Wednesday, November 8, 2017

Aurora Week



   Last night an uptick in geomagnetic activity resulted in a modest, moonlight hampered northern lights show.  I left for work early and set my camera up to run all night and immediately caught a couple of faint pillars of light.
Aurora Pillars

  Within the hour, as I went about my assigned tasks the intensity picked up to encompass the entire northern horizon.


     Last nights display neatly fits into the pattern of my previous aurora observations.   The first time that I saw the Northern Lights was coincidentally 26 years ago to the day on November 8, 1991. Over the years I've seen them 11 times from the state of Michigan.

 Here is a list of those dates.
November 8, 1991
November 5-6, 2001
October 29, 2003
November 20, 2003
November 7-8, 2004
November 10, 2004
March 17, 2015
November 4, 2015
September 29, 2016
September 28, 2017
And last night November 7-8, 2017.

  What jumps out from the list is that 73% of the sightings occurred over 6% of the calendar that spans from October 29 to November 23.  An even tighter window from November 4 to November 10 includes 55% of my observations in a 7 day period.  The Northern Lights are more likely to occur in the spring and fall rather than summer and winter for reasons explained in the link below.
NASA explanation 

    The most frequent cause of an auroral display is increased activity on the Sun that results in a coronal mass ejections that releases charged particles toward the Earth.  But as can be seen in the photo below, the spotless Solar disk indicates minimal activity, as we are currently heading toward the end of the current 11 year solar cycle.  
  The cause of last night's (as well as September 28th's) northern lights was a hole in the solar atmosphere that released a stream of Earth-directed charged particles.

   After the aurora died down my camera captured the International Space Station as it zipped across the northern sky at 6:20 AM.

Sunday, October 22, 2017

Orionid Meteor Shower 10/22/2017

  Last night after a 4 hour drive across the state, I stepped out on to the back deck to give a listen for owls.  With temperatures lingering in the mid-60's I decided to pull up a chair and crack open a beer and put some real effort into owling.  After a few minutes as I was staring at the clear moonless sky, I remembered that the Orionid Meteor shower was near its modest 20/hour peak.  So I grabbed the camera, cable release and tripod to do some serious multi-tasking. 

    The meteor in the above photos was a sporadic rather than an Orionid.  Its direction of travel would have been from the lower right corner of the frame had it been an Orionid.

  This one was a Orionid (I rotated and cropped the photo for composition's sake).
A burning grain of dust cast off of Comet Halley
 

Thursday, September 28, 2017

Northern Lights 9/28/2017


  Although the Sun is quickly approaching the minimum activity portion of its 11 year cycle, it still can send streams of particles that interact with Earth's magnetic field.  Last night that interaction produced a respectable auroral display for the mid-latitude areas of the US.  The problem that I had to deal with was a persistent layer of low level clouds that didn't dissipate as promised.  Despite less than favorable conditions I set my camera up at work and let it take 6-second long exposures all night long.  The photo above was taken during the peak of the activity around 3:30 AM.

Thursday, August 24, 2017

Black Hole Sun


    In the two days that I spent in Eastern Oregon leading up to Monday's total eclipse, I asked a few locals where they intended to view the eclipse.  I was kind of surprised that some of them planned to view from their homes just outside of the path of totality.  Although 99.7% rounds up to 100%  and that is adequate in most situations, it doesn't compare when it comes to eclipses.
99.7%
    When 99.7% of the Sun is covered you're still looking at the Sun.  When 100% of the Sun is covered you're able to see the elusive corona and prominences the filaments of particles attempting to escape the solar surface.
100%
     The eclipsed Sun is comparable in brightness to a Full Moon.
    During the 1 minute 56 seconds of totality I was frantically operating and adjusting 2 cameras, one with a 500mm lens and the other wide angle 28mm lens.  During the fleeting moment of the 'diamond-ring' effect as the last (first) ray of sunlight disappears (appears)  at the beginning (end) of totality, the Sun and Moon combination looks like a ring of corona with one bright point shining like a diamond. At those opportunities I should have been manning the telephoto equipped camera, Instead I only (accidentally) caught it with the wide field camera.
  Crop of photo above shows a diffraction obscured 'Diamond-ring' effect.
     A little longer exposure shows the sparsely illuminated foreground during totality.
   A crop of that photo shows the star Regulus to the lower left of the eclipse. Click on photo below to see it.

   Another neat effect observable during the partial phases before and after totality is that light passing through a small aperture reveals an image of the light source.  Among our group of eclipse watchers was my niece Danielle who's sunhat projected a multitude of mini eclipses on her shoulder. 

Monday, August 21, 2017

Total Eclipse 8/21/2017

    Disclaimer : These photos do no justice to the spectacle created by the Moon blotting out the late morning Sun.

  It started innocently enough as a small notch formed on the upper right edge of the Sun.

   The bite got bigger....

....until our local star showed a fat crescent.

   It progress until only a sliver remained
    After the last ray of sun shined through a deep crater on the Moon's rim creating a diamond ring effect(not pictured), the elusive solar corona appeared.  A close look at the photo below reveals a red promenience at the same position that the moon's transit started.
  A longer exposure shows the star Regulus (circled) to the lower left of the eclipsed Sun.

He had to stay home because he couldn't pass the eclipse safety test.

Friday, August 11, 2017

Perseid Meteor Shower 8/11/2017

   This year's Perseid Meteor Shower is set to peak over the next two nights.  Although the peak rate of 60/hour is spread out over the wee hours of Saturday and Sunday  much lower rates can be detected over a period of 3 weeks surrounding this weekend.
    At 2:00 this morning I set up my camera on the back deck and shot over 700 consecutive 5-second long exposures with the hopes of catching the inhilation of a sand-grain sized particles cast off of periodic Comet Swift-Tuttle.

Got it.
  This year's shower is hampered by the recently full moon whose illumination decreases contrast between the meteors and the background sky. When the above photo was taken the Moon was 3.5 days past full shining at -11 magnitude with an 87% lit disk.   The photo below shows the moonlight encroaching from the right side of the frame.
Full frame of above photo
   
    Meteors weren't the only things zipping by.  Also in the sky were........

Jet  with its flashing beacon


Satellite

Andromeda Galaxy encircled
   Late in the observing session my camera caught a second Perseid in the same field of view as the 2 million lightyear distant Andromeda Galaxy,


Wednesday, March 22, 2017

Venus Update 3/22/2017

   This morning Venus rose 33 minutes before the Sun and I was able to get some photos of its 1.4% illuminated crescent 3 degrees above the horizon. The separation between it and the Sun is now down to 9.7 degrees.

   In the enlarged image inset in this photograph I think that I can see the whole planetary disk not just the sunlit part.