Physics Photo of the Week

November 11, 2022

Total Lunar Eclipse from May, 2022 - Revisited (Photos by Donald Collins)

The total lunar eclipse from May 15, 2022 is the feature PPOW for this week.  In the May post, an additional feature of all lunar eclipses is added.

Notice in the picture of the totally eclipsed Moon, we can see two stars.  Faint stars near the Moon are normally not visible in photographs of the normal un-eclipsed Moon, because the camera is overwhelmed by the Moon's extreme brightness compared with the stars.  The faint total eclipse permits the faint stars to be seen very close to the Moon,

 

I made a series of total eclipse images from last May's eclipse.  The first image (above) was taken soon after totality began; the last image was taken soon before totality ended - about 48 minutes after totality began.  The stars and the Moon are seen in each of these images which are displayed in an animated sequence below. 

If the telescope and camera were stationary, The stars would appear moving to the right due to the Earths diurnal (daily) rotation.  From a stationary telescope the Moon would also show movement to the right due to Earth's rotation, but the Moon would not appear to move as fast as the stars due to the Moon's monthly rotation about the Earth.  The telescope for this project has a clock drive to follow the stars' apparent motion in the sky.  The clock drive allows long time exposures to capture still images of the stars.  Notice that the stars appear stationary in the animated sequence, but the Moon moves further to the left (East) in each of the image relative to the stars.  In the final frame the Moon has totally covered one of the two stars.  During the 48 minutes of the total eclipse sequence, the Moon has moved about one lunar radius relative to the stars due to its orbital motion around the Earth.

Notice in the third frame the lower star appears right on the limb of the Moon soon to be covered.  This is an example of a lunar occultation in which the Moon blocks the light from a star.  An occultation event can be seen visually through a telescope and timed to the nearest fraction of a second when the star suddenly disappears from view.  A video camera attached to a telescope (modern DSLR camera have very high sensitivity and video recording) can record these events with the precision of a single video frame (1/30 sec).  Amateurs can record these events and contribute timings to the International Occultation Timing Association (IOTA https://occultations.org/  Timing events are important to map small changes and evolution of the lunar orbit throughout time.

There was a total lunar eclipse before dawn this past Tuesday am (November 8, 2022) which I totally missed due to a preponderance of many other projects.  I welcome any photos or discussions of the appearance of the Moon from any readers who have seen the Nov. 8 eclipse.

======================================================================

  Physics Photo of the Week is published weekly during the academic year on Fridays by the Warren Wilson College Physics Department. These photos feature interesting phenomena in the world around us.  Students, faculty, and others are invited to submit digital (or film) photographs for publication and explanation. Atmospheric phenomena are especially welcome. Please send any photos to dcollins@warren-wilson.edu.

All photos and discussions are copyright by Donald Collins or by the person credited for the photo and/or discussion.  These photos and discussions may be used for private individual use or educational use.  Any commercial use without written permission of the photoprovider is forbidden.

Observers are invited to submit digital photos to:

 

Comments

Post a Comment

Popular posts from this blog

Special Physics Photo of the Week

Image
Totality! April 8, 2024 - Photo by Donald F. Collins We traveled to Shaker Heights, Ohio (next to Cleveland) to capture the total solar eclipse.  We woke up to some rain and solid clouds as a cold front passed through, but the front passed with beautiful clear skies by noon.  The totality began about 3:13 pm and lasted 3 min:49 sec. The total solar eclipse is characterized by the corona - the halo immediately surrounding the Sun.  The corona consists of ionized gases ejected from the surface of the Sun which glow with the spectra characteristic of the the elements in the Sun.  The shape of the corona is variable from eclipse to eclipse causing every solar eclipse to produce a different display.  The corona is also strongly shaped by the strong magnetic fields surrounding the Sun.  The eclipse also shows several solar prominences - the flame-like ejections of solar mater being "boiled" off into space.  The prominence protruding from the south limb (the bottom edge of the pho
Read more

Physics Photo of the Week

Image
Physics Photo of the Week November 17, 2023 Brilliant Rainbow - Photos and diagrams by Donald F. Collins This brilliant rainbow was seen several weeks ago (October 20, 2023).  The rain that day (0.10 inch) was the final rain before the onset of a severe drought - not relieved until a light rainfall over three weeks later (0.21 inch) on November 11. Rainbows appear only when both rain and sunlight are present at the same time.  The rain drops must be illuminated directly by the sunlight for the rainbow to be visible.  In this image the rainbow appears to be between Warren Wilson College (near the foot of the rainbow) and the mountains behind the base of the rainbow.  Both the foreground, where a building of WWC is visible and the immediate background mountains as well as the rain are all lit up by direct sunshine. The picture at right shows a zoomed-in photo of the base of the rainbow.  The colors are extremely brilliant!  All the colors from red to blue are shown in this photo.  Notice
Read more

Physics Photo of the Week

Image
Physics Photo of the Week March 8, 2024 The Sun I photographe d this image of the Sun recently (Feb 26, 2024) using a 4-inch (104 mm aperture) telescope fitted with a special solar filter and a digital SLR camera.  The solar filter has a transmission of 1/100,000 amount of the incident light.  The solar filter also reddens the image.  Since the Sun's surface, or photosphere , has a temperature of about 5700 deg K, its true color is blue white - about the color of old-fashioned fluorescent light tubes. Notice the large sunspot dominating a group of sunspots on the center right of the Sun's image.  The Earth is only about 1/100 the diameter of the Sun, smaller than the size of the large sunspot.  Sunspots are cooler regions of the Sun's surface (about 2000 deg K cooler than the surrounding photosphere).  Sunspots are also known for strong magnetic fields directed out of the sunspots.  Thus a sunspot  resembles the north pole or south pole of a strong magnet.  This strong magn
Read more