June Moon at Ascending Node and a Solar Eclipse

   Sunday June 21st the new Moon will be crossing the plane of the ecliptic moving north. This is known as the ascending node, one of two intersections the Moon’s orbital path has with the ecliptic. The ecliptic is actually the Earth’s orbit, and the Moon’s orbit is inclined about 6o from the ecliptic. So there are two node intersections, the ascending and descending nodes.
   Whenever our Moon at either new or full phase crosses the plane of the ecliptic, a node crossing, there will be an eclipse of the Sun with a new Moon, or a lunar eclipse with the full Moon phase. On the 21st the new Moon will be aligned with the Sun for a solar eclipse. (Not visible from North America) However this solar eclipse is an annular solar eclipse, where at mid-eclipse the Moon does not completely cover the Sun. There is no ‘diamond bead’ effect, no corona like what is seen with a total solar eclipse. This is because the Moon and our Sun appear to be about the same size in the sky with the exception that the Moon’s orbit is more elliptical than the Earth’s orbit around the Sun. This means that the Moon can be closer or further away during a solar eclipse. With this annular solar eclipse the Moon is further away, appears smaller than the Sun, and at mid-eclipse leaves an annulus, a ‘ring of fire’ around the Sun as this animated graphic is showing.
Note, I have brightened the side of the Moon facing toward us. During a solar eclipse we would only see a silhouette of the Moon.

   Does our Moon actually go around the Earth as many graphics show? From our perspective on the Earth the Moon appears to circle around the Earth. However, in reality, the Moon orbits the Sun together with the Earth*
*Click here to read my 2006 Scope on the Sky column “The Real Shape of the Moon’s Orbit”. (PDF)


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March Moon at Apogee

   Our Moon reaches apogee, (greatest distance from Earth), for this orbit, on Tuesday March 24th. At that time the new Moon will be at a distance of 31.88 Earth diameters 252,712 miles (406,700 km) from the Earth.

   This is the greatest apogee distance, and smallest appearing (if you could see it) for our Moon this year. In other words this new Moon is a ‘Super-Mini Moon’!

   On the day of the apogee Moon the Moon is at new Moon phase so it rises with the Sun and sets with the Sun. Start watching for the waxing crescent Moon in the evening skies at sunset in a day or so.

   However there are four of the six naked-eye visible planets over the east-southeastern horizon before the Sun and new Moon rise.

   Does our Moon actually go around the Earth as this graphic shows? From our perspective on the Earth the Moon appears to circle around the Earth. However, in reality, the Moon orbits the Sun together with the Earth*

   *Click here to read my 2006 Scope on the Sky column “The Real Shape of the Moon’s Orbit”. (PDF)

   
   
   
   
   
   
   
   
   

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December Moon at Descending Node and an Eclipse

   Thursday December 26th the Moon, at new Moon phase, crosses the plane of the ecliptic moving south. This is known as the descending node, one of two intersections the Moon’s orbital path (dark green line) has with the ecliptic.
   What happens when the Moon is at new phase and is also at a node crossing? You get an eclipse of the Sun, which in this instance will be an Annular Solar Eclipse. This is a solar eclipse however the Moon is far enough from the Earth that it appears to be smaller than the Sun. So, unlike with a Solar Eclipse where at mid-eclipse the Moon’s disk covers the Sun’s disk, during mid-annularity the Moon’s disk does not completely cover the disk of the Sun but instead leaves a ‘ring of fire’ known as the annulus around the Sun.

This eclipse will be visible from Saudi Arabia to south of the Philippine Islands.

Note: The picture I used for the banner is of the 2011 Annular Eclipse and it is from the NASA Hinode satellite. Also at the NASA web page the link takes you to is a video of the Annular Solar Eclipse as seen from the satellite in Earth orbit.


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A Black Moon

   What is a “Black Moon”? According to a commonly used definition a “Black Moon” is any month during which there are 2 new Moons, or even more rare a month with no new Moons. Obviously the Moon at new phase is in the direction of the Sun and therefore is not visible at all, perhaps given rise to the name “Black Moon” because the illuminated side of the Moon is toward the Sun, and the unilluminated, dark, side of the Moon is toward the Earth.
   On Thursday August 1st the first of two new Moons this month will rise about 30 minutes after the Sun rises and will not be visible as it follows the Sun across the sky to moonset about 1 hour after sunset local time. On August 30th the second new Moon of the month will follow a similar pattern as the new Moon on August 1st in that this new Moon also will not be visible as it too follows the Sun, setting within an hour after the Sun sets. Graphics below are set for the time when the new Moon transits, or is due south, and is mid-way between rising and setting.
   What makes the term “Black Moon”, in this instance, interesting is that depending on your time zone the “Black Moon” may have been either July or August depending on your local time zone for the new Moon of July 31st or August 1st.

