Moon in 2017

Moon Phases Mosaic

A mosaic made from 9 individual photos of the Moon captures its phases over one synodic month. For complete details about this image, see Moon Phases Mosaic. The individual images included in this composite can be found in the Moon Phases Gallery. For more composites, see Moon Phases Mosaics. Photo copyright 2012 by Fred Espenak.

We tend to take the Moon for granted but it shares a unique history with Earth. Shortly after its formation 4.5 billion years ago, “proto-Earth” collided with a Mars-sized object called Theia. Much of “proto-Earth” and Theia merged to become our Earth, but the impact also ejected a large amount of material into space. Some of it coalesced to become the Moon (see: Giant Impact Hypothesis).

The Moon’s orbit stabilizes the axial tilt of Earth, preventing it from undergoing chaotic variations that would lead to catastrophic changes in climate. And the daily rise and fall of the Moon-induced tides has left an indelible imprint on Earth. Some scientists even argue whether life on Earth would be possible without the influence of the Moon (see: Without the Moon, Would There Be Life on Earth?).

With this big picture in mind, we gain a new appreciation for the Moon as we watch its phases, cycles, and motions during 2017.

As the Moon orbits Earth, its changing geometry with respect to the Sun produces the Moon’s characteristic phases (New Moon, First Quarter, Full Moon and Last Quarter). One orbit of the Moon relative to the Sun (the synodic month) has a mean duration of 29.5306 days (29 days 12 hours 44 minutes).

                   Moon Phases for 2017 (GMT)

   New Moon      First Quarter      Full Moon       Last Quarter
-------------    -------------    -------------    -------------   
                 Jan  5  19:47    Jan 12  11:34    Jan 19  22:14    
Jan 28  00:07    Feb  4  04:19    Feb 11  00:33n   Feb 18  19:33    
Feb 26  14:58A   Mar  5  11:32    Mar 12  14:54    Mar 20  15:58    
Mar 28  02:57    Apr  3  18:39    Apr 11  06:08    Apr 19  09:57    
Apr 26  12:16    May  3  02:47    May 10  21:43    May 19  00:33    
May 25  19:44    Jun  1  12:42    Jun  9  13:10    Jun 17  11:33    
Jun 24  02:31    Jul  1  00:51    Jul  9  04:07    Jul 16  19:26    
Jul 23  09:46    Jul 30  15:23    Aug  7  18:11p   Aug 15  01:15    
Aug 21  18:30T   Aug 29  08:13    Sep  6  07:03    Sep 13  06:25    
Sep 20  05:30    Sep 28  02:54    Oct  5  18:40    Oct 12  12:25    
Oct 19  19:12    Oct 27  22:22    Nov  4  05:23    Nov 10  20:37    
Nov 18  11:42    Nov 26  17:03    Dec  3  15:47    Dec 10  07:51    
Dec 18  06:31    Dec 26  09:20                                        

The table above lists the date and time of the Moon’s phases throughout 2017. The time of each phase is given in Greenwich Mean Time or GMT (a.k.a. Universal Time or UT). A table of the Moon’s phases covering 100 years on AstroPixels.com can be found at Moon’s Phases – 21st Century (GMT). Similar 100-year tables for other time zones include Eastern Standard Time (EST), Central Standard Time (CST), Mountain Standard Time (MST), and Pacific Standard Time (PST). To convert GMT to other time zones, visit Time Zones.

Moonrise on 2015 January 05 from Portal, AZ. Copyright 2015 by Fred Espenak.

What surprises many people is that the length of the synodic month (period from New Moon to New Moon) can vary by more than 6 hours from its mean value of 29.5306 days (29 days 12 hours 44 minutes). The table below gives the date of New Moon, the length of the synodic month, and the difference from the synodic month’s mean value for every synodic month in 2017. For instance, the fifth synodic month of 2017 (beginning May 25) is 5 hours 58 minutes shorter than the mean while the twelfth synodic month (beginning Dec 18) is 7 hours 3 minutes longer than the mean.

                  Synodic Months for 2017 

   Date/Time of          Length of      Difference from
  New Moon (GMT)       Synodic Month      Mean Month 
------------------     -------------     -----------
2017 Jan 28  00:07      29d 14h 51m       +02h 07m
2017 Feb 26  14:58      29d 11h 59m       -00h 45m
2017 Mar 28  02:57      29d 09h 19m       -03h 25m
2017 Apr 26  12:16      29d 07h 28m       -05h 16m
2017 May 25  19:44      29d 06h 46m       -05h 58m   shortest
2017 Jun 24  02:31      29d 07h 15m       -05h 29m
2017 Jul 23  09:46      29d 08h 45m       -03h 59m
2017 Aug 21  18:30      29d 11h 00m       -01h 44m
2017 Sep 20  05:30      29d 13h 42m       +00h 58m
2017 Oct 19  19:12      29d 16h 30m       +03h 46m
2017 Nov 18  11:42      29d 18h 48m       +06h 04m
2017 Dec 18  06:30      29d 19h 47m       +07h 03m   longest

What causes these variations? The explanation involves the Moon’s elliptical orbit and its orientation with respect to the Sun during any given month. If New Moon occurs when the Moon is nearest to Earth (perigee), then the synodic month is shorter than normal. On the other hand, if New Moon occurs when the Moon is farthest from Earth (apogee), then the synodic month is longer than normal. Furthermore, the orientation of the Moon’s ellipse-shaped orbit slowly rotates in space with a period of about 18 years. A more detailed discussion on this topic can be found at Moon’s Orbit and the Synodic Month (EclipseWise.com). You can also find the duration of every synodic month this century at Length of the Synodic Month: 2001 to 2100 (AstroPixels.com).

