[HN Gopher] Nearby star's midlife crisis illuminates the future ...
___________________________________________________________________
Nearby star's midlife crisis illuminates the future of our own Sun
Author : rbanffy
Score : 51 points
Date : 2022-08-11 14:29 UTC (8 hours ago)
(HTM) web link (www.science.org)
(TXT) w3m dump (www.science.org)
| 8jef wrote:
| It's interesting to know _busy_ Sun periods can transition to
| _quiet_ ones. I wonder how these cycles can affect life on Earth,
| climate wise, in the long run... like, what has been leading to
| the _short ice age_ we had in the middle ages?
| tunap wrote:
| Great site for monitoring solar activities. Don't let the
| unobtrusive, old-school ads turn you off, it's a community
| college project trying to pay the bills.
|
| https://spaceweather.com/
|
| And, some info on the cycle:
|
| https://en.wikipedia.org/wiki/Solar_cycle
| dylan604 wrote:
| >Don't let the unobtrusive, old-school ads turn you off, i
|
| I especially like the ad for a 9 planets ring. Is that item
| old enough from when we had 9 planets, or is it a solid bit
| of defiance in accepting there's only 8 planets?
| mulmen wrote:
| Nobody is sure. Leading ideas are orbital cycles, decreased
| solar activity, increased volcanic activity, changes in ocean
| currents, re- or de-forestation as a result of declines in
| human population, and just the fact that climate is complex and
| variable.
|
| https://en.wikipedia.org/wiki/Little_Ice_Age#Possible_causes
| burlesona wrote:
| Right at the top of this article I found myself surprised by the
| idea that people in the 1600s had figured out a way to safely
| look at the sun through a telescope and make observations about
| sun spots.
|
| I don't know much about this, except that you can do it on a
| telescope today by putting in a solar lens, which looks basically
| opaque, as that's what it takes to reduce the light of the sun to
| something we can handle. I spent a while googling to figure out
| how they did it and got basically nothing.
|
| So, HN, does anyone know how the early telescope users figured
| this out? How many went blind trying different filtering
| approaches before they got a "just right" filter that let enough
| light through to observe the sun without hurting themselves?
| acegopher wrote:
| I believe it was done by projection onto a wall or screen, for
| example through a pinhole projection, rather than looking
| through a lens directly.
| KMnO4 wrote:
| I, and many others, learned a lot about the sun when during
| the last solar eclipse.
|
| I held a spice shaker lid (ie a disc with several round
| holes) into the sun and observed several crescent-shaped
| shadows on the ground [0]. It turns out the light that passes
| through the holes is a projection of the sun, which is kinda
| a neat realization. It was pretty unintuitive before I saw
| this, so I'm impressed by the 17th century astronomers.
|
| 0: Similar to https://www.researchgate.net/figure/A-cheese-
| grater-is-used-...
| theandrewbailey wrote:
| I was in Kentucky for the eclipse in 2017. I was looking
| around for a pin and some paper to do that, before I
| realized I was wearing a straw hat. It's a pinhole
| projector factory.
| trebbble wrote:
| Anyone who was near a tree during the eclipse saw that,
| too. The effect was very clear in spots of light passing
| through leaves. Definitely weird to see.
| r2_pilot wrote:
| Weird, but wonderful. I laid down a large (butcher paper)
| white sheet under a tree and took a picture. Much later
| on, I took that same picture and a pencil I had at the
| time, and projected the picture back onto the butcher
| paper and traced the picture back onto it. Pretty cool
| art!
| 7373737373 wrote:
| Check this out: https://youtu.be/X9_6EbucCPQ
|
| Cover your windows with opaque garbage bags, cut a small
| hole into one (<1in), and voila! Camera obscura!
| renewiltord wrote:
| I first discovered this for myself as a child when walking
| along a tree-lined path during the solar eclipse and seeing
| that the sunlight through the trees was crescent-shaped!
| Looking online, lots of people saw this too!
| shagie wrote:
| In searching for the info... Eye injuries of early solar
| observers - https://aty.sdsu.edu/vision/others.html
|
| https://en.wikipedia.org/wiki/Thomas_Harriot#Sunspots
|
| > Harriot observed the sunspot with the use of a telescope in a
| direct and hazardous way. ... Specifics as to how Harriot's
| telescope was set up remains largely unknown.
|
| This lead me to
| http://galileo.rice.edu/sci/observations/sunspots.html
|
| > Scheiner, a Jesuit mathematician at the university of
| Ingolstadt (near Augsburg), wished to preserve the perfection
| of the Sun and the heavens and therefore argued that sunspots
| were satellites of the Sun. They appeared as black spots when
| they passed in front of the Sun but were invisible at other
| points in their orbits. Their orbits had to be very close to
| the Sun for their shapes were foreshortened as they approached
| its edge. Scheiner observed sunspots through a telescope
| equipped with colored glasses.
|
| > ...
|
| > It was Castelli who developed the method of projecting the
| Sun's image through the telescope, a technique that made it
| possible to study the Sun in detail even when it was high in
| the sky.
|
| This was a very rapid development.
| https://en.wikipedia.org/wiki/Benedetto_Castelli
|
| > In December 1610, Galileo received a letter from Castelli,
| asking if the phases of Venus were observable through Galileo's
| new telescope.
|
| This then lead lead me to
| https://brunelleschi.imss.fi.it/itineraries/multimedia/Helio...
|
| > In his work on sunspots dated 1613, Galileo refers to the
| method invented by Benedetto Castelli for observing through the
| telescope and drawing--without damage to his eyes--the spots
| that he had discovered on the Sun's surface.
|
| > Galileo darkens the room and aims the telescope at the Sun.
| At about one meter from the eyepiece, he places a sheet of
| white paper. The solar disk is thus projected on the sheet. To
| heighten the contrast of the image and thus make it easier to
| observe, Galileo places a darkening screen around the sheet. He
| now draws a circle on the sheet with the compasses and, moving
| the sheet closer or farther away, he finds the position where
| the Sun's image exactly overlaps the circle. He then marks the
| sunspots on the sheet. Since the Sun moves, the helioscope
| itself must be moved continuously in order to keep the solar
| image in the circle.
| anonymousiam wrote:
| Because these things are probably cyclic, we may soon experience
| another Maunder Minimum and maybe even another ice age. (Those
| are cyclic too.)
| datavirtue wrote:
| "searching for stars in a similar stage could help identify other
| solar systems conducive to complex life."
|
| Then all you need is a way to detect planets that maintain a
| strong, protective magnetic field.
___________________________________________________________________
(page generated 2022-08-11 23:01 UTC)