The Waxing Moon of Spring


 

Four-Day-Old Moon with EarthshineSpring is the season for Earthshine on the waxing Moon.

April 8 was the perfect night for capturing the waxing crescent Moon illuminated both by the Sun and by the Earth.

The phase was a 4-day-old Moon, old enough to be high in the sky, but young enough – i.e. a thin enough crescent – that its bright side didn’t wash out the dark side!

In the lead photo at top, and even in the single-exposure image below taken earlier in a brighter sky, you can see the night side of the Moon faintly glowing a deep blue, and brighter than the background twilight sky.

Four-Day-Old Moon in Blue Twilight
The 4-day-old waxing crescent Moon on April 8, 2019 in a single exposure when the Moon was still in the bright blue twilight. Even so, the faint Earthshine is just becoming visible. This is with the 105mm Traveler refractor and 2X AP Barlow lens for an effective focal length of 1200mm at f/12, and with the cropped-frame Canon 60Da at ISO 400, in a single 1/8-second exposure.

This, too, is from sunlight, but light that has bounced off the Earth first to then light up the night side of the Moon.

If you were standing on the lunar surface on the night side, the Sun would be below the horizon but your sky would contain a brilliant blue and almost Full Earth lighting your night, much as the Moon lights our Earthly nights. However, Earth is some 80 times brighter in the Moon’s sky than even the Full Moon is in our sky.

Four-Day-Old Moon with Earthshine
The 4-day-old waxing crescent Moon on April 8, 2019 in a blend of short and long exposures to bring out the faint Earthshine on the dark side of the Moon and deep blue twilight sky while retaining details in the bright sunlit crescent. This is with the 105mm Traveler refractor and 2X AP Barlow lens for an effective focal length of 1200mm at f/12, and with the cropped-frame Canon 60Da at ISO 400, in a blend of 7 exposures from 1/30 second to 2 seconds, blended with luminosity masks from ADP Pro3 extension panel in Photoshop.

 

Unlike the single image, the lead image, repeated just above, is a multi-exposure blend (using luminosity masks), to bring out the faint Earthshine and deep blue sky, while retaining details in the bright crescent.

Once the sky gets dark enough to see Earthshine well, no single exposure can record the full range in brightness on both the day and night sides of the Moon.

 

Waxing Moon, Mars and the Taurus Clusters
The 4-day-old waxing crescent Moon on April 8, 2019 with it below Mars (at top) and the star clusters, the Hyades (at left, with reddish Aldebaran) and Pleiades (at right) in Taurus, and set into the deep blue evening twilight. This is with the 135mm Canon telephoto at f/2.8 with the Canon 6D at ISO 400, in a blend of 7 exposures from 1/4 second to 8 seconds, blended with luminosity masks from ADP Pro3 extension panel in Photoshop, to prevent the Moon from being too overexposed while retaining the stars and blue sky. The camera was tracking the sky.

April 8 was a great night for lunar fans as the crescent Moon also appeared between the two bright star clusters in Taurus, the Hyades and Pleiades, and below reddish Mars.

It was a fine gathering of celestial sights, captured above with a telephoto lens.

April 8 Sky

This show the chart I used to plan the framing, created with StarryNight™ software and showing the field of the 135mm lens I used.

The chart also shows why spring is best for the waxing Moon. It is at this time of year that the ecliptic – the green line – swings highest into the evening sky, taking the Moon with it, placing it high in the west above obscuring haze.

That makes it easier to see and shoot the subtle Earthshine. And to see sharp details on the Moon.

After the sky got darker I shot the crescent Moon in a short exposure to capture just the bright crescent, included above in two versions – plain and with labels attached marking the major features visible on a 4-day Moon.

If you missed “Earthshine night” this month, mark May 7 and 8 on your calendar for next month’s opportunities.

Clear skies!

— Alan, April 9, 2019 / © 2019 Alan Dyer / AmazingSky.com 

 

Follow Comet Wirtanen


Comet Wirtanen / 46P on December 6, 2018

A well-known comet is making its closest approach to Earth in many years and promises a good show. 

Comet Wirtanen is now climbing up the late autumn and winter sky for northern hemisphere viewers, and is already a fine binocular comet. By mid-December it might be bright enough to be visible to the naked eye, but only from a dark rural site.

