APOD: Solstice Sun and Milky Way (2021 Dec 21)

Comments and questions about the APOD on the main view screen.
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APOD: Solstice Sun and Milky Way (2021 Dec 21)

Post by APOD Robot » Tue Dec 21, 2021 5:05 am

Image Solstice Sun and Milky Way

Explanation: Welcome to December's solstice, first day of winter in the north and summer for the southern hemisphere. Astronomical markers of the seasons, solstice and equinox dates are based on the Sun's place in its annual journey along the ecliptic, through planet Earth's sky. At this solstice, the Sun reaches its maximum southern declination of -23.5 degrees today at 15:59 UTC, while its right ascension coordinate on the celestial sphere is 18 hours. That puts the Sun in the constellation Sagittarius in a direction near the center of our Milky Way galaxy. In fact, if you could see today's Solstice Sun against faint background stars and nebulae (that's really hard to do, especially in the daytime ...) your view might look something like this composited panorama. To make it, images of our fair galaxy were taken under dark Namibian night skies, then stitched together in a panoramic view. From a snapshot made on 2015 December 21, the Sun was digitally overlayed as a brilliant star at today's northern winter solstice position, close to the center of the Milky Way.

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Ann
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Re: APOD: Solstice Sun and Milky Way (2021 Dec 21)

Post by Ann » Tue Dec 21, 2021 6:00 am

This is my favorite solstice APOD ever!

Where is the Sun during winter solstice? Take a look at this APOD!

Ann
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Re: APOD: Solstice Sun and Milky Way (2021 Dec 21)

Post by orin stepanek » Tue Dec 21, 2021 12:27 pm

WinterSolsticeMW_Seip_1079.jpg
406370303.jpg
Have a great solstice everybody!! :wink:
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Orin

Smile today; tomorrow's another day!

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Re: APOD: Solstice Sun and Milky Way (2021 Dec 21)

Post by Sa Ji Tario » Tue Dec 21, 2021 1:55 pm

Today at 12.57 am from my lares (15.57 pm UTC) the Sun will be at the tip of the Arcitenens sagite pointing to the heart of the Scorpion that killed his friend Orion and that is why Arcitenens, the Sagittarius will shoot the arrow of fire in revenge.
Between the Sun and the orange star, Antares, is the La Pipa Nebula and the rivers of dust that culminate in Rho Oph
From the indicated time, the Sun will begin to transit through the descending node until the June solstice.

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Re: APOD: Solstice Sun and Milky Way (2021 Dec 21)

Post by De58te » Tue Dec 21, 2021 3:39 pm

A question pops up for me. In ancient times the year was considered to start on the vernal equinox when the Sun was in Pisces. Therefore it is said we are in the Age of Pisces and coming up is the dawning of the Age of Aquarius when the Sun moves over into that sign. However, in these modern times we usually acknowledge the start of the new year to follow this winter solstice. i.e. January 1st. So as the description says that the Sun is in Sagittarius now, doesn't that mean this is the Age of Sagittarius, and it is the Dawning of the Age of Scorpius?

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Re: APOD: Solstice Sun and Milky Way (2021 Dec 21)

Post by MarkBour » Tue Dec 21, 2021 4:35 pm

De58te wrote: Tue Dec 21, 2021 3:39 pm A question pops up for me. In ancient times the year was considered to start on the vernal equinox when the Sun was in Pisces. Therefore it is said we are in the Age of Pisces and coming up is the dawning of the Age of Aquarius when the Sun moves over into that sign. However, in these modern times we usually acknowledge the start of the new year to follow this winter solstice. i.e. January 1st. So as the description says that the Sun is in Sagittarius now, doesn't that mean this is the Age of Sagittarius, and it is the Dawning of the Age of Scorpius?
I'm looking forward to the song version. :-)
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Re: APOD: Solstice Sun and Milky Way (2021 Dec 21)

