Mercury Transit - Little Guy gonna Fry

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Bsimon
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Mercury Transit - Little Guy gonna Fry

Post by Bsimon » Mon Nov 11, 2019 8:19 pm

Anyway that is how it looked even though Mercury was some 35 million miles away from the Sun. Mercury looked tiny this morning while transiting the Sun. (Mercury's diameter is about 1/285th the diameter of the Sun, much like comparing a bb to a beach ball.

I was surprised however just how large Mercury appeared. It did not look all that much smaller than what I remember Venus looking like during it's 2012 transit.

Here is a photo - shot thru an eyepiece attached to a Lunt white light filter (Herschel Wedge) attached to an Astro-Tech AT 102ED scope with a 700 mm focal length. The camera was my cell phone camera held up to the eyepiece. Earlier I used my University Optics 80 mm f/6.25 achromat with a Coronado h-alpha filter

Barry Simon
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IMG_8749.jpg
University Optics 80 mm f6.25 with h-alpha filter
IMG_8848 (4).jpg
Mercury Transit Image

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Bsimon
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Re: Mercury Transit - Little Guy gonna Fry

Post by Bsimon » Mon Nov 11, 2019 9:06 pm

Here is a quiz question for you mathematical geniuses - "Keeping Mercury directly between your line of sight and the Sun, how close would you have to be to Mercury for it to completely eclipse the Sun?

Prize to be awarded at the meeting for the first PAS member to respond correctly to this question.

Barry Simon

Lmccormick
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Re: Mercury Transit - Little Guy gonna Fry

Post by Lmccormick » Mon Nov 11, 2019 9:54 pm

Using the distance of 35 million miles from Mercury to the Sun, I'm going to guess that you would have to be no more than 123,113.62 miles from Mercury for it to cover the Sun.

Lowell McCormick

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Re: Mercury Transit - Little Guy gonna Fry

Post by Bjohnson » Tue Nov 12, 2019 9:53 pm

126,978.67 away, as a SWAG using 36 Million Miles from mercury to Sun and 3031 mile diameter of Mercury with 860,000 mile diameter of the sun and a lot of very rusty sophomore trig that I had forgotten too many years ago.

As my answer is very close to Lowell, I think I'm on track, but defer to him as he answered first, and we used rounded numbers that were a bit different.
Bill Johnson
PAS President, 2018-2019

dKern
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Re: Mercury Transit - Little Guy gonna Fry

Post by dKern » Thu Nov 14, 2019 12:59 am

Because of the eccentricity of Mercury's orbit, one cannot make an accurate calculation based on the average distance of Mercury from the Sun.
On the date of the transit, November 11, 2019, mercury was only 30,310 miles form the sun.
Therefore, on that specific date, one would have had to have been within 102,495 miles of Mercury for a total solar eclipse.
But that distance would be different on a different date.

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Bsimon
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Re: Mercury Transit - Little Guy gonna Fry

Post by Bsimon » Thu Nov 14, 2019 9:44 am

David, I think you meant to say the distance from Mercury to the Sun would be 30,310,000 not 30,310 miles.

I based my calculations on what references give as the average distance of Mercury from the Sun which most references give as 35,980,000 miles. Mercury, as David says varies fairly significantly in it's distance from the Sun as the diagram attached shows.

The diagram below illustrates the relative size appearance of the Sun from the Earth, Venus and Mercury as it would appear at both aphelion (furthest away) and perihelion (closest) distances. As you can see in the diagram even when it is furthest away from the Sun, the apparent diameter of the Sun would appear a bit over twice as large as it would appear from Earth. When at it's closest to the Sun, from Mercury the Sun would appear to be almost 4 times as large as it would appear to us in the sky.

By my calculations I get a distance from Mercury to the Sun of 35,980,000 miles as I noted above. This is the mean distance, not furthest away nor closest. Distances between bodies in space are measured from center to center, not surface to surface, so assuming that an observer on Mercury (if that were even possible) is observing the Sun at mid-day with the Sun equi-distant from both the northern and southern horizons. So in short, the Sun is directly overhead making it as close as possible on this mean distance day. This would drop the distance from the surface of Mercury to the 360 degree angular/apparent diameter of the Sun to a distance of 35,978,484 miles. (we do not subtract the distance in miles of the Sun's radius from the total distance as what we see that makes up the angular diameter is not a point on the surface, it is the plane of the total diameter running thru the center point of the Sun. Additionally from a point in space we are measuring out from a plane which runs thru the center point at Mercury's core to it's circumference as seen from space.

Using all of this data I get an apparent angular size of the Sun as seen from the surface of Mercury as 1.2021073 degrees. Then using that coupled with Mercury's diameter of 3032 miles (cited by most references), we would have to move out into space and placing Mercury directly between our line of sight and the Sun (with the Sun being at mean distance from Mercury) to a distance of 126,111.8704 miles. .8704 miles is equivalent to 4595 feet and a fraction over 8.5 inches :o . This 126,111 miles plus 4595 ft and 8.5+ inches would be the distance to the core of Mercury. Our embryonic fetus a la the scene from "2001, A Space Odyssey" would actually be just a mere 124,595 miles and a bit over 4593 additional feet above the surface of Mercury. When the embryonic baby blinks the distance may change somewhat! Double :o :o

So who got it right? As there are a fair number of variables are involved, all had the concept correct and knew or could research how to work the problem. So prizes to all who did that prior to my posting of this explanation.

Barry Simon
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IMG_8850.jpg
Solar appearance from Earth and inner planets

Lmccormick
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Re: Mercury Transit - Little Guy gonna Fry

Post by Lmccormick » Thu Nov 14, 2019 2:49 pm

I recalculated using the Mercury's closest and farthest distance from the Sun. At aphelion (43,382, 210 mi) the distance you'd have to be from Mercury to eclipse the Sun would be 152,599 miles and at perihelion (28,583,820 mi) you would be 100,544 miles away.

So if you put yourself in an orbit 100,000 miles beyond Mercury and were able to stay there, the Sun would be permanently eclipsed. How warm would it be a that location? Or would it be cold?

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