Tag: Deborah Byrd

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!

Picture Parade Two Hundred and Ninety-Five

That Chilean eclipse!

From EarthSky:

More amazing images of the July 2 eclipse

Some called it the “astronomer’s eclipse” because it passed near major observatories in Chile. Check out these beautiful images of the July 2, 2019, total solar eclipse.

This composite image captures the drama of totality during the July 2, 2019, total solar eclipse. When – as seen from Earth – the moon passes directly in front of the sun, the sun’s light is blocked and its extended atmosphere or corona can be seen. The processing of this image highlights the intricate detail of the corona, its structures shaped by the sun’s magnetic field. Some details of the lunar surface can also be seen. The image – via European Space Agency (ESA) – was created by the ESA-CESAR team observing the eclipse from ESO’s La Silla Observatory in Chile, South America.
A prominence seen in the sun’s chromosphere during the July 2, 2019, total solar eclipse. Prominences are made of tangled magnetic field lines that keep dense concentrations of solar plasma suspended above the sun’s surface. They are anchored to the sun’s visible surface and extend outwards through the chromosphere and out into the corona. The red hue of the chromosphere is only apparent during an eclipse. This image – via ESA – was taken by the ESA-CESAR team observing the eclipse from ESO’s La Silla Observatory in Chile, South America.
View at EarthSky Community Photos. | Total solar eclipse over Vicuna, Chile, on July 2, 2019 from Alexander Krivenyshev of the website WorldTimeZone.com.
View at EarthSky Community Photos. | Pablo Goffard caught the July 2 total solar eclipse from Incahuasi, Chile. He wrote: “This is just a photo, a tiny part of the experience. Incahuasi is a small town in the Atacama desert. Here it’s seen the camp installed especially for the eclipse.”
This image of eclipse-watchers was taken by a frequent EarthSky contributor, Yuri Beletsky, on the Chilean coast. It was chosen as an Astronomy Picture of the Day for July 4, 2019. Congratulations on a wonderful photo, Yuri! Note that diffraction spikes (apparent rays from the sun) are effects from the camera lens aperture.

While some observers on the southern part of Earth saw a total solar eclipse, the European Space Agency’s PROBA-2satellite’s SWAP imager in space saw a partial eclipse, as shown in the video below. The images are in ultraviolet light, revealing the turbulent nature of the sun’s surface and corona. ESA said:

During this eclipse the satellite was passing through the South Atlantic Anomaly at the time of the largest occultation [covering of the sun]. In this region the spacecraft is exposed to higher levels of radiation. The increased flux of energetic particles falling on the satellite’s detector is the cause for all the bright dots and streaks in the images.

Bottom line: More amazing images of the July 2, 2019, total solar eclipse.

There is more, much more, on the Smithsonian magazine website. Do go across and see the images.

We are of the stars!

I so relate to this item from EarthSky News!

Long-term readers of this place will possibly recall that between April, 1989 and June, 1994 I lived on a Tradewind 33 sailing yacht Songbird of Kent. I have written before about those days.

Songbird of Kent. My home for five years.

When sailing at night when the sky is clear it is impossible not to feel deeply connected to the stars above one’s head.

My logbook for Songbird of Kent reports that at noon on Wednesday, 1st June, 1994, I departed the yacht harbour at Horta in The Azores bound for Plymouth, South-West England. Plymouth was 1,257 nautical miles (2,329km/1,447 statute miles) from Horta.

Horta on Faial Island of the Azores

The logbook has an entry for the 6th June.

0400 Lat. 43 deg 25 minutes North, Long 22 deg 3 minutes West. Engine Off. Still no wind but must sleep after 19 hours of helming. 840 miles to run. Wind 2 knots from SW. Baro 1027 mb, Viz Good.

The visibility was wonderful and seeing the stars up in the night sky all around me, as in all 360 degrees about me, practically down to the horizon on this moonless night is an image still etched in my mind.

That’s why I want to republish this article that appeared on the blog EarthSky News yesterday.

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We are galaxy stuff

A new study – based on supercomputer simulations – reveals that each one of us may be made in part from matter that passes from one galaxy to another.

This image shows M81 (bottom right) and M82 (upper left), a pair of nearby galaxies where intergalactic transfer – transfer of materials between galaxies – might be happening. Image via Fred Herrmann.

Sagan famously said that we are made of star stuff. He meant the carbon, nitrogen and oxygen atoms in our bodies, as well as atoms of all other heavy elements, were created inside stars. Yet Sagan’s expression of this idea, which quickly became a cornerstone of popular culture, might not take the concept far enough. According to astrophysicists at Northwestern University, our origins are much less local than previously thought. In fact, according to their analysis – which they say is the first of its kind – we’re not just star stuff. We’re galaxy stuff.

This study is being published on July 26, 2017 (July 27 in the U.K.) by the peer-reviewed journal Monthly Notices of the Royal Astronomical Society.

The Northwestern researchers found that up to half of the matter in our Milky Way galaxy may come from distant galaxies. As a result, each one of us may be made in part from extragalactic matter. That is, atoms of carbon, nitrogen, oxygen and so on in our bodies may be created not just by stars in our own Milky Way galaxy, but by stars in far-flung galaxies.

They arrived at this conclusion using supercomputer simulations. The study required the equivalent of several million hours of continuous computing.

The simulations show that supernova explosions eject great quantities of gas from galaxies, which causes the atoms made inside stars to be transported from one galaxy to another via powerful galactic winds. According to their statement, intergalactic transfer is a newly identified phenomenon, which, they say, requires supercomputer simulations in order to be understood. According to these astrophysicists, this understanding is critical for knowing how galaxies evolve … and hence for knowing our own place in the universe.

Animation of gas flows around a Milky Way-like galaxy, as seen by the team’s computer simulations.

Daniel Anglés-Alcázar is a postdoctoral fellow in Northwestern’s Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA). He led the study, and he said:

It is likely that much of the Milky Way’s matter was in other galaxies before it was kicked out by a powerful wind, traveled across intergalactic space and eventually found its new home in the Milky Way.

Given how much of the matter out of which we formed may have come from other galaxies, we could consider ourselves space travelers or extragalactic immigrants.

Space is vast. Galaxies are located at almost inconceivable distances from each other. So, Alcázar and his team said, even though galactic winds propagate at several hundred kilometers per CIERA second, the process of intergalactic transfer occurs over billions of years.

As always, this new research built on earlier studies. Northwestern’s Claude-André Faucher-Giguère and his research group, along with a unique collaboration called Feedback In Realistic Environments (FIRE), had developed numerical simulations that produced realistic 3-D models of galaxies. These simulations followed a galaxy’s formation from just after the Big Bang to the present day.

Anglés-Alcázar then developed state-of-the-art algorithms to mine this wealth of data. In this way, he and his team were able to quantify how galaxies acquire matter from the universe.

The scientists say the prediction of intergalactic transfer can now be tested. The Northwestern team plans to collaborate with observational astronomers who are working with the Hubble Space Telescope and ground-based observatories to test the simulation predictions.

Simulated examples of intergalactic winds, shown as green string, in action around galaxies, shown as clusters of yellow dots. The galaxy at the center is ejecting the winds, blowing them toward potential the other galaxies.

Bottom line: Supercomputer simulations suggest that each one of us may be made in part from extragalactic matter. Hence, we are galaxy stuff.

ooOOoo

16th June, 1994

1945 Lat. 50 deg 21 minutes North, Long. 4 deg 10 minutes West. ARRIVED MAYFLOWER MARINA. Wind Nil. Baro 1023 Mb. Viz Good.

LOG CLOSED!

Mayflower Marina is at Plymouth.