lol ----- Original Message ----- From: "daniel turner" <outwest112@yahoo.com> To: utah-astronomy@mailman.xmission.com Sent: Wednesday, September 14, 2011 2:25:43 PM Subject: [Utah-astronomy] astro math I just lifted this picture from spaceweather.com. It shows a whimsical picture of a type often seen around the harvest moon. http://www.slas.us/gallery2/main.php?g2_itemId=4683 Its fun to shoot pictures like this but I like to figure out how far the camera was from the subject. It's easy but involves a little math. The wheelbarrow bed is about 40 inches long and the moon looks to be about 3/4th of that wide. We know that the moon is about a half degree wide. half a degree time pi and divided by 180 gives .0087 radians. One over radians gives 144. That times the 30 inches the moon appears to be wide give 3437.7 inches. Divided by 12 gives 286 feet. thats the rough distance between the camera and the wheelbarrow. Some times the subject is much farther away, like a climber on the side of a mountain or a car on a hillside. but the point is that the picture contains the information you need to find where the camera was at the time of the photo. DT _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.slas.us/gallery2/main.php