#perihelion — Public Fediverse posts
Live and recent posts from across the Fediverse tagged #perihelion, aggregated by home.social.
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The new #Kreutz #comet is now C/2026 A1 (MAPS): http://www.cbat.eps.harvard.edu/iau/cbet/005600/CBET005658.txt and https://www.spaceobs.com/en/Alain-Maury-s-Blog/The-discovery-of-comet-C-2026-A1-MAPS and https://www.minorplanetcenter.net/mpec/K26/K26BC9.html - whether it will reach and survive #perihelion is highly uncertain but there is hope as https://www.facebook.com/groups/227002358661288/posts/1670699484291561 and https://groups.io/g/comets-ml/topic/117373975#msg34667 explain. And if MAPS makes it to perihelion and is (very) bright then coronagraphs on the ground might be able to catch it against the inner corona as the following table - calculated with https://ssd.jpl.nasa.gov/horizons/app.html#/ - shows.
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https://www.europesays.com/ie/293412/ 3I/ATLAS Shows Signs of Full Cometary Awakening after Perihelion ##Perihelion #3IATLAS #CarbonDioxide #CarbonMonoxide #comet #Cyanide #Éire #Ice #IE #InterstellarComet #InterstellarObject #Ireland #nasa #OrganicMatter #Science #SolarSystem #SPHEREx #Water
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Not the most exciting post as I'm mainly working on boring stuff like drains and construction tasks at the moment. Here's December's update. We have had a huge dump of snow here in Orkney though since I wrote this.
https://northernlatitudes.scot/winter-is-coming/
#winter #scotland #solstice #science #astronomy #perihelion #aphelion
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We have passed #Perihelion today, Saturday, 3 January 2026, at 17:15 UT.
Happy Perihelion if you are celebrating 🙂🖖
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#Earth's #Perihelion occurs today (in fact in just under three and a half hours from the time of writing) at 17:15Z. That’s when our planet is at its closest to the #Sun, at around a distance of 147 million km. The mean is about 150 million km and the maximum (aphelion) will occur precisely half a year from now and we’ll be about 152 million km from it. A difference of 5 million km sounds a lot but the Earth’s orbit is almost circular with and #eccentricity of just 0.0167.
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Happy Perihelion everyone! Like in recent years I celebrated this orbital holiday with a sea swim in Exmouth.
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Perihelion:
"Earth will reach its closest point to the sun, known as perihelion, on Jan. 3, 2026, at 12:15 p.m. EST (1715 GMT)."
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Seeing a startling number of mentions of tomorrow's perihelion. Feeling like I missed the announcement of some loony prophecy.
#perihelion -
Sunrise, Sunset, Solstice and Perihelion
I was on the train earlier today when I remembered that we are getting close to the time when Earth reaches its perihelion, i.e. the point in its orbit when it is closest to the Sun. This occurs at 17.15 GMT tomorrow (Saturday 3rd January 2026), in fact. At this time the distance from the Sun’s centre to Earth’s centre will be 147,099,894 km This year, aphelion (the furthest distance from the Sun) is at 18.30 GMT on July 6th 2026 at which point the centre of the Earth will be 512,087,774 km from the centre of the Sun. You can find a list of times and dates of perihelion and aphelion for future years here.
Earth’s elliptical orbit viewed at an angle (which makes it look more eccentric than it is – in reality is very nearly circular).At perihelion the speed of the Earth in its orbit around the Sun is greater than at aphelion (about 30.287 km/s versus 29.291 km/s). This difference, caused by the Earth’s orbital eccentricity, contributes to the difference between mean time and solar time which, among other things, influences the time of sunrise and sunset at the winter solstice that happened a couple of weeks or so ago.
Incidentally, although the Solstice took place on 21st December, it was not until the end of 2025 that we experienced the latest sunrise. The longest day means neither the latest sunrise nor the earliest sunset. The earliest sunset was actually on December 15th in Dublin.
It surprises me how many people think that the existence of the seasons has something to do with the variation of the Earth’s distance from the Sun, thinking that the closer to the Sun we get the warmer the weather will be. The fact that perihelion occurs in the depth of winter should convince anyone living in the Northern hemisphere that this just can’t be the case, as should the fact that it’s summer in the Southern hemisphere while it is winter in the North.
The real reason for the existence of seasons is the tilt of the Earth’s axis of rotation. I used to do a little demonstration with a torch – flashlight to American readers- to illustrate this when I taught first-year astrophysics. If you shine a torch horizontally at a piece of card it will illuminate a patch of the card. Keep the torch at the same distance but tilt the card and you will see the illuminated patch increase in size. The torch is radiating the same amount of energy but in the second case that energy is spread over a larger area than in the first. This means that the energy per unit area incident on the card is decreases when the card is tilted. It is that which is responsible for winter being colder than summer. In the summer the Sun is higher in the sky (on average) than in winter. From this argument you can infer that the winter solstice not the perihelion, is the relevant astronomical indicator of winter.