The time it takes for the Moon to orbit once with respect to its perigee is known as the anomalistic month. Its average length is 27.55455 days (27 days 13 hours 19 minutes), which is nearly 2 days less than the synodic month. The actual length can vary by several days due to the gravitaional effects of the Sun on the Moon’s elliptical orbit. The table below gives the date and time of every perigee and apogee of the Moon during 2017. The Moon’s distance (in kilometers) is also given. The ‘m’ or ‘M’ appearing next to a date indicates the minimum or maximum distance, respectively, for the year. A table listing details of every perigee and apogee this century can be found at Perigee and Apogee: 2001 to 2100 (AstroPixels.com)

                  Perigee & Apogee for 2017 
                  
Date/Time of   Distance       Date/Time of   Distance
Perigee (GMT)    (km)         Apogee (GMT)     (km)
-------------   ------        -------------   ------
Jan 10  06:07   363242        Jan 22  00:14   404913       
Feb 06  13:59   368817        Feb 18  21:14   404376       
Mar 03  07:24   369065        Mar 18  17:25   404651       
Mar 30  12:39   363855        Apr 15  10:05   405478       
Apr 27  16:18   359325        May 12  19:51   406212       
May 26  01:23   357210 m      Jun 08  22:21   406402       
Jun 23  10:49   357938        Jul 06  04:27   405934       
Jul 21  17:09   361238        Aug 02  17:55   405026       
Aug 18  13:14   366129        Aug 30  11:25   404307 m     
Sep 13  16:04   369856 M      Sep 27  06:49   404342       
Oct 09  05:51   366858        Oct 25  02:25   405151       
Nov 06  00:09   361438        Nov 21  18:52   406132       
Dec 04  08:42   357496        Dec 19  01:27   406605 M     

Because the Moon orbits Earth in about 29.5 days with respect to the Sun, its daily motion against the background stars and constellations is quite rapid, averaging 12.2° per day. A table giving the Moon’s daily celestial coordinates throughout the year can be found at Moon Ephemeris for 2017 (AstroPixels.com). This table lists many other details about the Moon including its daily distance, apparent size, libration, phase age (days since New Moon) and the phase illumination fraction.

The most recent Perigean Full Moon (Full Moon near Perigee or closest point to Earth) took place on Dec. 13, 2016. The media loves to call this a “Super Moon” but I prefer to call it the less sensational “Perigean Full Moon” or “Full Moon near perigee”. Whatever you call it, it’s a chance to take a moment and marvel at our beautiful natural satellite. The photo below was taken from my driveway in Portal, AZ as the Moon rose above the Peloncillo Mountains of New Mexico. I was hoping for a completely clear sky but the clouds actually added an appealing element to the scene. Copyright 2016 by Fred Espenak.

When a Full Moon occurs within 90% of the Moon’s closest approach to Earth in a given orbit, it is called a Perigean Full Moon or more commonly a Super Moon. The Full Moon then appears especially big and bright because it subtends its largest apparent diameter as seen from Earth. The table below lists the Perigean Full Moons (Super Moons) occurring in 2017.

  Perigean Full Moons (Super Moons) for 2017

   Full Moon     Distance  Diameter  Relative
    (GMT)          (km)    (arc-min) Distance

Jan 12  11:34     366880     32.57    0.913
Nov 04  05:23     364004     32.83    0.941
Dec 03  15:47     357987     33.38    0.990   closest

The Relative Distance listed in the Super Moon table expresses the Moon’s distance as a fraction between apogee (0.0) and perigee (1.0). For more information on Super Moons and a complete list of them for this century, see Full Moon at Perigee (Super Moon): 2001 to 2100 (AstroPixels.com).

Besides its obvious phases, the Moon also undergoes some additional extremes in its orbit including: Perigee and Apogee, Ascending/Descending Nodes, and Lunar Standstills. Each of these AstroPixels links covers lunar phenomena for the entire 21st Century.

Moon Phases Mosaic

As the Moon orbits Earth, its changing geometry with respect to the Sun produces the characteristic phases. This composite image is a mosaic made from 25 individual photos of the Moon and illustrates its phases over one synodic month. For complete details about this image, see Moon Phases Mosaic. The individual images included in this composite can be found in the Moon Phases Gallery. For more composites, see Moon Phases Mosaics. Photo copyright 2012 by Fred Espenak.

One of the first projects I tackled upon completing Bifrost Observatory in 2010 was to photograph the Moon’s phases every day for a complete month. Of course, the weather doesn’t always cooperate (even from sunny Arizona) so it actually took several months to complete the project. You can see the results at the Moon Phases Gallery. Clicking on any of the thumbnail pictures will give you an enlarged image with complete technical details. You can also visit Moon Phases Mosaics to see composites showing the Moon’s phases over a complete synodic month.

The NASA/Goddard Scientific Visualization Studio has used image data from the Lunar Reconnaissance Orbiter (LRO) mission to create clever animations of the Moon’s ever changing phases and librations in 2017. The example below illustrates the Moon’s phase and libration at hourly intervals throughout 2017, as viewed from the northern hemisphere. Each frame represents one hour.

And not to be accused of northern hemisphere chauvinism, here is a version as seen from the southern hemisphere.

Besides presenting the Moon’s phase and apparent size, these videos show the Moon’s orbital position, sub-Earth and subsolar points, distance from the Earth at true scale, and labels of craters near the terminator. As the Moon orbits Earth, it appears to wobble and tip on its axis. This motion is called libration and it allows us to see about 59% of the Moon’s surface (see Libration (EarthSky)). The major cause of libration is due to our changing line of sight because of the Moon’s elliptical orbit.

Ernie Wright of the NASA Scientific Visualization Studio has also used LRO data to create a web tool called Dial-A-Moon. Enter the month, day and hour and Dial-A-Moon will generate a visualization of the Moon showing the correct phase and libration for that instant during 2017 (see Moon Phase and Libration, 2017).

Finally, what discussion of the Moon would be complete without mentioning eclipses in 2017? There are two eclipses of the Moon. The first is a deep penumbral eclipse on February 11, which is visible from both the Eastern and Western Hemispheres. Penumbral eclipses are rather subtle events and often transpire without any notice (see: Visual Appearance of Penumbral Lunar Eclipses). The second lunar eclipse is partial on August 7 and is visible from the Eastern Hemisphere.

There are also two solar eclipses in 2017. The first is an annular eclipse on February 26. The annular phase of the eclipse is visible from Chile, Argentina, the south Atlantic, Angola, Democratic Republic of the Congo, and Zambia.

The total solar eclipse of August 21, 2017 is the first total eclipse visible from the continental USA since 1979. For more information see the special EclipseWise web page on the 2017 eclipse.

The total solar eclipse of August 21, 2017 is the first total eclipse visible from the continental USA since 1979. For more information see the special EclipseWise web page on the 2017 eclipse.

The second solar eclipse of the year is the long awaited Great American Total Solar Eclipse on August 21. This is the first total solar eclipse visible from the continental USA in 38 years. For complete details on this highly anticipated event, see: 2017 Total Solar Eclipse (EclipseWise.com).

For more details on all these events, see Eclipses During 2017 (EclipseWise.com).