Post by neufer » Tue Dec 21, 2021 4:42 pm

De58te wrote: Tue Dec 21, 2021 3:39 pm
A question pops up for me. In ancient times the year was considered to start on the vernal equinox when the Sun was in Pisces. Therefore it is said we are in the Age of Pisces and coming up is the dawning of the Age of Aquarius when the Sun moves over into that sign. However, in these modern times we usually acknowledge the start of the new year to follow this winter solstice. i.e. January 1st. So as the description says that the Sun is in Sagittarius now, doesn't that mean this is the Age of Sagittarius, and it is the Dawning of the Age of Scorpius?
  • In ancient Roman Empire times the year was considered to start on January 1.
https://en.wikipedia.org/wiki/Ianuarius wrote:
<<Ianuarius, fully Mensis Ianuarius ("month of Janus"), was the first month of the ancient Roman calendar, from which the Julian and Gregorian month of January derived. It was followed by Februarius ("February"). In the calendars of the Roman Republic, Ianuarius had 29 days. Two days were added when the calendar was reformed under Julius Caesar in 45 BCE. Ianuarius is conventionally thought to have taken its name from Janus, the dual-faced god of beginnings, openings, passages, gates and doorways

In the oldest Roman calendar, which the Romans believed to have been instituted by their legendary founder Romulus, the first month was Martius ("month of Mars", March), and the calendar year had only ten months. Ianuarius and Februarius were supposed to have been added by Numa Pompilius, the second king of Rome, originally at the end of the year. It is unclear when the Romans reset the course of the year so that January and February came first. Ianuarius is conventionally thought to have taken its name from Janus, the dual-faced god of beginnings, openings, passages, gates and doorways. From Ianus derived ianua ("door"), and hence the English word "janitor" (Latin, ianitor).

In England, the Angle, Saxon, and Viking invasions of the fifth through tenth centuries plunged the region back into pre-history for a time. After William the Conqueror became king in 1066, he ordered that January 1 be re-established as the civil New Year. Later, however, England and Scotland joined much of Europe to celebrate the New Year on March 25.>>
https://en.wikipedia.org/wiki/Astrological_age#Age_of_Pisces_(Piscean_Age) wrote:
<<The age of Pisces began c. 1 AD and will end c. 2150 AD.
https://www.firstpost.com/tech/science/earths-climate-by-year-2150-will-compare-to-warm-weather-50-million-years-ago-5714821.html wrote:
<<If our emissions continue unchecked, our climate by 2150 would compare
to the warm and nearly ice-free Eocene period 50 million years ago.
(And a sea level rise of 5m by 2150 cannot be ruled out!)
>>
With the story of the birth of Christ coinciding with 1 AD, many Christian symbols for Christ use the astrological symbol for Pisces, the fishes. Jesus bears many of the temperaments and personality traits of a Pisces, and is thus considered an archetype of the Piscean. Moreover, the twelve apostles were called the "fishers of men," early Christians called themselves "little fishes," and a code word for Jesus was the Greek word for fish, "Ikhthus."

The Age of Aquarius, in astrology, is either the current or forthcoming astrological age, depending on the method of calculation. Astrologers maintain that an astrological age is a product of the earth's slow precessional rotation and lasts for 2,160 years, on average (one Great Year equals 25,920-year period of precession / 12 zodiac signs = 2,160 years). There are various methods of calculating the boundaries of an astrological age. In sun-sign astrology, the first sign is Aries, followed by Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius, and Pisces, whereupon the cycle returns to Aries and through the zodiacal signs again. Astrological ages proceed in the opposite direction ("retrograde" in astronomy). Therefore, the Age of Aquarius follows the Age of Pisces. The 1967 musical Hair, with its opening song "Aquarius" and the line "This is the dawning of the Age of Aquarius", brought the Aquarian age concept to the attention of audiences worldwide. However, the song further defines this dawning of the age within the first lines: "When the Moon is in the seventh house and Jupiter aligns with Mars, then peace will guide the planets and love will steer the stars". Astrologer Neil Spencer denounced the lyrics as "astrological gibberish", noting that Jupiter aligns with Mars several times a year and the Moon is in the 7th House for two hours every day.>>
Art Neuendorffer

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Re: APOD: Solstice Sun and Milky Way (2021 Dec 21)

Post by Run! » Wed Dec 22, 2021 12:01 am

Oh nooo! Sgr A* has exploded!

