This is from NASA latest solar image “movies” available here. This shows a 48 hour time lapse of the surface of the sun, 15 October to 17 October 2018. The surface of the sun is currently “spotless” in that there are no “sunspots.” But as you can see, it is hardly featureless; in fact a coronal hole pointed our way may cause visible aurora if you live in a dark place close enough to the poles.
Showing posts with label astronomy. Show all posts
Showing posts with label astronomy. Show all posts
10/17/2018
Our 'Spotless' Sun
This is from NASA latest solar image “movies” available here. This shows a 48 hour time lapse of the surface of the sun, 15 October to 17 October 2018. The surface of the sun is currently “spotless” in that there are no “sunspots.” But as you can see, it is hardly featureless; in fact a coronal hole pointed our way may cause visible aurora if you live in a dark place close enough to the poles.
6/20/2017
Summer Solstice, Midsummer, &c.
Where I reside, at approximately 38° North Latitude, the actual length time between sunrise and sunset is identical (within half a minute) from 15 June to 25 June (and maybe beyond that, I didn’t check). Namely we have about 15 hours 32 minutes between sunrise and sunset – it seems longer because of long morning and evening twilight and often a lingering glow from atmospheric conditions in summer.
In modern astronomical terms, the solstice is defined in terms of the position of the earth in its orbit around the sun, as measured against the background of the fixed stars. So in 2017, the solstice occurs at 9:24 PM PDT on 20 June.
In ancient observational astronomical terms, the solstice is literally the apparent “standing still” of the sun at either end of its travel, over the course of the year, north and south on the ecliptic. Seeing the sun come up in the same spot for ten or more days is remarkable, compared to the day-to-day changes in equinoctial seasons (more rapidly changing position of sunrise/sunset as well as many minutes per day longer or shorter time of daylight). So the ancients marked the year with Midsummer celebrations at Summer Solstice, and with Midwinter celebrations (Yuletide) at the Winter Solstice.
Let me beat my “First Day of Summer” drum. In my attuned-to-ancient-Celtic brain, the first day of summer was the cross-quarter on Cinco de Mayo, more or less. First Day of Spring is Groundhog Day (Lunar New Year, more or less, depending on whether you’re a sun kind of person or a moon kind of person). First Day of Winter is actually around Guy Fawkes Day, November 5, plus or minus. And First Day of Autumn is August 6, Hiroshima Day – or if you prefer, the day on which the racist American President Lyndon Baines Johnson was dragged kicking and screaming and forced into signing the Voting Rights Act of 1965.
9/23/2015
Equi-Nox means [Day] Equals Night -- Right?
Wrap this around your mental astronomical-phenomena spindle and see if you can make of it more of a skein than a snarl:
Where I live on the west coast of the U.S.A., astronomical equinox is at 1:20AM Pacific Daylight Time on Wednesday 23 September 2015. The time from sunrise to sunset should be equal to the time from sunset to sunrise, right?
Doesn't work that way.
Wednesday actually has six more minutes of daylight than Friday. On Friday 25 September we actually get 12 hours zero minutes between sunrise and sunset.
Why?
First, the astronomical definition of equinox is at the moment the earth in its orbit around the sun crosses a particular point in reference to what astronomers call the fixed stars. We know that point wanders with respect to the earth's axis-wobble and the earth's elliptical orbit (precession of the equinox) -- ve-e-e-r-r-y s-slo-o-o-owly! But can it make a difference of a day or two?
Second, there's the spin of the earth. Does the spin, added to the round-the-sun motion, make a difference?
I admit I haven't done the research. But hey, give me some credit for finding the conundrum.
Where I live on the west coast of the U.S.A., astronomical equinox is at 1:20AM Pacific Daylight Time on Wednesday 23 September 2015. The time from sunrise to sunset should be equal to the time from sunset to sunrise, right?
Doesn't work that way.
Wednesday actually has six more minutes of daylight than Friday. On Friday 25 September we actually get 12 hours zero minutes between sunrise and sunset.
Why?
First, the astronomical definition of equinox is at the moment the earth in its orbit around the sun crosses a particular point in reference to what astronomers call the fixed stars. We know that point wanders with respect to the earth's axis-wobble and the earth's elliptical orbit (precession of the equinox) -- ve-e-e-r-r-y s-slo-o-o-owly! But can it make a difference of a day or two?
Second, there's the spin of the earth. Does the spin, added to the round-the-sun motion, make a difference?
I admit I haven't done the research. But hey, give me some credit for finding the conundrum.
5/30/2014
Relative Disaster
On 29 May 1919 there was a total eclipse of the sun that was visible in the southern hemisphere. A team of scientists with specially filtered telescopic cameras documented the event. What was super special about the cameras, apparently, was that the films showed not only the rim of the sun but also stars around the sun.
The stars weren't in their predicted positions.
This is the etymological essence of a "disaster": dis + aster (star). The appearance did not match the expectation.