Moonset: Crescent Moon & Earthshine from Portal, AZ. Copyright 2015 by Fred Espenak.

For those who are new to Moon watching, many are surprised that the entire Moon can often be seen during the crescent phase. The pale glow illuminating the unlit part of a crescent Moon is light reflected from Earth and it’s called earthshine. The time-lapse movie above captures earthshine during moonset back one evening in May 2015. Read more about earthshine in this Earth&Sky article.

Watching the Moon’s phases wax and wane as well as the occasional lunar eclipse can best be enjoyed with the naked eye and binoculars. And you don’t even need a dark sky since the Moon is easily visible from the heart of brightly lit cities.

The Moon phases and lunar phenomena discussed here were all generated with computer programs I’ve written (THINK Pascal and FORTRAN 90 running on a Macintosh G4 and MacBook Pro) using Astronomical Algorithms (Jean Meeus).

Fred Espenak


Moon in 2016

Moon Phases Mosaic

As the Moon orbits Earth, its changing geometry with respect to the Sun produces the characteristic phases. This composite image is a mosaic made from 25 individual photos of the Moon and illustrates its phases over one synodic month. For complete details about this image, see Moon Phases Mosaic. The individual images included in this composite can be found in the Moon Phases Gallery. For more composites, see Moon Phases Mosaics. Photo copyright 2012 by Fred Espenak.

We tend to take the Moon for granted but it shares a unique history with Earth. Shortly after its formation 4.5 billion years ago, “proto-Earth” collided with a Mars-sized object called Theia. Much of “proto-Earth” and Theia merged to become our Earth, but the impact also ejected a large amount of material into space. Some of it coalesced to become the Moon (see: Giant Impact Hypothesis).

The Moon’s orbit stabilizes the axial tilt of Earth, preventing it from undergoing chaotic variations that would lead to catastrophic changes in climate. And the daily rise and fall of the Moon-induced tides has left an indelible imprint on Earth. Some scientists even argue whether life on Earth would be possible without the influence of the Moon (see: Without the Moon, Would There Be Life on Earth?).

With this big picture in mind, we gain a new appreciation for the Moon as we watch its phases, cycles, and motions during 2016.

As the Moon orbits Earth, its changing geometry with respect to the Sun produces the Moon’s characteristic phases (New Moon, First Quarter, Full Moon and Last Quarter). One orbit of the Moon relative to the Sun (the synodic month) has a mean duration of 29.53 days.

                   Moon Phases for 2016 (GMT)

   New Moon      First Quarter      Full Moon       Last Quarter
-------------    -------------    -------------    -------------   
                                                   Jan  2  05:30    
Jan 10  01:31    Jan 16  23:26    Jan 24  01:46    Feb  1  03:28    
Feb  8  14:39    Feb 15  07:46    Feb 22  18:20    Mar  1  23:11    
Mar  9  01:54T   Mar 15  17:03    Mar 23  12:01n   Mar 31  15:17    
Apr  7  11:24    Apr 14  03:59    Apr 22  05:24    Apr 30  03:29    
May  6  19:30    May 13  17:02    May 21  21:15    May 29  12:12    
Jun  5  03:00    Jun 12  08:10    Jun 20  11:02    Jun 27  18:19    
Jul  4  11:01    Jul 12  00:52    Jul 19  22:57    Jul 26  23:00    
Aug  2  20:45    Aug 10  18:21    Aug 18  09:27    Aug 25  03:41    
Sep  1  09:03A   Sep  9  11:49    Sep 16  19:05n   Sep 23  09:56    
Oct  1  00:12    Oct  9  04:33    Oct 16  04:23    Oct 22  19:14    
Oct 30  17:38    Nov  7  19:51    Nov 14  13:52    Nov 21  08:33    
Nov 29  12:18    Dec  7  09:03    Dec 14  00:06    Dec 21  01:56    
Dec 29  06:53                                                          

The table above lists the date and time of the Moon’s phases throughout 2016. The time of each phase is given in Greenwich Mean Time or GMT (a.k.a. Universal Time or UT). I’ve generated a table of the Moon’s phases covering 100 years on AstroPixels.com at Moon’s Phases – 21st Century (GMT). Similar 100-year tables for other time zones include Eastern Standard Time (EST), Central Standard Time (CST), Mountain Standard Time (MST), and Pacific Standard Time (PST). To convert GMT to other time zones, visit Time Zones.

What surprises many people is that the length of the synodic month can vary by over 6 hours from its mean value of 29.5306 days (29 days 12 hours 44 minutes). The table below gives the date of New Moon, the length of the synodic month, and the difference from the synodic month’s mean value for every synodic month in 2016. For instance, the fifth synodic month of 2016 (beginning May 06) is 5 hours 14 minutes shorter than the mean while the tenth month (beginning Oct 30) is 5 hours 56 minutes longer than the mean.

              Synodic Months for 2016 

   Date/Time of          Length of        Dif. from
  New Moon (GMT)       Synodic Month      Mean Month 
------------------     -------------     -----------
2016 Jan 10  01:31      29d 13h 08m       +00h 24m            
2016 Feb 08  14:39      29d 11h 16m       -01h 28m           
2016 Mar 09  01:54      29d 09h 29m       -03h 15m            
2016 Apr 07  11:24      29d 08h 06m       -04h 38m            
2016 May 06  19:29      29d 07h 30m       -05h 14m   shortest
2016 Jun 05  03:00      29d 08h 01m       -04h 43m            
2016 Jul 04  11:01      29d 09h 44m       -03h 01m            
2016 Aug 02  20:45      29d 12h 19m       -00h 25m            
2016 Sep 01  09:03      29d 15h 08m       +02h 24m            
2016 Oct 01  00:11      29d 17h 27m       +04h 43m            
2016 Oct 30  17:38      29d 18h 40m       +05h 56m   longest
2016 Nov 29  12:18      29d 18h 35m       +05h 51m            
2016 Dec 29  06:53      29d 17h 14m       +04h 30m            

The year 2008 had even greater extremes in the synodic month – from 5 hours 48 minutes shorter, to 6 hours 49 minutes longer than the mean value. So what causes these variations? The explanation involves the Moon’s elliptical orbit and its orientation with respect to the Sun during any given month. If New Moon occurs when the Moon is nearest to Earth (perigee), then the synodic month is shorter than normal. On the other hand, if New Moon occurs when the Moon is farthest from Earth (apogee), then the synodic month is longer than normal. Furthermore, the orientation of the Moon’s ellipse-shaped orbit slowly rotates in space with a period of about 18 years. A more detailed discussion on this topic can be found at Moon’s Orbit and the Synodic Month (EclipseWise.com). You can also find the duration of every synodic month this century at Length of the Synodic Month: 2001 to 2100 (AstroPixels.com).

