Physics Photo of the Week

Physics Photo of the Week March 22, 2024   M42 - The Great Nebula in Orion - Astrophotos by College View Observatory The Orion Nebula - Messier 42 - is the brightest nebulous object in the sky - even visible with the naked eye in dark skies.  If this looks like a large cosmic cloud lit up from the inside - that's exactly what it is!  This cloud is in the Milky Way galaxy - "only" about 1300 light years distant.  This nebula is relatively close.  The closest external galaxy is about 2 Million light years distant - over 1000 times further away.  The colors and the large angular size (greater than one degree) make the Orion Nebula one of the most beautiful and interesting cosmic objects! The interior light for illuminating this gigantic cosmic cloud is a nursery of "baby" stars in the middle of it.  However the "baby" stars are not "innocent".  They are some of the hottest stars known in the cosmos as well as some of the largest.* The photo at

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

Clouds and Sunshine on Groundhog Day Photos by Donald Collins  On Groundhog Day (Feb. 2, 2024) we had nice, sunny weather with a few clouds.  The groundhog must have seen his shadow because we have had continuing cold temperatures - but no snow - for the beginning of the second half of the season.  Groundhog Day historically was chosen to occur approximately halfway between the winter solstice and the spring equinox. I had been examining the weather satellite photos (from https://weather.ndc.nasa.gov/GOES/ ) and noticed the wave-like clouds in the area northeast of my location near Warren Wilson College - the 'X' in the image (right) in western North Carolina.  These wave clouds are quite fascinating, so I grabbed my camera and looked from my deck in the direction of the clouds northeast of our house to photograph the Groundhog Day clouds in the top photo. Since clouds are dynamic - always moving - cloud photos are much more interesting if we take time-lapse photos (one photo

  February 9, 2024 The Owl Nebula - and other planetary nebulae Photos by Donald Collins - College View Observatory   If we look with a telescope with some skill we can view the Warren Wilson College's mascot looking down on us.  The Owl Nebula is a class of nebulae that are called " Planetary Nebulae ".  Planetary nebulae are the remnants of dying stars.  A star like our Sun, when its hydrogen fuel is used up by fusing into helium, the resulting lack of internal radiation pressure allows the star to shrink by its self-gravity.  However, while shrinking, the core of the star becomes dense enough and hot enough for helium gas to ignite from nuclear fusion to form even heavier elements (carbon, oxygen,etc).  This second ignition blows away the outer portions of the progenitor star into an expanding cloud that we can see with telescopes. Planetary nebulae have nothing to do with planets.  The name originates because primitive telescopes revealed these objects to

  January 26, 2024        "Rimey" Craggy s     A recent cold weather weekend (Jan 19-21, 2024) had temperatures at Warren Wilson College dip into the single digits.  January 19 was cloudy and snowy all day although very little accumulation occurred.  Clear weather on Saturday, January 20 revealed the Great Craggy Mountains that overlook Warren Wilson College were coated with rime ice from the overnight winter storm. The center of the upper photo is enlarged in the photo at right.  The distant tops of the Craggy Mountains were coated in the white rime ice that clings to the tree tops.  At lower elevations, the tree tops are bare and we see snow deposited on the ground.  Rime ice is an interesting winter formation that we experience in the mountains in winter weather.  Rime occurs when clouds exist at below freezing temperatures.  In such clouds, the cloud particles are liquid water micro drops that remain liquid.  The water droplets are super-cooled.  That is they remain liqu

December 8, 2023 M13 - A Globular Cluster - Photos by Don Collins - College View Observatory There are about 100 of these large clusters of stars orbiting the Milky Way Galaxy.  Similar clusters are found in other galaxies.  These assemblages of stars contain several hundred thousand stars and up to a million stars.  These clusters are also very old - about 10 billion years - older than the Sun and the Solar System.  Unlike open clusters (such as the Pleiades or "Seven Sisters") the globular clusters have so many stars that they are gravitationally stable.  All the stars are whizzing around a common center of mass in random orbits similar to a swarm of insects.  This globular cluster is about 20,000 light years from Earth and about 140 light years in diameter.   If our Solar System were in the midst of this cluster of close to 1 million stars, the sky would be ablaze with starlight!  However, in spite of the incredible age of the cluster, a Solar System would probably not la