Discovered in 1948 by Carl Wirtanen at the Lick Observatory, his namesake comet orbits the Sun every 5.4 years. So unlike other recent bright comets that have visited us for the first time, Comet Wirtanen (aka 46P) is well known. It is one of many “Jupiter-family” comets whose orbits have been shaped by the gravity of Jupiter and orbit the Sun about every 6 years.

So since it was discovered, Comet 46P (the 46th comet in the catalog of periodic comets) has been well observed. It isn’t better known because at most returns it never gets bright, and that’s because it never gets closer to the Sun than a little more than the distance from the Earth to the Sun. (Its perihelion distance is 1.06 AU, with 1 AU, or Astronomical Unit, being the average distance from Earth to the Sun.)

However, despite this, we’re expecting – indeed already enjoying – a good show at this return.

Due to the quirk of orbital clockwork, on this return the comet reaches its closest point to the Sun just before it is also closest to Earth.

That puts the comet “just” 11,680,000 kilometres from us at its closest approach to Earth on December 16, four days after perihelion, the point when the comet is closest to the Sun.

Comet Wirtanen from Space
The relative position of the Sun, Earth and Comet Wirtanen on December 16, 2018.

Comet Wirtanen will be relatively bright simply by virtue of its proximity.

But it is also an active comet, emitting a lot of gas and dust into a large “coma,” and that’s what we see, not the 1-kilometre-wide icy nucleus itself which is too small and shrouded by the coma. (As a footnote, Comet Wirtanen was to have been the comet that the European Rosetta probe was to visit, but launch delays forced ESA to switch cometary targets.)

Comet Wirtanen is glowing at magnitude 5 to 6, technically making it visible to the naked eye. However, because it is large and diffuse, in practice you need binoculars to see it – now.

But as it approaches Earth and the Sun, Wirtanen will brighten, perhaps to magnitude 3 (the brightest stars are magnitude 0 to 1), making it easier to see with the unaided eye from a dark site.

The one catch is that as it heads toward its brightest in mid-December the waxing Moon also begins to enter the sky and wash out the comet with moonlight.


The first two weeks of December will be prime time for Wirtanen


Comet Wirtanen Path
The path of Comet Wirtanen across the sky in December 2018. The yellow dots mark the position of the comet at nightly intervals for late evening (10 p.m.) for North America. While comet will be in the sky most of the night, it will be highest in late evening about 10 p.m. local time when the sky will look as depicted, with the comet high in the south to southeast. Click or tap to download a full-sized version.

The first two weeks of December will be prime time for Wirtanen, with a particularly good opportunity coming on the evenings of December 15 and 16 when it shines below the Pleiades star cluster. The gibbous Moon will set about 1 to 2 a.m. with the comet still high enough for a dark sky view and photos.

Those will be great nights to shoot the comet and the cluster with a telephoto lens, provided the camera is on a tracker for untrailed exposures of 1 to 4 minutes. A 135mm to 300mm lens will frame the pair well.

Winter Green Comet with Orion
Comet Wirtanen as a green glow at upper right here in Eridanus. and well to the west of Orion, rising here at left, on the evening of December 6, 2018. I shot this with a wide-angle 35mm lens in a blend of tracked and untracked 1-minute exposures.

After that, through late December, the bright Moon will interfere with  the view. For example, a close approach of the comet near the star Capella on December 23 happens with the nearly Full Moon not far away.

Comet Wirtanen / 46P on December 6, 2018
Comet Wirtanen in a close-up through a telescope on December 6, 2018 in a stack of short and long exposures.

I took the above close-up photo of Comet Wirtanen on December 6. It is a long-exposure telescopic view, but the comet is easy to see with binoculars. It appears visually and photographically as a diffuse fuzzball, with the camera recording a vivid cyan colour from glowing cyanogen and diatomic carbon molecules. You won’t see that colour with your eyes, even in a telescope.

Comet Wirtanen Path Dec 8 to 16
The path of Comet Wirtanen Dec 8 to 16 superimposed on an actual sky image with the comet taken December 8. The circle indicates the field of view of typical binoculars. On Dec 15 and 16 the comet will be in the same binocular field as the Pleiades star cluster. The positions are for about 10 pm Mountain Standard Time for each of those dates.

Even at the comet’s best in mid-December any tail might be hard to see and even photograph (it appears faintly above) as it will be both faint and pointed directly away from us because, as comet tails do, it will also be pointed away from the Sun.

Look for a large glow which will be grey to the eye but green to the camera.

