APOD
Astronomy Picture of the Day
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
A Day in the Life of a (mostly) Human Sundial
Explanation: Have you ever wanted to be a gnomon? Of course, a gnomon is the tall part of a sundial that casts a shadow. The gnomon's shadow moves as the Sun moves across the sky, indicating time by the shadow's position on the dial face. So on July 19th , the Astronomy Group of the Progymnasium Rosenfeld created a human sundial, each participant patiently playing the role of the gnomon for 10 minutes. In this timelapse video of their temporal voyage of discovery , one image was taken every 20 seconds from 8 am until 4 pm Central European Summer Time. Drawn on the ground are the dial hour marks calculated to show the local time for that specific date. Behind, the tower clock offers a time check. Can you find the local time of solar noon? (Hint: At solar noon the Sun is on the meridan .) The persistent group plans a repetition of the human sundial performance next winter to compare the length of the day and the altitude of the Sun.
| Date | August 12, 2017 |
|---|---|
| Credit | Video Credit & Copyright: Astronomie-AG, Progymnasium Rosenfeld , Till Credner, AlltheSky.com |
| Authors & editors: | Robert Nemiroff (MTU) & Jerry Bonnell (UMCP) |
| A service of: |
ASD at NASA / GSFC, NASA Science Activation & Michigan Tech. U. |


