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Quiz Board...

Steven C.
NightSkyGuy
San Jose, CA
Post #: 877
I realize I never stated the answer to the last quiz.

Mohammed is correct. Since the sun is bright and Venus is the dark spot, a "Darken" mode stack in Photoshop or Darken mode with StarStax will composite the images together (provided they are already aligned).

As for which is the Sun's North pole, I'm not really sure.

There are a number of ways to surmise that the correct location of the sun's north pole must either be near middle left or middle, right. First since the sun and earth both rotate in the same direction, the Sun's "North Pole" is in the same direction as North on earth would be at noon. Even though the earth's rotational axis is tilted 21 degrees relative to the earth's orbit around the sun.

Since most of the apparent motion of Venus across the face of the sun is due to Venus's (faster) orbit around the sun I would guess that the top to bottom movement in the photo must correspond to an East to West passage of Venus across the face of the sun... That means north is on the right in the photo. Another clue is that photos from California ended when the sun set. When looking west, the north terrestial pole is to the right, so the sun's north terrestrial pole is also on the right.

If anyone has a better answer I'd love to hear it! There is some further discussion here.
Steven C.
NightSkyGuy
San Jose, CA
Post #: 878
PUZZLE 12: What Happened Here?

The first two photos below I used Image Stacker (or StarStax) against a slew of images. I then used Photoshop for the last image (though again, I could have used the forementioned programs)


What Happened Here?

What operations did I do to the top middle and bottom images?

NOTE: The bottom image was created using the two top images. In the bottom image not only is the sky much darker, but the few dozen hot pixels are gone.

HINT: I didn't use the healing tool!
HINT: In a few days I'll be publishing an article on the BLOG with the explanation.

Good luck.
john c.
user 13237391
Sunnyvale, CA
Post #: 44
the first picture used the brightest pixel for each location
the second one used the darkest pixel
the last one averaged the 2 pictures add and div by 2

good luck


john c
Steven C.
NightSkyGuy
San Jose, CA
Post #: 880
John is close. I spill the beans in my latest BLOG article.
Steven C.
NightSkyGuy
San Jose, CA
Post #: 897
PUZZLE 13: Which Way Is this Photo Facing?

In what direction was the camera pointing to take this photo? How do you know?


john c.
user 13237391
Sunnyvale, CA
Post #: 45
provided this is the northern hemisphere id say south to south west
the star trails imply that Polaris is out of the upper right corner of the frame

it would be easier in a larger picture(more pixels and zoomable)
there is a white light in the trees that may be the moon cant tell for sure
and the lighthouse keepers house is not in the picture

John Cincotta
Enrico
user 13025968
Fremont, CA
Post #: 158
West.
Steven C.
NightSkyGuy
San Jose, CA
Post #: 898
provided this is the northern hemisphere
It is. It's the Hatteras Lighthouse on the Outer Banks of North Carolina.

lighthouse keepers house is not in the picture
I don't know where or if the keepers quarters was moved when they moved the lighthouse 2900 feet from its original location, but only the visitor center would be visible even if you could see lower.

West
Correct, but how do you know?
john c.
user 13237391
Sunnyvale, CA
Post #: 46
star trails and the moon?? is that the moon in the trees?

star trails say e or w +- sunset I'm guessing says west

John Cincotta
Enrico
user 13025968
Fremont, CA
Post #: 159
West
Correct, but how do you know?

One clue is the horizon with being brighter in the middle of the picture and slightly colored clouds which means the picture was taken during sunset or sunrise (in northern hemisphere sunset would be West and sunrise East).
The next and more important clue is the angle of the star trails which you get only West in the northern hemispshere (northern celestial pole above horizon and southern celestial pole below horizon). The star trails show that the celestion pole left from the picture is below horizon and/or right from the picture above the horizon.
Also the star trails would be more curved if picture is taken closer to one of the celestial poles instead of almost straight as in the picture.
Celestial pole is the point in the sky where the stars appear to be rotating around when looked at from Earth.
The star trails East in the northern hemisphere would be reversed, pointing upper-right corner from/to lower-left corner.
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