While you can just take pictures for yourself, astronomers are asking amateur astrophotographers to participate in a worldwide observing campaign to monitor Comet Wirtanen. More details are available here at wirtanen.astro.umd.edu and at http://aop.astro.umd.edu/

Clear skies and happy comet hunting!

— Alan, November 30, 2018 (Revised December 6) / © 2018 Alan Dyer / AmazingSky.com 

The Rise and Set of the Easter Full Moon


Rising Easter Full Moon (Composite)

A clear day on Easter Eve allowed me to photograph the setting Full Moon in the morning and the rising Full Moon in the evening.

This was another of the year’s special Full Moons, and this time for a valid historical reason.

This was the “paschal” Full Moon, the one used to determine the date of Easter. It was the first Full Moon after the vernal equinox. The first Sunday after that Full Moon is Easter. This year, the Moon was full about an hour before sunrise on the morning of Saturday, March 31. Easter was the next day, Sunday, April 1.

Below is the view of the Full Moon not long after it was officially Full, as it was setting into the west as the first rays of sunlight lit the foreground at dawn on March 31.

The Easter Full Moonset #1 (March 31, 2018)
The setting Full Moon on the morning of Saturday, March 31, 2018, the day before Easter. At this time, at about 7:20 a.m. MDT, the Moon was a little less than an hour after the moment of exact Full Moon, so the Sun had already risen before the Moon set. This was with the Canon 6D MkII and 200mm lens with 1.4x convertor, shot from home.

To be precise, the actual paschal Full Moon is a fictional or calculated Moon that occurs 14 days into the lunar cycle, and isn’t an observed Moon. But this year, we really did have a Full Moon just before Easter Sunday, and on the first day of Passover, from which we get the term “paschal.”

Later on March 31, after sunset, the Moon was now half a day past Full, causing it to rise a good half hour after sunset. However, the lighting and sky colour was still good enough to place a reddened Moon rising into a deep blue sky for a wonderful colour contrast.

This was also touted as a “blue Moon,” as it was the second Full Moon in March, and it was also the second blue Moon of 2018. (January had one, too.) But as you can see the Moon was hardly “blue!” It was a fine pink Moon.

Rising Easter Full Moon (Trail)
This is a stack of 424 exposueres, taken at 3-second intervals for a time-lapse, but here stacked with Lighten blend mode to create a moon trail streak. I used the Advanced Stacker Plus actions in Photoshop. The final Moon disk comes from the last image in the sequence, while the ground comes from the first image in the sequence. I shot this sequence from home, using a 200mm Canon lens and 1.4x convertor, on the Canon 6D MkII. Exposures ranged from 0.8 second to 1/15 second, all at ISO 100 and f/4.

The above image is a little fun with Photoshop, and stacks hundreds of images of the rising Moon to create a “Moon trail,” showing the change in colour of the Moon as it rose.

This short HD movie includes two versions of the full time-lapse sequence:

• One showing the Moon rising normally, though the sky and ground come from the first image in the sequence.

• The second is another bit of Photoshop fun, with the Moon leaving disks behind it as it rose.

For the technically minded, I created both movies using Photoshop’s video editing capabilities to layer in various still images on top of the base video file. The stills are layered with a Lighten blend mode to superimpose them onto the background sky and video.

Rising Moon Movie Composite Screenshot
A screen shot of the Photoshop layers used to create the Moon disk composite time-lapse.

While Easter is a spring holiday, it hardly seems spring here in Alberta. The coldest Easter weekend in decades and lots of snow on the ground made this a winter scene.

With luck, spring will arrive here well before the next Full Moon.

— Alan, April 3, 2018 / © 2918 Alan Dyer / amazingsky.com 

 

Mercury, Moon, and Mirages


Rising and Distorted Supermoon on New Year's Day

Happy New Year to all!  

New Year’s Day proved to be a busy one for sky sights from home in southern Alberta.

Clear skies and warming temperatures allowed me to capture a trio of sights on January 1: Mercury in the morning, a unique mirage called the Fata Morgana in the afternoon, and the rising Full Moon in the evening.

On January 1 elusive Mercury was at its greatest elongation away from the Sun in the morning sky. This placed it as high as it can get above the horizon, though that’s not high at all at the best of times.

Mercury in the Morning on New Year's Day
Mercury at dawn in the southeast sky.

I captured Mercury before dawn as a bright star in the colourful twilight, using a telephoto lens to frame the scene more closely.