Once that news came out, it was more widely accepted in the astronomy / physics community of scientists that the "unprovable" theory of a 40 year old German-born mathematician / physicist was demonstrably true. Albert Einstein's theory of relativity was fact, not just weird math. Light had been seen to have bent in the gravitational field of the sun.
So it is that 30 May is considered the "birthday" of general relativity. Oh the theory had been alive and kicking in the womb of mathematics since 1905, in all the glorious beauty of the Lorenz transformation, but 30 May is when it came out singing the praise of the Creator.
Space-time ain't flat.
But I'm still waiting for artificial gravity -- and anti-gravity!
The stars weren't in their predicted positions.
This is the etymological essence of a "disaster": dis + aster (star). The appearance did not match the expectation.
Once that news came out, it was more widely accepted in the astronomy / physics community of scientists that the "unprovable" theory of a 40 year old German-born mathematician / physicist was demonstrably true. Albert Einstein's theory of relativity was fact, not just weird math. Light had been seen to have bent in the gravitational field of the sun.
So it is that 30 May is considered the "birthday" of general relativity. Oh the theory had been alive and kicking in the womb of mathematics since 1905, in all the glorious beauty of the Lorenz transformation, but 30 May is when it came out singing the praise of the Creator.
Space-time ain't flat.
But I'm still waiting for artificial gravity -- and anti-gravity!
1/08/2014
Earlier sunrise
Where I live at approximately 38° North Latitude, I mark today ( 8 January ) as the genuine beginning of the short half of the year when the days are getting longer. Yes techinically the time between sunrise and sunset has been increasing since winter solstice ( 21 December ). But when sunrise comes a bit earlier, it feels like the days are getting longer.
Back on 7 December we experienced the earliest sunset of this dark corner of the year. Not until today did the time of sunrise begin to get earlier. By only a few seconds per day at first, soon the days will be noticably longer. That makes me happy. Hopeful.
The science of how this is so can be explained by the analemma.
Back on 7 December we experienced the earliest sunset of this dark corner of the year. Not until today did the time of sunrise begin to get earlier. By only a few seconds per day at first, soon the days will be noticably longer. That makes me happy. Hopeful.
The science of how this is so can be explained by the analemma.
9/25/2013
NYT: Which Planet are you on?
And which sun are you looking at?
The New York Times' Kenneth Chang writes:
From the Big Bear Solar Observatory solar activity report:
The image here looks different than the plain yellow circle published by the NYT.
Solar maximum has to do with sciencey lingo about long-term solar weather patterns, not today's or this week's or this month's solar weather.
Note that some of my links above will always show the latest information, and conditions change. Talking about solar weather is still, well, talking about the weather. If you hunt around the N3KL site or the BBSO site you can find archive information by date.
I wonder what NYT headline we may see in January: "What Lind of Winter is This? No Killer Blizzard in Weeks!"
The New York Times' Kenneth Chang writes:
A week ago, a solitary sunspot blemished an otherwise blank yellow disk. In the ensuing days, a few more specks appeared, but even a small explosion, or coronal mass ejection, last Thursday seemed like the halfhearted effort of a slacker star.Say what? While it is true that there have not been flares pointed at us lately, that does not denote a lack of solar weather.
From the Big Bear Solar Observatory solar activity report:
BBSO Solar Activity Report 24 September 2013 19:21:45 UTThe NOAA positions listed above are trackable solar weather systems moving across the surface of our favorite fusion engine. These areas are active. These areas produce X-rays and particle streams that cause the current state of the earth's magnetosphere to be listed as "unsettled".
Solar activity is low. No significant flare events have been observed overnight or so far today. No significant flare events are expected today.
NOAA 11849, N19 W33 (X= 494,Y= 217). Beta region.
NOAA 11846, S18 W13 (X= 205,Y=-402). Alpha region.
NOAA 11850, N08 E15 (X=-246,Y= 21). Beta region.
NOAA 11851, S16 E46 (X=-663,Y=-340). Alpha region.
Positions as of September 24, 2013 at 15:00 UT.
JV
The image here looks different than the plain yellow circle published by the NYT.
Solar maximum has to do with sciencey lingo about long-term solar weather patterns, not today's or this week's or this month's solar weather.
Note that some of my links above will always show the latest information, and conditions change. Talking about solar weather is still, well, talking about the weather. If you hunt around the N3KL site or the BBSO site you can find archive information by date.
I wonder what NYT headline we may see in January: "What Lind of Winter is This? No Killer Blizzard in Weeks!"
2/02/2013
Cross-Quarter in Spring
Imbolc (say it "ih-molg") is the astronomical cross-quarter between
the Winter Solstice and the Spring Equinox. In Ireland it is called St. Brigid's day -- St. Brigit of Kildare, that is.
My ancient ancestors divided each golden year into "pieces of eight", as it were. They marked and celebrated the ongoing life and the cycle of the seasons. Don't put too much stock in self-styled neo-pagan (read "Victorian") trappings draped on solid archaeo-astronomy.
