstice? The solstice happens at the same instant for all of us, everywhere on Earth. In 2019, the December solstice comes on December 21 at 10:19 p.m. CST. That’s on December 22 at 04:19 Universal Time (UTC). It’s when the sun on our sky’s dome reaches its farthest southward point for the year. At this solstice, the Northern Hemisphere has its shortest day and longest night of the year.

To find the time in your location, you have to translate to your time zone. Click here to translate Universal Time to your local time.

Just remember: you’re translating from 04:19 UT on December 22. For example, if you live in Perth, Australia, you need to add 8 hours to Universal Time to find out that the solstice happens on Sunday, December 22, at 12:19 p.m. AWST (Australian Western Standard Time).

Day and night sides of Earth at the instant of the December 2019 solstice (December 22, 2019, at 04:19 UTC). Image via EarthView.

What is a solstice? The earliest people on Earth knew that the sun’s path across the sky, the length of daylight, and the location of the sunrise and sunset all shifted in a regular way throughout the year. They built monuments such as Stonehenge in England – or, for example, at Machu Picchu in Peru – to follow the sun’s yearly progress.

But we today see the solstice differently. We can picture it from the vantage point of space. Today, we know that the solstice is an astronomical event, caused by Earth’s tilt on its axis and its motion in orbit around the sun.

Because Earth doesn’t orbit upright, but is instead tilted on its axis by 23 1/2 degrees, Earth’s Northern and Southern Hemispheres trade places in receiving the sun’s light and warmth most directly. The tilt of the Earth – not our distance from the sun – is what causes winter and summer. At the December solstice, the Northern Hemisphere is leaning most away from the sun for the year.

At the December solstice, Earth is positioned in its orbit so that the sun stays below the North Pole horizon. As seen from 23 1/2 degrees south of the equator, at the imaginary line encircling the globe known as the Tropic of Capricorn, the sun shines directly overhead at noon. This is as far south as the sun ever gets. All locations south of the equator have day lengths greater than 12 hours at the December solstice. Meanwhile, all locations north of the equator have day lengths less than 12 hours.

For us on the northern part of Earth, the shortest day comes at the solstice. After the winter solstice, the days get longer, and the nights shorter. It’s a seasonal shift that nearly everyone notices.

Earth has seasons because our world is tilted on its axis with respect to our orbit around the sun. Image via NASA.

Where should I look to see signs of the solstice in nature? Everywhere.

For all of Earth’s creatures, nothing is so fundamental as the length of daylight. After all, the sun is the ultimate source of all light and warmth on Earth.

If you live in the Northern Hemisphere, you can notice the late dawns and early sunsets, and the low arc of the sun across the sky each day. You might notice how low the sun appears in the sky at local noon. And be sure to look at your noontime shadow. Around the time of the December solstice, it’s your longest noontime shadow of the year.

In the Southern Hemisphere, it’s opposite. Dawn comes early, and dusk comes late. The sun is high. It’s your shortest noontime shadow of the year.

Around the time of the winter solstice, watch for late dawns, early sunsets, and the low arc of the sun across the sky each day. Notice your noontime shadow, the longest of the year. Photo via Serge Arsenie on Flickr.
Meanwhile, at the summer solstice, noontime shadows are short. Photo via the Slam Summer Beach Volleyball festival in Australia.

Why doesn’t the earliest sunset come on the shortest day? The December solstice marks the shortest day of the year in the Northern Hemisphere and longest day in the Southern Hemisphere. But the earliest sunset – or earliest sunrise if you’re south of the equator – happens before the December solstice. Many people notice this, and ask about it.

The key to understanding the earliest sunset is not to focus on the time of sunset or sunrise. The key is to focus on what is called true solar noon – the time of day that the sun reaches its highest point in its journey across your sky.

In early December, true solar noon comes nearly 10 minutes earlier by the clock than it does at the solstice around December 22. With true noon coming later on the solstice, so will the sunrise and sunset times.