Because the Moon orbits Earth in about 29.5 days with respect to the Sun, its daily motion against the background stars and constellations is quite rapid. It averages 12.2° per day. A table giving the Moon’s daily celestial coordinates throughout the year can be found at Moon Ephemeris for 2016 (AstroPixels.com). This table lists a lot of other details about the Moon including its daily distance, apparent size, libration, phase age (days since New Moon) and the phase illumination fraction.

When a Full Moon occurs within 90% of the Moon’s closest approach to Earth in a given orbit, it is called a perigee-syzygy or more commonly a Super Moon. The Full Moon then appears especially big and bright because it subtends its largest apparent diameter as seen from Earth. The table below lists the Super Moons occurring in 2016.

              Super Moons for 2016

   Full Moon     Distance  Diameter  Relative
    (GMT)          (km)    (arc-min) Distance

Sep 16  19:05 n   364754     32.76    0.934
Oct 16  04:23     358475     33.33    0.987
Nov 14  13:52     356523 m   33.52    1.000
Dec 14  00:06     359450     33.24    0.979

The Relative Distance listed in the Super Moon table expresses the Moon’s distance as a fraction between apogee (0.0) and perigee (1.0). For more information on Super Moons and a complete list of them for this century, see Full Moon at Perigee (Super Moon): 2001 to 2100 (AstroPixels.com).

Besides its obvious phases, the Moon also undergoes some additional extremes in its orbit including: Perigee and Apogee, Ascending/Descending Nodes, and Lunar Standstills. Each of these AstroPixels links covers lunar phenomena for the entire 21st Century.

Moon Phases Mosaic

A mosaic made from 9 individual photos of the Moon captures its phases over one synodic month. For complete details about this image, see Moon Phases Mosaic. The individual images included in this composite can be found in the Moon Phases Gallery. For more composites, see Moon Phases Mosaics. Photo copyright 2012 by Fred Espenak.

One of the first projects I tackled upon completing Bifrost Observatory in 2010 was to photograph the Moon’s phases every day for a complete month. Of course, the weather doesn’t always cooperate (even from sunny Arizona) so it actually took several months to complete the project. You can see the results at the Moon Phases Gallery. Clicking on any of the thumbnails pictures will give you an enlarged image with complete technical details. You can also visit Moon Phases Mosaics to see composites showing the Moon’s phases over a complete synodic month.

The NASA/Goddard Scientific Visualization Studio has used image data from the Lunar Reconnaissance Orbiter (LRO) mission to create clever animations of the Moon’s ever changing phases and librations in 2016. The example below illustrates the Moon’s phase and libration at hourly intervals throughout 2016, as viewed from the northern hemisphere. Each frame represents one hour.

And not to be accused of northern hemisphere chauvinism, here is a version as seen from the southern hemisphere.

Besides presenting the Moon’s phase and apparent size, these videos show the Moon’s orbit position, sub-Earth and subsolar points, distance from the Earth at true scale, and labels of craters near the terminator. As the Moon orbits Earth, it appears to wobble and tip on its axis. This motion is called libration and it allows us to see about 59% of the Moon’s surface (see Libration (EarthSky)). The major cause of libration is due to our changing line of sight because of the Moon’s elliptical orbit.

Ernie Wright of the NASA Scientific Visualization Studio has also used LRO data to create a web tool called Dial-A-Moon. Enter the month, day and hour and Dial-A-Moon will generate a visualization of the Moon showing the correct phase and libration for that instant during 2016 (see Moon Phase and Libration, 2016).

The last eclipse of the Moon visible from the USA occurred on the night of Sept. 27/28, 2015. It was a total eclipse as the Moon passed completely inside Earth's dark umbral shadow. ©2015 by Fred Espenak, MrEclipse.com.

The last eclipse of the Moon visible from the USA occurred on the night of Sept. 27/28, 2015. It was a total eclipse as the Moon passed completely inside Earth’s dark umbral shadow. ©2015 by Fred Espenak.

Finally, what discussion of the Moon would be complete without mentioning eclipses in 2016? There are two eclipses of the Moon and both of them are penumbral. The first occurs on March 23 and is visible from the western hemisphere. The second happens six months later on September 16 and is visible from the eastern hemisphere. Penumbral eclipses are very subtle events and often transpire without any notice (see: Visual Appearance of Penumbral Lunar Eclipses). But the 2016 eclipses are both deep penumbral eclipses so a pale shading should be visible around the time of mid-eclipse. By coincidence, the September 16 eclipse also happens to occur during a Super Moon.

Some sources identify a third penumbral eclipse on August 18. But this prediction depends on different assumptions about the size of Earth’s penumbral shadow. Even if you accept these assumptions, the eclipse barely occurs at all because only a scant 1.7% of the Moon’s diameter enters the penumbral shadow. For those who want to dig deeper into this subject, see: Enlargement of Earth’s Shadows. If such a small eclipse were to occur, it would be completely undetectable with even the largest telescopes on Earth.

There are also two solar eclipses in 2016. The first is a total eclipse on March 16 visible from Indonesia and parts of the Pacific Ocean. The second is an annular solar eclipse on September 01 visible from southern Africa and Madagascar. For complete details on all these events, see Eclipses During 2016 (EclipseWise.com).

Watching the Moon’s phases wax and wane as well as the occasional lunar eclipse can best be enjoyed with the naked eye and binoculars. And you don’t even need a dark sky since the Moon is easily visible from the heart of brightly lit cities.

The Moon phases and lunar phenomena discussed here were all generated with computer programs I’ve written (THINK Pascal and FORTRAN 90 running on a Macintosh G4 and MacBook Pro) using Astronomical Algorithms (Jean Meeus).

Fred Espenak


Moon in 2015

Moon Phases Mosaic

A mosaic made from 9 individual photos of the Moon captures its phases over one synodic month. For complete details about this image, see Moon Phases Mosaic. The individual images included in this composite can be found in the Moon Phases Gallery. For more composites, see Moon Phases Mosaics. Photo copyright 2012 by Fred Espenak.