In 2013, the spring cross-quarter actually occurs 3 February at 15:57 UTC. Its actual date varies because of the vagaries our leap-year calendar.
As a result, celebration of the cross-quarter varies by culture. In Ireland, St. Brigid's day is the First of February. In Asia, the new moon following the spring cross-quarter is the start of the new year (e.g., Tet in Vietnam).
At our house, we celebrate the cross-quarter on Groundhog Day. After all, the cross-quarter is the original reason for the hooplah this morning in Punxsutawney, Pennsylvania, USA.
My ancient ancestors divided each golden year into "pieces of eight", as it were. They marked and celebrated the ongoing life and the cycle of the seasons. Don't put too much stock in self-styled neo-pagan (read "Victorian") trappings draped on solid archaeo-astronomy.
In 2013, the spring cross-quarter actually occurs 3 February at 15:57 UTC. Its actual date varies because of the vagaries our leap-year calendar.
As a result, celebration of the cross-quarter varies by culture. In Ireland, St. Brigid's day is the First of February. In Asia, the new moon following the spring cross-quarter is the start of the new year (e.g., Tet in Vietnam).
At our house, we celebrate the cross-quarter on Groundhog Day. After all, the cross-quarter is the original reason for the hooplah this morning in Punxsutawney, Pennsylvania, USA.
1/10/2013
Friday - dark of the moon
New Moon on 11 January 2013 at 11:44 a.m. Pacific Standard Time.
You know: Because! Inquiring minds! Need! To know!
You know: Because! Inquiring minds! Need! To know!
1/07/2013
I saw the light, yes...
7 January is a red letter day in my personal cosmo-chronological calendar. Today is the day (where I live) when not only is the time of sunset later than it was yesterday, but the time of sunrise is also earlier than it was yesterday. (Confused yet?)
The Days of Darkness are officially ended!
Bright beautiful days are all lined up out there ready to enjoy in 2013! Now there is real reason for hope.
The Days of Darkness are officially ended!
Bright beautiful days are all lined up out there ready to enjoy in 2013! Now there is real reason for hope.
12/13/2012
New Moon Time
New Moon (lunar/solar conjunction) was at 12:42 AM Pacific Standard time.
I always feel better once the moment of New Moon is past. Not that I'm all astrological or anything. It's just that, well the brain being mostly fluid, I am sensitive to the movement of the tides, including brain tides.
Besides, back in the days of playing NetHack, the program would note the system date, calculate the phase of the moon, and titrate the number and severity of enemies in your dungeons according to the degree of darkness of the moon. "You're in luck, full moon tonight!" was a good message to see at the beginning of a NetHack session.
If you know what this is . . . then you'll know what this is!
Happy New Moon! Don't party too hard.
I always feel better once the moment of New Moon is past. Not that I'm all astrological or anything. It's just that, well the brain being mostly fluid, I am sensitive to the movement of the tides, including brain tides.
Besides, back in the days of playing NetHack, the program would note the system date, calculate the phase of the moon, and titrate the number and severity of enemies in your dungeons according to the degree of darkness of the moon. "You're in luck, full moon tonight!" was a good message to see at the beginning of a NetHack session.
If you know what this is . . . then you'll know what this is!
Happy New Moon! Don't party too hard.
12/04/2012
The Dark of the Year
Depending on where you live, places in the northern hemisphere are experiencing their earliest sunsets around now. In Miami, Florida, the earliest sunset was back around November 29. In Seattle, Washington, the earliest sunset is not until December 10. In San Francisco, the earliest sunset is around December 7.
The latest sunrise for Seattle is about January 1; for Miami it's not until January 12; for San Francisco, it's about January 6.
Mid-winter, the winter solstice, is on December 21 at 11:12 Greenwich Mean Time. That's the "shortest day of the year" but due to astronomical sciencey stuff called the analemma, the day of earliest sunset, the day of solstice, and the day of latest sunrise are not the same (unless you live on the equator, where all days are 12 hours long!).
I am always glad when the earliest sunset is past, even though it only varies by much less than a minute per day when the sun is rounding the corner of the analemma, as it were. I'm glad because I tend to do more of my non-employment-related outdoor activity in the evening, and even a few more seconds of light gives me some hope that the evenings will soon be noticeably brighter.
May your days be merry and bright!
The latest sunrise for Seattle is about January 1; for Miami it's not until January 12; for San Francisco, it's about January 6.
Mid-winter, the winter solstice, is on December 21 at 11:12 Greenwich Mean Time. That's the "shortest day of the year" but due to astronomical sciencey stuff called the analemma, the day of earliest sunset, the day of solstice, and the day of latest sunrise are not the same (unless you live on the equator, where all days are 12 hours long!).
I am always glad when the earliest sunset is past, even though it only varies by much less than a minute per day when the sun is rounding the corner of the analemma, as it were. I'm glad because I tend to do more of my non-employment-related outdoor activity in the evening, and even a few more seconds of light gives me some hope that the evenings will soon be noticeably brighter.
May your days be merry and bright!
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