It’s this discrepancy between clock time and sun time that causes the Northern Hemisphere’s earliest sunset and the Southern Hemisphere’s earliest sunrise to precede the December solstice.

The discrepancy occurs primarily because of the tilt of the Earth’s axis. A secondary but another contributing factor to this discrepancy between clock noon and sun noon comes from the Earth’s elliptical – oblong – orbit around the sun. The Earth’s orbit is not a perfect circle, and when we’re closest to the sun, our world moves fastest in orbit. Our closest point to the sun – or perihelion – comes in early January. So we are moving fastest in orbit around now, slightly faster than our average speed of about 18.5 miles per second (30 kilometers per second). The discrepancy between sun time and clock time is greater around the December solstice than the June solstice because we’re nearer the sun at this time of year.

Solstice sunsets, showing the sun’s position on the local horizon at December 2015 (left) and June 2016 (right) solstices from Mutare, Zimbabwe, via Peter Lowenstein.

The precise date of the earliest sunset depends on your latitude. At mid-northern latitudes, it comes in early December each year. At northern temperate latitudes farther north – such as in Canada and Alaska – the year’s earliest sunset comes around mid-December. Close to the Arctic Circle, the earliest sunset and the December solstice occur on or near the same day.

By the way, the latest sunrise doesn’t come on the solstice either. From mid-northern latitudes, the latest sunrise comes in early January.

The exact dates vary, but the sequence is always the same: earliest sunset in early December, shortest day on the solstice around December 22, latest sunrise in early January.

And so the cycle continues.

Solstice Pyrotechnics II by groovehouse on Flickr.

Bottom line: The 2019 December solstice takes place on Sunday, December 22, at 04:19 UTC (that’s December 21 at 10:19 p.m. CST; translate UTC to your time). It marks the Northern Hemisphere’s shortest day (first day of winter) and Southern Hemisphere’s longest day (first day of summer). Happy solstice, everyone!

ooOOoo

Well for many in the Northern Hemisphere the worst of the winter weather is yet to come.

But at least the days are drawing longer.

Welcome to the start of a New Year!

Carl Sagan

How very precious, vulnerable and fragile is this precious place we call home.

Today’s consciousness perambulation is the fault of Mr. P., as I like to call him. I refer to Pendantry as he is on his blog, Wibble.

You see on Sunday he added a comment to my post Just a small, white dot! that included the beautiful and awe-inspiring film made by the late Carl Sagan called Pale Blue Dot.

carl-sagan

Like millions of others, I came to admire Carl Sagan through watching the fabulous, the truly fabulous, television series Cosmos: A Personal Voyage. (NB. All the episodes are on YouTube, Episode One is at the end of this Post, Ed.)  Here’s how WikiPedia opens their reference to Carl.

Carl Edward Sagan (November 9, 1934 – December 20, 1996) was an American astronomer, astrophysicist, cosmologist, author, science popularizer and science communicator in astronomy and natural sciences. He spent most of his career as a professor of astronomy at Cornell University where he directed the Laboratory for Planetary Studies.

He published more than 600 scientific papers and articles and was author, co-author or editor of more than 20 books. He advocated scientifically skeptical inquiry and the scientific method, pioneered exobiology and promoted the Search for Extra-Terrestrial Intelligence (SETI).

Sagan is known for his popular science books and for the award-winning 1980 television series Cosmos: A Personal Voyage, which he narrated and co-wrote.  The book Cosmos was published to accompany the series. Sagan wrote the novel Contact, the basis for a 1997 film of the same name.

He died far too young and was a tragic loss to humanity.  The Carl Sagan web portal is here.

That 3:30 minute video Pale Blue Dot has, likewise, been seen by millions.  If you or someone you know hasn’t seen it, then you must pause now …

It’s practically impossible to watch that video and not embrace the central message from Mr. Sagan.  Here’s the transcript:

Our home from 6 billion kilometres. A very tiny dot against the vastness of space.

From this distant vantage point, the Earth might not seem of any particular interest. But for us, it’s different.

