Physics Photo of the Week

Physics Photo of the Week January 30, 2023 Update on Comet C/2022 E3 (ZTF) Photos by Donald Collins                   The comet featured on Jan 20 PPOW has become brighter.  The photo above was taken on January 27, 2023 using a DSLR color camera mounted on a tripod.  The dusty tail appears greenish due to the sunlight scattering off the small dust particles that are blown away from the comet. The comet was still not visible to the naked eye, but a time exposure with a normal lens on a DSLR camera barely shows the comet.  The image on the right shows a wide-angle photo of the Big Dipper on the right side of the photo.  The pointer stars point to Polaris, the North Star.   The comet last Friday was in the location of the circle, but barely visible in the photo. The original wide-angle image above was zoomed in by cropping with the computer and shown at left.  This clearly shows the comet that resembles a fuzzy...

  Comet C/2022 E3 ZTF Photo by Donald Collins, College View Observatory For almost a year astronomers have been anticipating the arrival of a "major" comet in January and February of 2023.  The discovery of this comet was made by the Zwicky Transient Facility (ZTF) in March 2022. (Bob King, Sky and Telescope, January 2023)  Observations of position over the course of several weeks have enabled astronomers to calculate the precise parameters for the orbit (inclination, period, eccentricity, etc).   Anyone can download the parameters and load into a sky-viewing and telescope guiding program to direct a telescope to point to it. I made this photo the night of January 12, 2023 with the College View Observatory 14 inch telescope and CCD camera.  This photo consisted of stacking about 10 digital images of 60 seconds each.  Compared with the stars, the comet is quite bright, but we can see stars through the dusty tail.  The illumination of the comet is ...

Physics Photo of the Week December 23, 2022 The Christmas Tree Nebula - Photo by Donald Collins with the College View Observatory Merry Christmas Everyone! The Christmas Tree Nebula, part of NGC 2264 consists of a cosmic cloud composed of dust and hydrogen in the constellation Monosoros - just east of Orion.  This gas/dust cloud is a busy center of extensive star formation.  The dust and hydrogen gas have been contracting due to their own self-gravity and clumps become extremely dense and begin to form new stars in the centers of the dust cloud.  Like the nearby Orion Nebula ( PPOW for February 8, 2019 ), this nebula is a stellar nursery where hot, giant, blue stars are "born".  The Christmas Tree cloud resembles a dust "pillar", which is also seen in the Orion Nebula as a dark shadow.  The bright halo surrounding the Christmas Tree cloud is a massive cloud of hydrogen that glows red and emits the red glow characteristic of a hydrogen lamp - a glass tube filled ...

Physics Photo of the Week        December 9, 2022 Slinky Defies Gravity My grandson Jay is holding a yellow plastic "Slinky" at one end is about to drop it.  We recorded a slow-motion video for the falling slinky.  When you watch the video (see link below) be sure to pay attention to the bottom of the yellow slinky - it seems to defy gravity and doesn't fall until the rest of the slinky "catches" it and the collapsed slinky continues is descent to the floor.  Shouldn't the whole slinky fall at once?  The bottom edge of the stretched-out slinky simply "floats" at the level just below Jay's knee while the top of the slinky falls due to gravity.    Press this link to see the slow motion video. Why does the base of the slinky remain suspended motionless while the top of the spring falls rapidly?  Shouldn't the whole stretched out slinky fall at once? The answer lies in the fact that gravity is not the only force acting on each of t...

  Slow Motion Video

  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...

  Physics Photo of the Week October 21, 2022 First Rime Ice - Fall 2022 This Wednesday morning (October 19, 2022) brought the first rime ice deposit on the Great Craggy Mountains overlooking Warren Wilson College in the midst of fall colors.  This is a sign that winter is about to descend. The whiteness on top of Craggy Gardens, which I call "Craggy", is due to the frost on the twigs and remaining leaves on the trees of the mountaintop at high elevations (higher than 5000 ft above sea-level).  What looks like frost from a distance, is frozen cloud droplets, that were below the freezing point while within a descended cloud.  The cloud droplets were super-cooled below the freezing point of water (32 deg F).  As soon as the droplets collided with a leaf or twig, they were stimulated to freeze immediately because the twigs and leaves provided nucleation sites to attract the crystallizing super-cooled water. A much more vivid color photo was made the last time Physic...