As the Moon orbits Earth, its changing geometry with respect to the Sun produces the Moon’s characteristic phases (New Moon, First Quarter, Full Moon and Last Quarter). One orbit of the Moon relative to the Sun (the synodic month) has a mean duration of 29.53 days.

                    Moon Phases for 2015 (GMT)

   New Moon       First Quarter       Full Moon        Last Quarter
-------------     -------------     -------------     -------------   
                                    Jan  5  04:53     Jan 13  09:47    
Jan 20  13:14     Jan 27  04:48     Feb  3  23:09     Feb 12  03:50    
Feb 18  23:47     Feb 25  17:14     Mar  5  18:06     Mar 13  17:48    
Mar 20  09:36 T   Mar 27  07:43     Apr  4  12:06 t   Apr 12  03:44    
Apr 18  18:57     Apr 25  23:55     May  4  03:42     May 11  10:36    
May 18  04:13     May 25  17:19     Jun  2  16:19     Jun  9  15:42    
Jun 16  14:05     Jun 24  11:03     Jul  2  02:20     Jul  8  20:24    
Jul 16  01:24     Jul 24  04:04     Jul 31  10:43     Aug  7  02:03    
Aug 14  14:54     Aug 22  19:31     Aug 29  18:35     Sep  5  09:54    
Sep 13  06:41 P   Sep 21  08:59     Sep 28  02:50 t   Oct  4  21:06    
Oct 13  00:06     Oct 20  20:31     Oct 27  12:05     Nov  3  12:24    
Nov 11  17:47     Nov 19  06:27     Nov 25  22:44     Dec  3  07:40    
Dec 11  10:29     Dec 18  15:14     Dec 25  11:11                      

The table above lists the date and time of the Moon’s phases throughout 2015. The time of each phase is given in Greenwich Mean Time or GMT (a.k.a. Universal Time or UT). I’ve generated a table of the Moon’s phases covering 100 years at Moon’s Phases – 21st Century (GMT). Similar 100-year tables for other time zones include Eastern Standard Time (EST), Central Standard Time (CST), Mountain Standard Time (MST), and Pacific Standard Time (PST). To convert GMT to other time zones, visit Time Zones.

What surprises many people is that the length of the synodic month can vary by over 6 hours from its mean value of 29.5306 days (29 days 12 hours 44 minutes). The table below gives the date of New Moon, the length of the synodic month, and the difference from the synodic month’s mean value for every synodic month in 2015. For instance, the fourth synodic month of 2015 (beginning Apr 18) is 3 hours 28 minutes shorter than the mean while the tenth month (beginning Oct 13) is 4 hours 57 minutes longer than the mean.

              Synodic Months for 2015 

   Date/Time of          Length of        Dif. from
  New Moon (GMT)       Synodic Month      Mean Month 
------------------     -------------     -----------
2015 Jan 20  13:14      29d 10h 34m       -02h 10m
2015 Feb 18  23:47      29d 09h 49m       -02h 55m
2015 Mar 20  09:36      29d 09h 21m       -03h 23m
2015 Apr 18  18:57      29d 09h 16m       -03h 28m     shortest
2015 May 18  04:13      29d 09h 52m       -02h 52m
2015 Jun 16  14:05      29d 11h 19m       -01h 25m
2015 Jul 16  01:24      29d 13h 29m       +00h 45m
2015 Aug 14  14:53      29d 15h 48m       +03h 04m
2015 Sep 13  06:41      29d 17h 24m       +04h 40m
2015 Oct 13  00:06      29d 17h 41m       +04h 57m     longest
2015 Nov 11  17:47      29d 16h 42m       +03h 58m      
2015 Dec 11  10:29      29d 15h 01m       +02h 17m   

The year 2008 had even greater extremes in the synodic month – from 5 hours 48 minutes shorter, to 6 hours 49 minutes longer than the mean value. So what causes these variations? The explanation lies in the fact that the Moon’s orbit is elliptical. If New Moon occurs when the Moon is nearest to Earth (perigee), then the synodic month is shorter than normal. On the other hand, if New Moon occurs when the Moon is farthest from Earth (apogee), then the synodic month is longer than normal. Furthermore, the orientation of the Moon’s ellipse-shaped orbit slowly rotates in space with a period of about 18 years. A more detailed discussion on this topic can be found at Moon’s Orbit and the Synodic Month. You can also find the duration of every synodic month this century at Length of the Synodic Month: 2001 to 2100.

Because the Moon orbits Earth in ~29.5 days with respect to the Sun, its daily motion against the background stars and constellations is quite rapid. It averages about 12.2° per day. A table giving the Moon’s daily celestial coordinates throughout the year can be found at Moon Ephemeris for 2015. This table lists a lot of other details about the Moon including its daily distance, apparent size, libration, phase age (days since New Moon) and the phase illumination fraction.

When a Full Moon occurs within 90% of the Moon’s closest approach to Earth in a given orbit, it is called a Super Moon. The Full Moon then appears especially big and bright since it subtends its largest apparent diameter as seen from Earth. The table below lists the Super Moons occurring in 2015.

              Super Moons for 2015

   Full Moon     Distance  Diameter  Relative
    (GMT)          (km)    (arc-min) Distance

Jul 31  10:43     365112     32.73    0.930
Aug 29  18:35     358993     33.29    0.985
Sep 28  02:50 t   356878 m   33.48    1.000
Oct 27  12:05     359324     33.26    0.982
Nov 25  22:44     366149     32.64    0.921

The Relative Distance listed in the Super Moon table expresses the Moon’s distance as a fraction between apogee (0.0) and perigee (1.0). For more information on Super Moons and a complete list of them for this century, see Full Moon at Perigee (Super Moon): 2001 to 2100.

Besides its obvious phases, the Moon also undergoes some additional extremes in its orbit including: Perigee and Apogee, Ascending/Descending Nodes, and Lunar Standstills. Each of these links covers lunar phenomena for the entire 21st Century.

Moon Phases Mosaic

As the Moon orbits Earth, its changing geometry with respect to the Sun produces the characteristic phases. This composite image is a mosaic made from 25 individual photos of the Moon and illustrates its phases over one synodic month. For complete details about this image, see Moon Phases Mosaic. The individual images included in this composite can be found in the Moon Phases Gallery. For more composites, see Moon Phases Mosaics. Photo copyright 2012 by Fred Espenak.

