Sub solar point ?

[jacoblarsen93]

Hello everybody 

Last year i was in Australia workin in a underground gold mine for at few Months 

Down in the mine we observed That one Day it suddenly lit up down there (about 150 feet or 50 m). We didn't Think much of it then as the time was about midday but then i just heard about the sub solar point and was wondering if That actually was happening right there? That sun was shining straight down the shaft. But how large and area is the sub solar point? 

Best regards Jacob 

 

[spaceman_spiff]

If the mine shaft was exactly vertical relative to the ground then the Sun would have to be exactly overhead to illuminate the bottom of the mine (and you would be at the sub solar point). If there is any angle in the mineshaft then you would not be at the sub solar point. As for the size of the sub solar point, it is really a line that crosses the Earth each day, I don't think it really has a width.

Hope that helps

Dan.

 

 

[JamesM]

Hi Jacob and welcome to the forum.

Clear skies

[DRT]

This is possible if you were in northern Australia, on or north of the Tropic of Capricorn, in the summer months of the southern hemisphere.

This video explains why and also gives you a way of working it out for your location and time of year:

 

 

[Stub Mandrel]

I've heard there's a Well in Alexandria that is sub-solar once a year :-)

[laudropb]

Hello and a warm welcome to the SGL. That's a very interesting post. It is possible that it was a sub polar point but more details are necessary to be sure.

[Pete Presland]

Hi welcome to SGL from Pete in Bedfordshire, an interesting topic to open on.

[acey]

Very interesting, it does sound as if you had the sun directly overhead, which is possible (at the right time of year) in any part of Australia north of the Tropic of Capricorn. If there had been another deep hole next to yours then people at the bottom of it would have seen exactly the same effect at the same time. That's because the sun is so far from us that its rays are effectively parallel, and a mine shaft is wide enough to allow for some variation in where the sun needs to be in order to be visible from the bottom. This means that you weren't necessarily at the subsolar point, but you must have been close to it. Assuming, of course, that the mine shaft was actually vertical.

[Stub Mandrel]

Hi Jacob, roughly how wide was the shaft?

A 2 meter wide shaft 50m deep will 'scan' a strip of sky about 4.5 degrees wide, so the sun would reach a point at the bottom of the vertical shaft with the sun within two and quarter degrees of directly overhead, so anywhere within about 250km radius of the sub-solar point. Obviously the nearer to directly overhead, the longer the lighting up would last - exactly on the line it would be visible for about 20 minutes while at the edge of the area it would only be a brief glimpse of the sun.

The smaller and deeper the shaft, the closer it needs to be to the subsolar point.

So you must have been fairly close, but perhaps not dead on.

[Dave Lloyd]

Hi Jacob, welcome.

[jacoblarsen93]

Hey thanks you for all the feedback. 

It was indeed in the nothern Australia. A mining location called Miclere near the city Clermont. 

The shaft was about 2x3m and was perfectly straight as we were hoist down on a "chair" 

It happened at around christmas i Think it was the 21st 2014

In the picture you can see the wholeclothing underground illuminated by the sun. (Not from my headlamp)

My friends and i shoveled 5 tonnes of dirt that Day from 100m in the mine

Greetings from Denmark

[DRT]

1 hour ago, jacoblarsen93 said:

Hey thanks you for all the feedback. 

It was indeed in the nothern Australia. A mining location called Miclere near the city Clermont. 

The shaft was about 2x3m and was perfectly straight as we were hoist down on a "chair" 

It happened at around christmas i Think it was the 21st 2014

In the picture you can see the wholeclothing underground illuminated by the sun. (Not from my headlamp)

My friends and i shoveled 5 tonnes of dirt that Day from 100m in the mine

Greetings from Denmark

 

The video I posted above says that Sub Solar hits the Tropic of Capricorn on 21st Dec. Clermont is at 22.8 degrees south, which is less than one degree north of the tropic at 23.5. It is therefore highly likely that you experienced at least "almost" Sub Solar, and probably very close to true Sub Solar given the depth and relatively narrow shaft. The picture is intriguing as it shows you head lamp shining slightly upwards but a clear shadow of you on the roof and light shining directly onto the tops of each of the rungs on the ladder going up the shaft.

very cool

 

[saac]

I had never heard of the sub solar point before - that's what I love about this place, everyday is a school day  Welcome Jacob what a cracking post and a really interesting experience you had in Australia.

Jim

[acey]

Great photo and fascinating story. This link gives the latitude and longitude of Miclere Goldfield as

22° 33' 50" S

147° 32' 41" E

http://www.bonzle.com/c/a?a=p&p=268232&d=faq&cmd=sp&c=1&x=147.54478&y=-22.56381&w=40000&mpsec=0

That's just north of the Tropic of Capricorn (23.5 deg south), so the Sun should get exactly overhead there around southern mid-summer. The co-ordinates can be entered here to give the angle of the Sun above the horizon for any date and time:

http://www.esrl.noaa.gov/gmd/grad/solcalc/azel.html

According to it, at Miclere on December 21 2014 the Sun reached a maximum 89.12 degrees above horizon at 12.08.

[Stub Mandrel]

Your luck to be really close to the tropical line more or less on the solstice!

[Starwiz]

Welcome to the SGL!  

John

[glowjet]

Hi Jacob and welcome to SGL, enjoy the forum