Consider again that dot. That’s here. That’s home. That’s us.

On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives.

The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilization, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every “superstar,” every “supreme leader,” every saint and sinner in the history of our species lived there – on a mote of dust suspended in a sunbeam.

The Earth is a very small stage in a vast cosmic arena.

Think of the rivers of blood spilled by all those generals and emperors so that in glory and triumph they could become the momentary masters of a fraction of a dot.

Think of the endless cruelties visited by the inhabitants of one corner of this pixel on the scarcely distinguishable inhabitants of some other corner. How frequent their misunderstandings, how eager they are to kill one another, how fervent their hatreds.

Our posturings, our imagined self-importance, the delusion that we have some privileged position in the universe, are challenged by this point of pale light. Our planet is a lonely speck in the great enveloping cosmic dark. In our obscurity – in all this vastness – there is no hint that help will come from elsewhere to save us from ourselves.

The Earth is the only world known, so far, to harbor life. There is nowhere else, at least in the near future, to which our species could migrate. Visit, yes. Settle, not yet. Like it or not, for the moment, the Earth is where we make our stand.

It has been said that astronomy is a humbling and character-building experience. There is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world. To me, it underscores our responsibility to deal more kindly with one another and to preserve and cherish the pale blue dot, the only home we’ve ever known.

Tomorrow, I will stay with the theme of our beautiful planet. Hope you can join me.

Now spoil yourself and watch Episode One of Cosmos.

The last 484 feet!

Some milestones on the age of the solar system.

Forgive me, dear readers, but something light and simple for today.  I don’t mean in the sense of the content, far from it, just easy for me to put the post together as it is from a presentation that I gave a year ago.

Here’s a picture of our solar system.

Most of us are reasonably familiar with this visual concept of our solar system, but what of it’s age?  That’s much more difficult to embrace in a way that we can relate to.

So let’s use something to represent the age of our solar system, the distance from Phoenix to Payson.

In round terms, Payson is 80 miles North-East from Phoenix.  Put another way, that’s 422,400 feet!

So if those 80 miles represented the age of our solar system, what would be the significant milestones on this metaphorical journey?

Phoenix represents the start, the ‘start’ of our solar system some 4.54 billion years ago

It was 1,075,000,000 years before Blue-green algae appeared.  That is the equivalent of travelling 18.94 miles from Phoenix North-East along Highway 87.  Or looking back, those algae appeared some 3.465 billion years ago.

But on we travel, metaphorically an unimaginable 3,459,800,000 years after the arrival of Blue-green algae until the next milestone; the earliest hominids.  In terms of our Highway that’s a further 60.97 miles.  Again, looking back that was 5,200,000 years ago.

The sharp-eyed among you will see that 18.94 miles added to 60.97 miles is 79.91 miles.  Goodness that’s awfully close to the total distance of 80 miles between Phoenix and Payson!  In fact, the 0.09 miles to run is the equivalent of 484 feet!

So let’s look at those last 484 feet.

The first 465.20 feet represents the approximately 5 million years after the earliest hominids appeared before H. sapiens arrived, some 200,000 years ago.

The appearance of Homo sapiens brings us to just 18.6 feet from Payson.

But first, we travel 9.3 feet and see the arrival of dogs, generally regarded to have separated, in DNA terms, from the Grey Wolf 100,000 years ago.

And are you 60 years old?  You were born just 0.0669 inches or 7/100ths of an inch from Payson!  If my maths is correct (someone please check!) 0.0669 inches is about 34 times the thickness of the human hair!  That’s very close to Payson!

Don’t know about you but it puts the age of our solar system into a perspective one might be able to get one’s arms around.

On the scale used above, one inch represents 895.68 years, one foot the equivalent of 10,748.11 years and a mile represents 56,750,000 years.

Anybody want to hazard a guess as to the state of our planet in one further inch?

The difference an inch makes! 895.68 years!

OK, let me stay more or less on topic and just round things off.

EarthSky website seems to have some great items, including this one.