One of the first projects I tackled upon completing Bifrost Observatory in 2010 was to photograph the Moon’s phases every day for a complete month. Of course, the weather doesn’t always cooperate (even from sunny Arizona) so it actually took several months to complete the project. You can see the results at the Moon Phases Gallery. Clicking on any of the thumbnails pictures will give you an enlarged image with complete technical details. You can also visit Moon Phases Mosaics to see composites showing the Moon’s phases over a complete synodic month.

The NASA/Goddard Scientific Visualization Studio has used images from the Lunar Reconnaissance Orbiter (LRO) mission to create clever animations of the Moon’s ever changing phases and librations in 2015. The example below illustrates the Moon’s phase and libration at hourly intervals throughout 2015, as viewed from the northern hemisphere. Each frame represents one hour.

Besides presenting the Moon’s phase and apparent size, the video shows the Moon’s orbit position, sub-Earth and subsolar points, distance from the Earth at true scale, and labels of craters near the terminator. As the Moon orbits Earth, it appears to wobble and tip on its axis. This motion is called libration and it allows us to see about 59% of the Moon’s surface. The major cause of libration is due to our changing line of sight because of the Moon’s elliptical orbit. For more Moon animations from NASA/Goddard, see Moon Phase and Libration, 2015.

Finally, what discussion of the Moon would be complete without mentioning eclipses in 2015? There are two eclipses of the Moon and both of them are total. The first occurs on April 04 and the second, six months later on September 28. Both of them are visible from parts of North America. By coincidence, the September 28 eclipse also happens to be the closest Super Moon of 2015.

There are also two solar eclipses in 2015. The first is a total eclipse in the North Atlantic on March 20 (visible from the Faroe Islands and Spitzbergen). The second is a partial solar eclipse visible from most of southern Africa and Antarctica on September 13. For complete details on all these events, see Eclipses During 2015 (EclipseWise.com).

Watching the Moon’s phases wax and wane as well as the occasional lunar eclipse can best be enjoyed with the naked eye and binoculars. And you don’t even need a dark sky since the Moon is easily visible from the heart of brightly lit cities.

The Moon phases and lunar phenomena discussed here were all generated with computer programs I’ve written (THINK Pascal and FORTRAN 90 running on a Macintosh G4) using Astronomical Algorithms (Jean Meeus).

Fred Espenak


Moon in 2014

Moon Phases Mosaic

As the Moon orbits Earth, its changing geometry with respect to the Sun produces the characteristic phases. This composite image is a mosaic made from 25 individual photos of the Moon and illustrates its phases over one synodic month. For complete details about this image, see Moon Phases Mosaic. The individual images included in this composite can be found in the Moon Phases Gallery. For more composites, see Moon Phases Mosaics. Photo copyright 2012 by Fred Espenak.

As the Moon orbits Earth, its changing geometry with respect to the Sun produces the Moon’s characteristic phases (New Moon, First Quarter, Full Moon and Last Quarter). One orbit of the Moon relative to the Sun (the synodic month) has a mean duration of 29.53 days.

The table below lists the date and time of the Moon’s phases throughout 2014. The time of each phase is given in Greenwich Mean Time or GMT (a.k.a. Universal Time or UT). To convert GMT to Eastern Standard Time (EST) just subtract 5 hours. To convert GMT to other time zones, visit Time Zones.

                    Moon Phases for 2014 (GMT)

   New Moon      First Quarter      Full Moon       Last Quarter
-------------    -------------    -------------    -------------   
Jan  1  06:14    Jan  7  22:39    Jan 15  23:52    Jan 24  00:19    
Jan 30  16:39    Feb  6  14:22    Feb 14  18:53    Feb 22  12:15    
Mar  1  03:00    Mar  8  08:27    Mar 16  12:09    Mar 23  20:46    
Mar 30  13:45    Apr  7  03:31    Apr 15  02:42    Apr 22  02:52    
Apr 29  01:14    May  6  22:15    May 14  14:16    May 21  07:59    
May 28  13:40    Jun  5  15:39    Jun 12  23:11    Jun 19  13:39    
Jun 27  03:09    Jul  5  06:59    Jul 12  06:25    Jul 18  21:08    
Jul 26  17:42    Aug  3  19:50    Aug 10  13:09    Aug 17  07:26    
Aug 25  09:13    Sep  2  06:11    Sep  8  20:38    Sep 15  21:05    
Sep 24  01:14    Oct  1  14:33    Oct  8  05:51    Oct 15  14:12    
Oct 23  16:57    Oct 30  21:48    Nov  6  17:23    Nov 14  10:16    
Nov 22  07:32    Nov 29  05:06    Dec  6  07:27    Dec 14  07:51    
Dec 21  20:36    Dec 28  13:31                                        

I’ve generated a table of the Moon’s phases covering 100 years at Moon’s Phases – 21st Century (GMT). Similar 100-year tables for other time zones include Eastern Standard Time (EST), Central Standard Time (CST), Mountain Standard Time (MST), and Pacific Standard Time (PST).

What surprises many people is that the length of the synodic month can vary by over 6 hours from its mean value of 29.5306 days (29 days 12 hours 44 minutes). The table below gives the date of New Moon, the length of the synodic month, and the difference from the synodic month’s mean value for every synodic month in 2014. For instance, the first synodic month of 2014 is 2 hours 20 minutes shorter than the mean while the nineth month (beginning Aug 25) is 3 hours 17 minutes longer than the mean.

              Synodic Months for 2014 

   Date/Time of        Length of     Dif. from
  New Moon (GMT)     Synodic Month   Mean Month 
------------------   -------------  -----------
2014 Jan 01  11:14    29d 10h 24m    -02h 20m
2014 Jan 30  21:39    29d 10h 21m    -02h 23m 
2014 Mar 01  08:00    29d 10h 45m    -01h 59m
2014 Mar 30  18:45    29d 11h 30m    -01h 14m
2014 Apr 29  06:14    29d 12h 26m    -00h 18m
2014 May 28  18:40    29d 13h 28m    +00h 44m
2014 Jun 27  08:08    29d 14h 33m    +01h 49m
2014 Jul 26  22:42    29d 15h 31m    +02h 47m
2014 Aug 25  14:13    29d 16h 01m    +03h 17m 
2014 Sep 24  06:14    29d 15h 43m    +02h 59m
2014 Oct 23  21:57    29d 14h 36m    +01h 52m
2014 Nov 22  12:32    29d 13h 04m    +00h 20m
2014 Dec 22  01:36    29d 11h 38m    -01h 06m

The year 2008 had even greater extremes in the synodic month – from 5 hours 48 minutes shorter, to 6 hours 49 minutes longer than the mean value. So what causes these variations? The explanation lies in the fact that the Moon’s orbit is elliptical. If New Moon occurs when the Moon is nearest to Earth (perigee), then the synodic month is shorter than normal. On the other hand, if New Moon occurs when the Moon is farthest from Earth (apogee), then the synodic month is longer than normal. Furthermore, the orientation of the Moon’s ellipse-shaped orbit slowly rotates in space with a period of about 18 years. A more detailed discussion on this topic can be found at Moon’s Orbit and the Synodic Month. You can also find the duration of every synodic month this century at Length of the Synodic Month: 2001 to 2100.