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Re: APOD: Solstice Sun and Milky Way (2021 Dec 21)

Post by neufer » Wed Dec 22, 2021 4:41 pm

Click to play embedded YouTube video.
Run! wrote: Wed Dec 22, 2021 12:01 am
Oh nooo! Sgr A* has exploded!
Art Neuendorffer

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Re: APOD: Solstice Sun and Milky Way (2021 Dec 21)

Post by Fred the Cat » Wed Dec 22, 2021 11:41 pm

Today's APOD reminded me of a recent post. I was curious if we were high enough above the plane to notice the broad disc – minus the dust clouds?

After time to pause, I’m pretty sure I’m not high enough to notice. 8-) But that sun sure is bright! :yes:
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Re: APOD: Solstice Sun and Milky Way (2021 Dec 21)

Post by alter-ego » Thu Dec 23, 2021 2:36 am

Fred the Cat wrote: Wed Dec 22, 2021 11:41 pm Today's APOD reminded me of a recent post. I was curious if we were high enough above the plane to notice the broad disc – minus the dust clouds?

After time to pause, I’m pretty sure I’m not high enough to notice. 8-) But that sun sure is bright! :yes:
The disk thickness is ~1% (~1000 ly) of the galaxy's diameter. The Sun is above the disk plane by ~15 ly to 100 ly.
So, no we're not high enough. We're basically in the thick of it.
A pessimist is nothing more than an experienced optimist

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Re: APOD: Solstice Sun and Milky Way (2021 Dec 21)

Post by neufer » Thu Dec 23, 2021 3:18 pm

alter-ego wrote: Thu Dec 23, 2021 2:36 am
Fred the Cat wrote: Wed Dec 22, 2021 11:41 pm
Today's APOD reminded me of a recent post. I was curious if we were high enough above the plane to notice the broad disc – minus the dust clouds?

After time to pause, I’m pretty sure I’m not high enough to notice. 8-) But that sun sure is bright! :yes:
The disk thickness is ~1% (~1000 ly) of the galaxy's diameter. The Sun is above the disk plane by ~15 ly to 100 ly.
So, no we're not high enough. We're basically in the thick of it.
https://en.wikipedia.org/wiki/Thin_disk wrote:
<<The thin disk is a structural component of spiral and S0-type galaxies, composed of stars, gas and dust. It is the main non-centre (e.g. galactic bulge) density, of such matter. That of the Milky Way is thought to have a scale height of around 300–400 parsecs (980–1,300 ly) in the vertical axis perpendicular to the disk, and a scale length of around 2.5–4.5 kiloparsecs (8.2–14.7 kly) in the horizontal axis, in the direction of the radius. For comparison, the Sun is 8 kiloparsecs (26 kly) out from the center. The thin disk contributes about 85% of the stars in the Galactic plane and 95% of the total disk stars. It can be set apart from the thick disk of a galaxy since the latter is composed of older population stars created at an earlier stage of the galaxy formation and thus has fewer heavy elements. Stars in the thin disk, on the other hand, are created as a result of gas accretion at the later stages of a galaxy formation and are on average more metal-rich.

The thin disk contains stars with a wide range of ages and may be divided into a series of sub-populations of increasing age. Notwithstanding, it is considered to be considerably younger than the thick disk.

Based upon the emerging science of nucleocosmochronology, the Galactic thin disk of the Milky Way is estimated to have been formed 8.8 ± 1.7 billion years ago. It may have collided with a smaller satellite galaxy, causing the stars in the thin disk to be shaken up and creating the thick disk, while the gas would have settled into the galactic plane and reformed the thin disk.

Outside of the major spiral arms is the Monoceros Ring (or Outer Ring), a ring of gas and stars torn from other galaxies billions of years ago. However, several members of the scientific community recently restated their position affirming the Monoceros structure is nothing more than an over-density produced by the flared and warped thick disk of the Milky Way. The structure of the Milky Way's thick disk is warped along an "S" curve.>>
Art Neuendorffer