 
New Moon Dates and Times (using UT)
July 2          19:16 UT
August 1         3:12 UT  (July 31 10:12 pm CDT)
August 30       10:37 UT


   
   
   

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Circumstances for a Solar Eclipse


   Friday July 13th and Saturday the 14th circumstances are such that there will be a partial solar eclipse that will be best viewed from along the northern coast of Antarctica. (hey! every Antarctic coast is a northern coast!!
Specifically the partial solar eclipse will be visible at around 129o E near the Claire Coast.

   Circumstances for a solar eclipse, like for a lunar eclipse, require the Moon to be at either its ascending node or its descending node and be at or close to either new or full Moon phase. A node crossing occurs when the Moon with an orbit tilted 6o from the ecliptic (the Earth’s orbit) intersects the ecliptic.


   The Moon has an elliptically shaped orbit so if the timing for lunar apogee (furthest from Earth) or perigee (closest to the Earth) happens around a new Moon at a node crossing then the apparent size of the Moon will be anywhere from smaller to larger than the Sun’s apparent size. Smaller means a longer eclipse including the length of totality.


   
   
   However the bottom line is the timing between the node crossing and new Moon. This time the Moon crosses the ecliptic moving north, ascending node, approximately 24 hours after new Moon phase setting up a partial solar eclipse.

So what are the circumstances?
Times are in Universal Time (CDT = UT-5)
   July 13th
   1:48 UT – Partial Solar Eclipse Begins
   2:48 UT – New Moon — Partial Solar Eclipse
   3:01 UT – Mid-Eclipse (maximum Sun covered)
   4:13 UT – Partial Solar Eclipse Ends
   8:27 UT – Moon at Perigee – 357, 432 km (222,098 miles)
   July 14th
   2:52 UT – Moon at Ascending Node

   
   
   

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Solar Eclipse Follow-Up

   Fearing for massive traffic jams we (wife Susan and granddaughter Keeley) left for Briarcliff Elementary School in North Kansas City around 8 am. Virtually no traffic as we went around the city and went across the Missouri River and river valley on Highway 169 and then up the bluff on the other side to the school. Lightning was to the north and southwest and thunder was rumbling – but the Sun was sort of shining through broken clouds.

   The sky remained partly cloudy as I set up and students were coming outside to practice how to use their eclipse glasses. The sky stayed partly cloudy until about 10 minutes before totality as the leading edge of what would soon be rain approached from the northwest as broken cumulus type clouds.

   Leading up to totality there were two distinct sunspot groups visible as this picture shows. We were fortunate that the sky stayed relatively clear leading up to totality. However the broken clouds started clumping together but the clouds did part several times allowing for us to see totality each time there was a break in the clouds.
   No post totality pictures because within a few seconds after totality ended the last of the broken clouds passed and the sky was completely overcast. As we left the school it was raining. Got home a few minutes before the eclipse ended – skies were partly cloudy – so we had one last look with eclipse glasses.


   A big shout-out to Mrs. Kate Place, her staff and students, at Briarcliff Elementary School for hosting the Eclipse on the Cliff event.
   Click here to see 360o pictures and videos. Be sure to select HD at the highest resolution possible.
   
   
   

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Click here to go to the Qué tal in the Current Skies web site for monthly observing information, or here to return to bobs-spaces.

Solar Eclipse of August 21


   I too have written some information about the solar eclipse, aka “The Great American Eclipse”, of August 21st. It is my attempt to compare two different views of the eclipse. One will be from within the path of totality where I will be, and the other in my hometown of Lee’s Summit Missouri just south of the path of totality by a few miles. As a result residents in Lee’s Summit, unless they drive north, will only see a partial eclipse with 99.986% of the Sun covered.
   So without further ado click here to go to Eclipsed Thoughts.

   
   
   

Click here to go to the Qué tal in the Current Skies web site for monthly observing information, or here to return to bobs-spaces.