That is not to say that the shape of the Earth’s orbit has no effect on terrestrial temperatures. It may, for example, contribute to the summer in the Southern hemisphere being hotter than in the North, although it is not the only effect. The Earth’s surface possesses a significant North-South asymmetry: there is a much larger fraction of ocean in the Southern hemisphere, for example, which could be responsible for moderating any differences in temperature due to insolation. The climate is a non-linear system that involves circulating air and ocean currents that respond in complicated ways and on different timescales not just to insolation but to many other parameters, including atmospheric composition (especially the amount of water vapour).
The dates when Earth reaches the extreme points on its orbit (the apsides) are not fixed because of the variations in its orbital eccentricity so, in the short-term, the dates can vary up to 2 days from one year to another. The perihelion distance varies slightly from year to year too; it will be slightly larger next year than this year, for example. There is however a long-term trend for perihelion to occur later in the year. For example, in 1246, the December Solstice (Winter Solstice for the Northern Hemisphere) was on the same day as the Earth’s perihelion. Since then, the perihelion and aphelion dates have drifted by an average of one day every 58 years. This trend will continue, meaning that by the year 6430 the timing of the perihelion and the March Equinox will coincide, although I hope to have retired by then…
#astronomy #ellipticalOrbits #perihelion #solstice #WinterSolstice
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Sunrise, Sunset, Solstice and Perihelion
I was on the train earlier today when I remembered that we are getting close to the time when Earth reaches its perihelion, i.e. the point in its orbit when it is closest to the Sun. This occurs at 17.15 GMT tomorrow (Saturday 3rd January 2026), in fact. At this time the distance from the Sun’s centre to Earth’s centre will be 147,099,894 km This year, aphelion (the furthest distance from the Sun) is at 18.30 GMT on July 6th 2026 at which point the centre of the Earth will be 512,087,774 km from the centre of the Sun. You can find a list of times and dates of perihelion and aphelion for future years here.
Earth’s elliptical orbit viewed at an angle (which makes it look more eccentric than it is – in reality is very nearly circular).At perihelion the speed of the Earth in its orbit around the Sun is greater than at aphelion (about 30.287 km/s versus 29.291 km/s). This difference, caused by the Earth’s orbital eccentricity, contributes to the difference between mean time and solar time which, among other things, influences the time of sunrise and sunset at the winter solstice that happened a couple of weeks or so ago.
Incidentally, although the Solstice took place on 21st December, it was not until the end of 2025 that we experienced the latest sunrise. The longest day means neither the latest sunrise nor the earliest sunset. The earliest sunset was actually on December 15th in Dublin.
It surprises me how many people think that the existence of the seasons has something to do with the variation of the Earth’s distance from the Sun, thinking that the closer to the Sun we get the warmer the weather will be. The fact that perihelion occurs in the depth of winter should convince anyone living in the Northern hemisphere that this just can’t be the case, as should the fact that it’s summer in the Southern hemisphere while it is winter in the North.
The real reason for the existence of seasons is the tilt of the Earth’s axis of rotation. I used to do a little demonstration with a torch – flashlight to American readers- to illustrate this when I taught first-year astrophysics. If you shine a torch horizontally at a piece of card it will illuminate a patch of the card. Keep the torch at the same distance but tilt the card and you will see the illuminated patch increase in size. The torch is radiating the same amount of energy but in the second case that energy is spread over a larger area than in the first. This means that the energy per unit area incident on the card is decreases when the card is tilted. It is that which is responsible for winter being colder than summer. In the summer the Sun is higher in the sky (on average) than in winter. From this argument you can infer that the winter solstice not the perihelion, is the relevant astronomical indicator of winter.
That is not to say that the shape of the Earth’s orbit has no effect on terrestrial temperatures. It may, for example, contribute to the summer in the Southern hemisphere being hotter than in the North, although it is not the only effect. The Earth’s surface possesses a significant North-South asymmetry: there is a much larger fraction of ocean in the Southern hemisphere, for example, which could be responsible for moderating any differences in temperature due to insolation. The climate is a non-linear system that involves circulating air and ocean currents that respond in complicated ways and on different timescales not just to insolation but to many other parameters, including atmospheric composition (especially the amount of water vapour).
