All about flooble | fun stuff | Get a free chatterbox | Free JavaScript | Avatars    
perplexus dot info

Home > Science
Sunset Anomaly (Posted on 2016-03-09) Difficulty: 2 of 5
The cover of the June, 1979, issue of Sky and Telescope magazine had a 38-minute time exposure photo showing the setting sun over Boston harbor. It was taken on September 25, 1973, three days after the equinox.

click here

As the sun is then south of the equator, the sun's path in the sky should be an arc of a lesser circle (as opposed to a great circle, which would appear as a straight line on a photograph) centered on the south celestial pole, which is below the horizon, to the left (south). As a result, the concave side of the path should be toward the bottom/left. However the picture shows its concave side is on the top/right, toward the north celestial pole. What happened?

  Submitted by Charlie    
No Rating
Solution: (Hide)
When the sun is over 7° up in the sky, the earth's atmosphere doesn't have much of an effect on the position of a celestial body, but as the body (the sun in this instance) approaches the horizon, atmospheric refraction makes the body appear slightly higher in the sky, the effect reaching its maximum of about 1/2° when the body reaches the horizon. At just three days past the equinox, this bending of the lower portion of the path was sufficient to overcome the spherical geometric curvature in the other direction.

Comments: ( You must be logged in to post comments.)
  Subject Author Date
I feararmando2016-03-14 15:41:18
Thoughtsarmando2016-03-11 15:17:45
HiEzequiel havelles2016-03-10 00:54:55
Please log in:
Login:
Password:
Remember me:
Sign up! | Forgot password


Search:
Search body:
Forums (0)
Newest Problems
Random Problem
FAQ | About This Site
Site Statistics
New Comments (4)
Unsolved Problems
Top Rated Problems
This month's top
Most Commented On

Chatterbox:
Copyright © 2002 - 2017 by Animus Pactum Consulting. All rights reserved. Privacy Information