Because the Moon orbits Earth in ~29.5 days with respect to the Sun, its daily motion against the background stars and constellations is quite rapid. It averages about 12.2° per day. A table giving the Moon’s daily celestial coordinates throughout the year can be found at 2014 Moon Ephemeris. This table lists a lot of other details about the Moon including its daily distance, apparent size, libration, phase age (days since New Moon) and the phase illumination fraction. See the above table for descriptions of all these terms.

A Super Moon is a Full Moon that occurs within 90% of the Moon’s closest approach to Earth in a given orbit. The Full Moon then appears especially big and bright since it subtends its largest apparent diameter as seen from Earth. The table below lists the Super Moons occurring in 2014.

              Super Moons for 2014 

   Full Moon     Distance  Diameter  Relative
    (GMT)          (km)    (arc-min) Distance

Jun 13  04:11     365038     32.73    0.931
Jul 12  11:25     358975     33.29    0.985
Aug 10  18:09     356898     33.48    1.000
Sep 09  01:38     359182     33.27    0.983
Oct 08  10:51     365659     32.68    0.925

The Relative Distance listed in this table expresses the Moon’s distance as a fraction between apogee (0.0) and perigee (1.0). For much more on Super Moons and a complete list of them for this century, see Full Moon at Perigee (Super Moon): 2001 to 2100.

Besides its obvious phases, the Moon also undergoes some additional extremes in its orbit including: Perigee and Apogee, Ascending/Descending Nodes, and Lunar Standstills. Each of the above links covers lunar phenomena for the entire 21st Century.

Moon Phases Mosaic

A mosaic made from 9 individual photos of the Moon captures its phases over one synodic month. For complete details about this image, see Moon Phases Mosaic. The individual images included in this composite can be found in the Moon Phases Gallery. For more composites, see Moon Phases Mosaics. Photo copyright 2012 by Fred Espenak.

One of the first projects I tacked upon completing Bifrost Observatory in 2010 was to photograph the Moon’s phases every day for a complete month. Of course, the weather doesn’t always cooperate (even from sunny Arizona) so it actually took several months to complete the project. You can see the results at the Moon Phases Gallery. Clicking on any of the thumbnails pictures will give you an enlarged image with complete technical details. You can also visit Moon Phases Mosaics to see composites showing the Moon’s phases over a complete synodic month.

Last year (2013), NASA’s Lunar Reconnaissance Orbiter (LRO) team created clever animation using data from both the LRO and Clementine missions. It illustrates the Moon’s phases throughout 2013 at 1-hour intervals.

Besides presenting the Moon’s phase and apparent size, the video shows the Moon’s orbital position with respect to the Sun and Earth, and it’s distance from Earth. As the Moon orbits Earth, it appears to wobble and tip on its axis. This motion is called libration and it allows us to see about 59% of the Moon’s surface. The major cause of libration is due to our changing line of sight because of the Moon’s elliptical orbit.

Finally, what discussion of the Moon would be complete without mentioning eclipses in 2014? There are two eclipses of the Moon and both of them are total. The first occurs on April 15 and the second, six months later on October 8. Both of them are well placed for viewing from North America. There are also two solar eclipses. The first is an annular eclipse in Antarctica on April 29 (a partial eclipse is visible from Australia). The second is a partial solar eclipse visible from most of North America on October 23. I’ve written an article with more information at Eclipses During 2014.

Watching the Moon’s phases wax and wane as well as the occasional lunar eclipse can best be enjoyed with the naked eye and binoculars. And you don’t even need a dark sky since the Moon is easily visible from the heart of brightly lit cities.

The Moon phases and lunar phenomena discussed here were all generated with computer programs I’ve written (THINK Pascal running on a Macintosh G4) using Astronomical Algorithms (Jean Meeus).

Fred Espenak

Moon Phases for 2013

Moon Phases Mosaic

This composite image is a mosaic made from 25 individual photos of the Moon and illustrates its phases over one synodic month. For complete details about this image, see Moon Phases Mosaic. The individual images included in this composite can be found in the Moon Phases Gallery. For more composites, see Moon Phases Mosaics. Photo copyright 2012 by Fred Espenak.

As the Moon orbits Earth, its changing geometry with respect to the Sun produces the Moon’s characteristic phases (New Moon, First Quarter, Full Moon and Last Quarter). One orbit of the Moon relative to the Sun (the synodic month) has a mean duration of 29.53 days.

The table below lists the time and date of the Moon’s phases throughout 2013. The time of each phase is given in Greenwich Mean Time or GMT (a.k.a. Universal Time or UT). To convert GMT to Eastern Standard Time (EST) just subtract 5 hours. To convert GMT to other time zones, visit Time Zones.

                    Moon Phases for 2013 (GMT)

   New Moon      First Quarter      Full Moon       Last Quarter
-------------    -------------    -------------    -------------   
                                                   Jan  5  03:58    
Jan 11  19:44    Jan 18  23:45    Jan 27  04:38    Feb  3  13:56    
Feb 10  07:20    Feb 17  20:31    Feb 25  20:26    Mar  4  21:53    
Mar 11  19:51    Mar 19  17:27    Mar 27  09:27    Apr  3  04:37    
Apr 10  09:35    Apr 18  12:31    Apr 25  19:57    May  2  11:14    
May 10  00:29    May 18  04:35    May 25  04:25    May 31  18:58    
Jun  8  15:56    Jun 16  17:24    Jun 23  11:32    Jun 30  04:54    
Jul  8  07:14    Jul 16  03:18    Jul 22  18:15    Jul 29  17:43    
Aug  6  21:51    Aug 14  10:56    Aug 21  01:45    Aug 28  09:35    
Sep  5  11:36    Sep 12  17:08    Sep 19  11:13    Sep 27  03:56    
Oct  5  00:35    Oct 11  23:02    Oct 18  23:38    Oct 26  23:41    
Nov  3  12:50    Nov 10  05:57    Nov 17  15:16    Nov 25  19:28    
Dec  3  00:22    Dec  9  15:12    Dec 17  09:28    Dec 25  13:48    

I’ve generated a Moon phases table covering 100 years at Moon’s Phases – 21st Century (GMT). Similar 100-year tables for other time zones include Eastern Standard Time (EST), Central Standard Time (CST), Mountain Standard Time (MST), and Pacific Standard Time (PST).