Ten things you may not know about the solar system

9 ) Pluto is smaller than the USA
The greatest distance across the contiguous United States is nearly 2,900 miles (from Northern California to Maine). By the best current estimates, Pluto is just over 1400 miles across, less than half the width of the U.S. Certainly in size it is much smaller than any major planet, perhaps making it a bit easier to understand why a few years ago it was “demoted” from full planet status. It is now known as a “dwarf planet.”

Go here for the full list of ten items.

Finally, just how far does it all go?

How far do the stars stretch out into space? And what’s beyond them? In modern times, we built giant telescopes that have allowed us to cast our gaze deep into the universe. Astronomers have been able to look back to near the time of its birth. They’ve reconstructed the course of cosmic history in astonishing detail.

From intensive computer modeling, and myriad close observations, they’ve uncovered important clues to its ongoing evolution. Many now conclude that what we can see, the stars and galaxies that stretch out to the limits of our vision, represent only a small fraction of all there is.

Does the universe go on forever? Where do we fit within it? And how would the great thinkers have wrapped their brains around the far-out ideas on today’s cutting edge?

For those who find infinity hard to grasp, even troubling, you’re not alone. It’s a concept that has long tormented even the best minds.

Over two thousand years ago, the Greek mathematician Pythagoras and his followers saw numerical relationships as the key to understanding the world around them.

But in their investigation of geometric shapes, they discovered that some important ratios could not be expressed in simple numbers.

Take the circumference of a circle to its diameter, called Pi.

Computer scientists recently calculated Pi to 5 trillion digits, confirming what the Greeks learned: there are no repeating patterns and no ending in sight.

The discovery of the so-called irrational numbers like Pi was so disturbing, legend has it, that one member of the Pythagorian cult, Hippassus, was drowned at sea for divulging their existence.

A century later, the philosopher Zeno brought infinity into the open with a series of paradoxes: situations that are true, but strongly counter-intuitive.

In this modern update of one of Zeno’s paradoxes, say you have arrived at an intersection. But you are only allowed to cross the street in increments of half the distance to the other side. So to cross this finite distance, you must take an infinite number of steps.

In math today, it’s a given that you can subdivide any length an infinite number of times, or find an infinity of points along a line.

What made the idea of infinity so troubling to the Greeks is that it clashed with their goal of using numbers to explain the workings of the real world.

To the philosopher Aristotle, a century after Zeno, infinity evoked the formless chaos from which the world was thought to have emerged: a primordial state with no natural laws or limits, devoid of all form and content.

But if the universe is finite, what would happen if a warrior traveled to the edge and tossed a spear? Where would it go?

It would not fly off on an infinite journey, Aristotle said. Rather, it would join the motion of the stars in a crystalline sphere that encircled the Earth. To preserve the idea of a limited universe, Aristotle would craft an historic distinction.

On the one hand, Aristotle pointed to the irrational numbers such as Pi. Each new calculation results in an additional digit, but the final, final number in the string can never be specified. So Aristotle called it “potentially” infinite.

Then there’s the “actually infinite,” like the total number of points or subdivisions along a line. It’s literally uncountable. Aristotle reserved the status of “actually infinite” for the so-called “prime mover” that created the world and is beyond our capacity to understand. This became the basis for what’s called the Cosmological, or First Cause, argument for the existence of God.

Think I need to lie down now!

All in the meaning, postscript!

Life is without meaning. You bring the meaning to it.

The meaning of life is whatever you ascribe it to be.

Being alive is the meaning.

On the 28th March I wrote what I thought was a concluding piece on the subject of ‘meaning’.  I used some of the most amazing details about the universe to highlight the fact that, in the end, if our civilisation doesn’t get it’s collective act together then from the perspective of the universe it is all pretty irrelevant.  In that piece I quoted from Prof. Brian Cox, “Everything we are, everything that’s ever been and everything that will ever be was all forged in the same moment of creation 13.7bn years ago from an unimaginably hot and dense volume of matter less than the size of an atom.