The dates when Earth reaches the extreme points on its orbit (the apsides) are not fixed because of the variations in its orbital eccentricity so, in the short-term, the dates can vary up to 2 days from one year to another. The perihelion distance varies slightly from year to year too; it will be slightly larger next year than this year, for example. There is however a long-term trend for perihelion to occur later in the year. For example, in 1246, the December Solstice (Winter Solstice for the Northern Hemisphere) was on the same day as the Earth’s perihelion. Since then, the perihelion and aphelion dates have drifted by an average of one day every 58 years. This trend will continue, meaning that by the year 6430 the timing of the perihelion and the March Equinox will coincide, although I hope to have retired by then…
#astronomy #ellipticalOrbits #perihelion #solstice #WinterSolstice
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Mysterious Comet 3I/ATLAS to reach Sun's perihelion soon: What makes this position so special
https://atlas.whatip.xyz/post.php?slug=mysterious-comet-3iatlas-to-reach-suns-perihelion-soon-what-makes-this-position-so-special
"Unveiling the Mysteries: Comet 3I/ATLAS' Epic Journey to Sun's Perihelion"
#space #astronomy #comet #perihelion #interstellar -
Rapid Brightening of 3I/Atlas Ahead of Perihelion
https://arxiv.org/abs/2510.25035
#HackerNews #RapidBrightening #3IAtlas #Perihelion #Astronomy #SpaceScience
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Earlier this week, Comet C/2024 G3 (ATLAS) made its closest approach to the Sun.
While doing so, it made a dramatic appearance sweeping through the wide-field LASCO C3 coronagraph of the ESA/NASA SOHO mission over a few days.
Here’s my take, a triplet of Deep Red, Orange, & Blue filter images taken over an hour around 09:00UTC on 14 January, as an RGB composite.
#C2024G3 💫
#CometATLAS ☄️
#Perihelion 🌞
#Photography 📷
#SpaceScience 🛰️ -
This morning we were at Perihelion, the point at which Earth is closest to the sun, about 91.4 million miles (147 million km). I wrote an article that describes this further.
https://weather.chadcalsyn.com/blog/what-are-perihelion-and-aphelion/ -
Today is Perihelion Day, when the earth is closest to the sun. Our orbit is barely elliptical, so we're only 3% closer to the sun than we are in July. But, that little bit of extra warmth is welcome in the Northern Hemisphere, where it is currently winter. #Perihelion #sun #earth
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#perihelion in 15 mins!
I'm watching the distance between the Earth and the Sun go down, then up!
https://theskylive.com/sun-info#distance -
Happy #Perihelion Day to all who oscillate!
Our good ship Earth will be closer to Mother Sun today (Sat 4 January 2025) than at any other point in the year, thanks to our frankly flaky elliptical orbit. (At 13:28 GMT, to be precise.)
Do not climb a ladder today, lest your hair be singed.
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Kometen C/2023 A3 (Tsuchinshan-Atlas):
• Entdeckung: Januar 2023 vom Tsuchinshan-Observatorium (China) und ATLAS-Projekt (Hawaii).• Sonnennähe: Erreicht am 12. Oktober 2024 das Perihelion (nächster Punkt zur Sonne).
• Sichtbarkeit: Möglich ab September 2024, könnte mit bloßem Auge sichtbar sein.
• Erdnähe: Am 13. Oktober 2024 etwa 72 Millionen km von der Erde entfernt.
#Komet2024 #C2023A3 #TsuchinshanAtlas #Weltraum #Astronomie #Himmelsereignis #Perihelion #SichtbarkeitKomet -
If we get some clear nights in soon, Comet 13P Olbers is a nice target for smaller telescopes as it could be near +7th magnitude when it reaches its closest point to the sun (perihelion) on June 30th. The comet has been making the 69-year circuit for millions of years with an orbit that takes it way past the orbit of Neptune. It should be easier to find on July 5th when it passes near the +4th magnitude star 10 Ursae Majoris.
https://www.universetoday.com/166998/catching-comet-13p-olbers-this-summer/
#Comet #13P #Olbers #Telescope #universetoday #Neptune #perihelion #WestportObservatory #WestportCT #WestportAstronomicalSociety
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Prepárate para un nuevo viaje en el mundo de #ExpedienteX ya que #FoxMulder y #DanaScully regresarán en #TheXFiles #Perihelion https://www.cinemascomics.com/expediente-x-regresa-con-perihelion/
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Prepárate para un nuevo viaje en el mundo de #ExpedienteX ya que #FoxMulder y #DanaScully regresarán en #TheXFiles #Perihelion https://www.cinemascomics.com/expediente-x-regresa-con-perihelion/
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#TheMetalDogArticleList
#MetalInjection
DØDHEIMSGARD Returns With Cosmic New Single "Abyss Perihelion Transit"
As experimental as ever.#Dodheimsgard #Cosmic #Abyss #Perihelion #Transit #NewMusic #Metal #MusicNews
