“Fire Rainbow” over Keppel Henge but don’t call it that!

The fifth annual solstice celebration was held on Saturday June 21. And for the five years it has been held, we have only been clouded out once. This year as an added attraction what is incorrectly called a “fire rainbow” appeared for an hour or so just as the celebration was coming to an end. Luckily at least two photographers were still on the scene to record the event.

The website
www.atoptics.co.uk/halosim.htm gives all the details about how it forms (hexagonal ice crystal in cirrus clouds are responsible for many halo phenomena) and it gives the more correct term “circumhorizon arc” or if it extends all the way around the sky (rare) it is a “circumhorizon halo”.

It was first noticed just after the pointer shadow passed the base of the summer solstice stone at 1:25 pm (solar noon) and I watched it finally fade away around 2:45 pm or so by the time I got back to Owen Sound.

The term “fire rainbow” is totally incorrect because it is neither a rainbow (which is caused by water droplets) nor on fire but reporters have latched onto the description because it does look like a rainbow on fire. The second image below illustrates that quite nicely. Image taken over Owen Sound June 2004 by yours truly.

There is another halo (arc really) called the circumzenithal arc that appears
above the sun on some occasion, but its colours are reversed. Both the 22° halo and circumhorizon arc have red on the outside of the colour band. The circumzenithal arc's colours are the opposite. So check out the view straight up so you don't miss that one.

One other note is that these arcs occur only when the sun is high in the sky (summer) and there are cirrus (ice) clouds present. With a low sun, you may see the CZA but not the CHA. Solar noon on summer solstice fits the bill nicely.

John H.

Images below by JH June 2014 and June 2004

IMG_87662_324K

Circumhorizon arc_June 2-04-untitled-14_986K

Summer Solstice Coming SOON!

On June 21 (correction!) (Saturday) at 5:51 am, the Sun reaches its Summer Solstice position in the sky for the northern hemisphere. It is effectively at the highest point in our sky around noon (1 pm DST) and from then on starts its descent in elevation for the next six months. The summer officially starts on June 21 and continues until the start of autumn on Sep 23.

Screen shot 2014-06-10 at 5.47.40 PM

Sunrise on Summer Solstice at Stone Henge June 21, 2005



BLUEWATER ASTRONOMICAL and local Tai Chi followers celebrate the event:

Please join BAS at Keppel Henge (Kepplecroft Gardens) for a celebration of the event which will include Tai Chi among the monoliths, a short talk about the significance of Keppel Henge and observing the Sun with solar H-alpha and white light telescopes -all safely fitted with proper filters. The event starts about 11 pm on Saturday June 21. Note that it is customary to contribute a nominal fee ($3 per vehicle is suggested) towards the upkeep of the gardens.

The website for the Keppel Croft gardens is
http://www.keppelcroft.com/
The website for the Henge is here: Keppel Henge
http://www.steveirvine.com/henge.html

The google map address is: 504156 Island View Dr Grey Rd. 1 at Big Bay ph: 519-534-1090 and a map is available there.

The following article is an extract from the Wikipedia article entitled “Solstice”. For the full article click
HERE.

Happy Sun gazing!
John H.



Solstice
A solstice is an astronomical event that occurs twice each year as the Sun reaches its highest or lowest excursion relative to the celestial equator on the celestial sphere. The solstices, together with the equinoxes, are connected with the seasons. In many cultures the solstices mark either the beginning or the midpoint of winter and summer.
The word
solstice is derived from the Latin sol (sun) and sistere (to stand still), because at the solstices, the Sun stands still in declination; that is, the seasonal movement of the Sun's path (as seen from Earth) comes to a stop before reversing direction. At latitudes in the temperate zone, the summer solstice marks the day when the sun appears highest in the sky. However, in the tropics, the sun appears directly overhead (called the subsolar point) some days (or even months) before the solstice and again after the solstice, which means the subsolar point occurs twice each year.
The term
solstice can also be used in a broader sense, as the date (day) when this occurs. The day of the solstice is either the longest day of the year (in summer) or the shortest day of the year (in winter) for any place outside of the tropics.

Relationship to seasons
The seasons occur because the Earth's axis of rotation is not perpendicular to its orbital plane (the “plane of the ecliptic&rdquoWinking but currently makes an angle of about 23.44° (called the "obliquity of the ecliptic"), and because the axis keeps its orientation with respect to an inertial frame of reference. As a consequence, for half the year the Northern Hemisphere is inclined toward the Sun while for the other half year the Southern Hemisphere has this distinction. The two moments when the inclination of Earth's rotational axis has maximum effect are the solstices.
At the
June solstice the subsolar point is further north than any other time: at latitude 23.44° north, known as the Tropic of Cancer. Similarly at the December solstice the subsolar point is further south than any other time: at latitude 23.44° south, known as the Tropic of Capricorn. The subsolar point will cross every latitude between these two extremes exactly twice per year.
Also during the June solstice, places on the
Arctic Circle (latitude 66.56° north) will see the Sun just on the horizon during midnight, and all places north of it will see the Sun above horizon for 24 hours. That is the midnight sun or midsummer-night sun or polar day. On the other hand, places on the Antarctic Circle (latitude 66.56° south) will see the Sun just on the horizon during midday, and all places south of it will not see the Sun above horizon at any time of the day. That is the polar night. During the December Solstice, the effects on both hemispheres are just the opposite. This also allows the polar sea ice to increase its annual growth and temporary extent at a greater level due to lack of direct sunlight.