Now, in fairness, Prof. Cox did allude to scientists exploring the notion of what might have happened before the Big Bang.  Anyway, a couple of nights ago we watched a BBC Horizon programme, now on YouTube, that looked much more closely into this fascinating topic.  The link came to us from the website Top Documentary Films that set out the introduction to the BBC programme.

They are the biggest questions that science can possibly ask: where did everything in our universe come from? How did it all begin? For nearly a hundred years, we thought we had the answer: a big bang some 14 billion years ago.

But now some scientists believe that was not really the beginning. Our universe may have had a life before this violent moment of creation.

Horizon takes the ultimate trip into the unknown, to explore a dizzying world of cosmic bounces, rips and multiple universes, and finds out what happened before the big bang.

Neil Turok, Director of Perimeter Institute for Theoretical Physics in Canada, working with Paul Steinhardt at Princeton, has proposed a radical new answer to cosmology’s deepest question: What banged?

Answer: Instead of the universe inexplicably springing into existence from a mysteriousinitial singularity, the Big Bang was a collision between two universes like ours existing as parallel membranes floating in a higher-dimensional space that we’re not aware of.

One bang is followed by another, in a potentially endless series of cosmic cycles, each one spelling the end of a universe and the beginning of a new one. Not one bang, but many.

Sir Roger Penrose has changed his mind about the Big Bang. He now imagines an eternal cycle of expanding universes where matter becomes energy and back again in the birth of new universes and so on and so on.

Here’s that programme.  Enjoy!

Harvest moon

There’s always much more to people than meets the eye!

I can’t recall at what point in the life of Learning from Dogs that Per Kurowski popped up over the parapet but it was pretty early on.  Per has been a great supporter of my varied efforts to promote the way that dogs are a wonderful example of integrity, trust and openness.

Anyway, Per comes from a background that one might not associate with the rest of this article.  Per used to be a director at the World Bank.  One of his Blogs includes this:

I warned many about the coming crisis, long before it happened, on many occasions and in many places, even at the World Bank. They did not want to listen and that´s ok, it usually happens, but what is not ok, is that they still do not seem to want to hear it. “We can easily forgive a child who is afraid of the dark; the real tragedy of life is when men are afraid of the light.” (Plato: 427 BC – 347 BC)

Just a couple of days ago, I posted about the moon that passed closer to the Earth on the 19th than for the last 20 years.  Per added a comment to that Post, “And this is a homemade version of the beautiful Harvest Moon song by Neil Young” With this link.  At that link you can watch and listen to Per singing ‘Harvest Moon’ recorded by Neil Young.  Enjoy.

Here was that moon, as seen from Payson in Arizona with some cloud in the sky!

 

That moon!

 

Finally, for those interested in the lyrics, here they are.

Come a little bit closer
Hear what I have to say
Just like children sleepin’
We could dream this night away.

But there’s a full moon risin’
Let’s go dancin’ in the light
We know where the music’s playin’
Let’s go out and feel the night.

Because I’m still in love with you
I want to see you dance again
Because I’m still in love with you
On this harvest moon.

When we were strangers
I watched you from afar
When we were lovers
I loved you with all my heart.

But now it’s gettin’ late
And the moon is climbin’ high
I want to celebrate
See it shinin’ in your eye.

Because I’m still in love with you
I want to see you dance again
Because I’m still in love with you
On this harvest moon.
Come a little bit closer
Hear what I have to say
Just like children sleepin’
We could dream this night away

But there’s a full moon risin’
Let’s go dancin’ in the light
We know where the music’s playin’
Let’s go out and feel the night

Because I’m still in love with you
I want to see you dance again
Because I’m still in love with you
On this harvest moon

When we were strangers
I watched you from afar
When we were lovers
I loved you with all my heart

But now it’s gettin’ late
And the moon is climbin’ high
I want to celebrate
See it shinin’ in your eye

Because I’m still in love with you
I want to see you dance again
Because I’m still in love with you
On this harvest moon