What surprises many people is that the length of the synodic month can vary by over 6 hours from its mean value of 29.5306 days (29 days 12 hours 44 minutes). The table below gives the date of New Moon, the length of the synodic month, and the difference from the synodic month’s mean value, for every synodic month in 2013. For instance, the first synodic month of 2013 is 1 hour 7 minutes shorter than the mean while the fifth month (beginning May 10) is 2 hours 43 minutes longer than the mean.

              Synodic Months for 2013 

   Date/Time of        Length of     Dif. from
  New Moon (GMT)     Synodic Month   Mean Month 
------------------   -------------  -----------
2013 Jan 11  19:44    29d 11h 37m    -01h 07m
2013 Feb 10  07:20    29d 12h 32m    -00h 12m
2013 Mar 11  19:51    29d 13h 45m    +01h 00m
2013 Apr 10  09:35    29d 14h 53m    +02h 09m
2013 May 10  00:29    29d 15h 27m    +02h 43m
2013 Jun 08  15:56    29d 15h 17m    +02h 33m
2013 Jul 08  07:14    29d 14h 35m    +01h 51m
2013 Aug 06  21:51    29d 13h 45m    +01h 01m
2013 Sep 05  11:36    29d 12h 58m    +00h 14m
2013 Oct 05  00:35    29d 12h 15m    -00h 29m
2013 Nov 03  12:50    29d 11h 33m    -01h 11m
2013 Dec 03  00:22    29d 10h 53m    -01h 51m

The year 2008 had even greater extremes in the synodic month – from 5 hours 48 minutes shorter, to 6 hours 49 minutes longer than the mean value. So what causes these variations? The explanation lies in the fact that the Moon’s orbit is elliptical. If New Moon occurs when the Moon is nearest to Earth (perigee), then the synodic month is shorter than normal. On the other hand, if New Moon occurs when the Moon is farthest from Earth (apogee), then the synodic month is longer than normal. Furthermore, the orientation of the Moon’s ellipse-shaped orbit slowly rotates in space with a period of about 18 years. A more detailed discussion on this topic must await a future blog post.

Besides its obvious phases, the Moon also undergoes some additional extremes in its orbit including: Perigee and Apogee, Ascending/Descending Nodes, and Lunar Standstills. Each of the above links covers lunar phenomena for the entire 21st Century.

The Moon phases and lunar phenomena tables were all generated with a computer program I wrote (THINK Pascal running on a Macintosh G4) using Astronomical Algorithms (Jean Meeus).

Moon Phases Mosaic

A mosaic made from 9 individual photos of the Moon captures its phases over one synodic month. For complete details about this image, see Moon Phases Mosaic. The individual images included in this composite can be found in the Moon Phases Gallery. For more composites, see Moon Phases Mosaics. Photo copyright 2012 by Fred Espenak.

One of the first projects I tacked upon completing Bifrost Observatory in 2010 was to photograph the Moon’s phases every day for a complete month. Of course, the weather doesn’t always cooperate (even from sunny Arizona) so it actually took several months to complete the project. You can see the results at the Moon Phases Gallery. Clicking on any of the thumbnails pictures will give you an enlarged image with complete technical details. You can also visit Moon Phases Mosaics to see composites showing the Moon’s phases over a complete synodic month.

The clever animation below illustrates the Moon’s phases throughout 2013 (at 1-hour intervals). NASA’s Lunar Reconnaissance Orbiter (LRO) team created the video using data from both LRO and Clementine (a 1990s lunar orbiter mission).

Besides presenting the Moon’s phase and apparent size, the video shows the Moon’s orbital position with respect to the Sun and Earth, and it’s distance from Earth. As the Moon orbits Earth, it appears to wobble and tip on its axis. This motion is called libration and it allows us to see about 59% of the Moon’s surface. The major cause of libration is due to our changing line of sight because of the Moon’s elliptical orbit.

Watching the Moon’s phases wax and wane can best be enjoyed with the naked eye and binoculars. And you don’t even need a dark sky since the Moon is easily visible from the heart of brightly lit cities.

Fred Espenak

Moon Halo

Have you ever seen an enormous hazy ring surrounding the Moon? This is an atmospheric phenomenon that goes by a number of names including Moon Ring, Moon Halo, and Winter Halo.

The halo appears as a whitish ring over 80 times the diameter of the Moon, and centered on the lunar orb. It only occurs when a thin veil of high cirrus clouds covers the sky, which often precedes a change in the weather as a cold front approaches. The cirrus clouds are composed of hexagonal ice crystals suspended in the upper atmosphere. Each ice crystal acts like tiny 6-sided prism with 60° sides.

Moon Halo

A halo around the Moon can form when the ice crystals in high altitude clouds refract the Moon’s light into a ring. For complete details about this image, see Moon Halo. Photo copyright 2012 by Fred Espenak

As bright moonlight shines through the ice crystals, some of the light rays are refracted or bent through an angle of approximately 22°. The actual angle of refraction depends on the color of the light. For instance, red light is refracted about 21.54° while blue light is refracted 22.37°. Since the Moon’s light is simply reflected sunlight, it consists of all the colors of the rainbow. This gives the inner edge of the halo a reddish tinge while the outer edge is bluish.

The resulting Moon halo has an apparent radius of 22° (or a diameter of 44°). It is several degrees thick because the Moon itself is 1/2 degree in diameter, and the ice crystals are randomly oriented in the cirrus clouds. These factors tend to spread the ring out a few degrees.

Moon halos are best seen when the Moon is within several days of Full Moon. Because the Moon is then at its brightest, it is easier to see a faint Winter Halo if the weather conditions are right. This 22° halo phenomenon is also visible around the Sun but is frequently overlooked because of the Sun’s intense glare. By covering the Sun with your outstretched hand it’s easier to spot a Sun Halo.

Fred Espenak