February Moon at Descending Node and a Solar Eclipse

26feb-descending-node
   Sunday February 26th the new Moon will be crossing the plane of the ecliptic moving south. This is known as the descending node, one of two intersections the Moon’s orbital path (dark green line) has with the ecliptic. The time for new Moon phase 14:59 UT while the time for the node crossing is 8 hours earlier at 6:40 UT. Given the close times for the two events means that there will be a solar eclipse. However the Moon, because of its elliptical shaped orbit, will be at a further distance from the Earth such that it will appear smaller in diameter than the Sun appears. This means that at mid-eclipse, or totality, the Moon will not completely cover the Sun, instead there will be a ring of sunlight around the Moon. The ring of sunlight is called the annulus and so this is an annular solar eclipse. The eclipse will be visible from parts of southern Argentina and western central Africa.
annular-eclipse-ani   On my birthday in 1994 I was ‘honored’ to not only have an annular solar eclipse on that day but the eclipse path, the path of annularity, crossed right over where I live southeast of Kansas City Missouri. This animation is of the May 10th annular solar eclipse.

   
   
   

Click here to go to the Qué tal in the Current Skies web site for monthly observing information, or here to go to bobs-spaces.

September Moon At Ascending Node #1

1sep-ascending-node   Thursday September 1st the new Moon will be crossing the plane of the ecliptic moving north relative to the ecliptic. This is known as the ascending node, one of two intersections the Moon’s orbital path has with the ecliptic. The ecliptic is actually the Earth’s orbit and the Moon’s orbit is inclined about 6o from the ecliptic. So there are two node intersections, the ascending and descending nodes.

   Coincidentally the new Moon and the Sun will also be together for an annular solar eclipse.

   Does our Moon actually go around the Earth as many graphics show? From our perspective on the Earth the Moon appears to circle around the Earth. However, in reality, the Moon orbits the Sun together with the Earth*

*Click here to read my 2006 Scope on the Sky column “The Real Shape of the Moon’s Orbit”. (PDF)

Read this very informative article about the Earth-Moon system and their orbital motions, written by Joe Hanson. “Do We Orbit the Moon?”

   
   
   

Click here to go to the Qué tal in the Current Skies web site for monthly observing information, or here to go to bobs-spaces.

September Annular Eclipse

node-close_up   The solar eclipse on Thursday September 1st, will have been brought to us by the nodes. No the nodes are not a scientific nor a musical group, but rather the nodes represent an intersection between the orbital path of our Moon, or another planet, with the Earth’s orbital path, the plane of the ecliptic.
   There are two nodes or intersections, the ascending node and the descending node. There are two nodes because the planets as well as our Moon do not orbit the Sun on the same level, or plane as does the Earth. Their respective orbits are inclined (tilted) away from the plane of the ecliptic by varying amounts such that they will at times appear below or above the plane of the ecliptic. There will be two times each orbit around the Sun where the planet or our Moon will be on the plane of the ecliptic as it crosses moving from below setting up the ascending node or from above toward below, setting up the descending node.
   So what is the significance of the nodes? The significance is all about timing. If the time of the new Moon phase, for example, occurs at or near the time for a node crossing then there will be a solar eclipse. Remember that at this moment the Moon is on the plane of the ecliptic and is more or less directly between the Earth and the Sun. More importantly, if the times are exact or very close there will be either a total solar eclipse or an annular solar eclipse. 29april-annular_eclipse-ani   During an annular eclipse the Moon is somewhere near its apogee, or most distant point for that particular orbit. This annular eclipse happens 5 days before the Moon reaches apogee on September 6th but the Moon is still far enough away so that its apparent diameter is less than the Sun’s apparent diameter. Both are around 0.5o or 30′ in apparent diameter, however for this annular eclipse the Moon will be about 3% smaller and not be able to completely cover the Sun at mid-eclipse. Instead at mid-eclipse there will be a ‘ring of fire’, the annulus, around the Moon.
   Thursday September 1st the new Moon phase is at 9:03 UT and the Moon is at its ascending node about 6 hours later at 15:27 UT. The Moon makes first contact with the Sun at 6:23 UT; maximum or mid-eclipse is at 9:06 UT; and the eclipse officially ends with last contact at 12:00 UT.
   To sort of complete this story, if there is a solar eclipse, no matter how total or less than total, there will be a lunar eclipse two weeks away at full Moon phase. Eclipses occur in pairs so this pair will be completed with the penumbral lunar eclipse at full Moon on September 16th.Moon Grazing the Earths ShadowFull Moon on September 16th is at 19:05 UT, about 19 hours after the Moon is at its descending node, 11:57 UT September 15th. Because of the time difference, the angle the Moon follows through the Earth’s shadows does not cross the dark inner umbral shadow but rather only takes it across the less noticeable outer penumbral shadow. Unless you knew about it you may not notice a slight dimming of the reflected moonlight.

   For an outstanding web site about all eclipses including information for these two eclipses go to the Hermit Eclipse web site.
   
   
   

Click here to go to the Qué tal in the Current Skies web site for monthly observing information, or here to go to bobs-spaces.