At this time the temperature outside was still about -24° C, as a cold snap that had plunged the prairies into frigid air for the last week still held its grip.

But by the afternoon, warmer air was drifting in from the west, in a Chinook flow from the Rockies.

As evidence of the change, the air exhibited a form of mirage called the Fata Morgana, named after the sorceress Morgan le Fay of Arthurian legend. The illusion of castles in the air was thought to be a spell cast by her to lure sailors to their doom.

Fata Morgana Mirage on the Prairies
A Fata Morgana mirage on the Prairies

The mirage produced the illusion of bodies of water in the distance, plus distorted, elongated forms of wind turbines and farm buildings on the horizon. The cause is the refraction of light by layers of warm air aloft, above cold air near the ground.

By evening the mirage effect was still in place, producing a wonderful moonrise with the Full Moon writhing and rippling as it rose through the temperature inversion.

As the lead image at top shows, at moments the top of the disk had a green rim (almost a distinct green flash), while the bottom was tinted red.

Here’s a short time-lapse video of the scene, shot through a small telescope. The lead image above and below is a composite of four of the frames from this movie.

Rising and Distorted Supermoon on New Year's Day
A composite of 4 exposures of the rising Full Moon on New Year’s Day, 2018, rising from left to right over a snowy prairie horizon in southern Alberta. This is a composite of 4 out of 500 images shot for a time-lapse sequence, layered in Photoshop. All were with a 66mm f/7 William Optics apo refractor and Canon 60Da camera firing 1/25th second exposures every 1 second.

This was also the largest and closest Full Moon of the year, what has become popularly called a “supermoon,” but more correctly called a perigean Full Moon.

A lunar cycle from now, at the next Full Moon, the Moon undergoes a total eclipse in the dawn hours of January 31 for western North America. This will be another misnamed Moon, a “blue Moon,” the label for the second Full Moon in a calendar month.

And some will also be calling it a “supermoon,” as it also occurs close to perigee – the closest point of the Moon to Earth in its monthly orbit – but not as close a perigee as it was at on January 1.

So it will be less than super, but it will nevertheless be spectacular as the Full “blue” Moon turns red as it travels through Earth’s shadow.

— Alan, January 2, 2018 / © 2018 Alan Dyer / amazingsky.com

 

Dawn Sky Delights


Aldebaran About to be Occulted by the Moon

It was one of those mornings when the sky was full of wonder.

After days and nights of smoke from unfortunate fires burning not far away, including in my favourite national park of Waterton Lakes, the sky cleared enough this morning, September 12, to reveal some fine sights.

At 6 a.m. the waning gibbous Moon passed in front of the star Aldebaran in Taurus. It is performing many such occultations of Aldebaran this year, but most aren’t well seen from any one location. This one was ideal, right from my backyard.

The lead image is a “high dynamic range” stack of several exposures showing the waning Moon and star set in some high haze adding the sky colours.

The star winked out behind the Moon’s bright limb as the Moon advanced from right to left (west to east) against the background sky.

Occultation of Aldebaran
Aldebaran nearing the limb of the Moon.
This shows a composite sequence, with images of the star taken every four minutes blended with a single image of the Moon. While it looks like the star is moving, it is really the Moon that is edging closer to Aldebaran.

The star reappeared from behind the dark limb of the Moon, but five minutes after sunrise, with the Moon in a bright blue sky. Still, the star stood out nicely in binoculars and in the telescope for this view.

Aldebaran Near the Moon in Day Sky
Aldebaran off the dark limb of the Moon.
Aldebaran is the point of light at right, just off the invisible edge of the Moon.

I shot stills and video, and compiled them into this short video.

Enlarge it to full screen to view it properly.

Meanwhile, over to the east the twilight sky was awash in planets.

Rocky Planets at Dawn with Labels (Sept. 12, 2017)
The line of dawn planets, with labels.
All the three inner terrestrial worlds were there: Venus, at top, Mercury below Regulus, and Mars lowest of the trio. Of course, a fourth terrestrial world is in the photo, too – Earth!

Mercury was at its greatest western elongation this morning, placing it as far from the Sun and as high in the sky as it gets, with this autumn appearance the best of 2017 for a morning showing for Mercury. Even so, you can see how Mercury is always low and easy to miss. However, this morning it was obvious to the naked eye.

Mars and Mercury will be in close conjunction at dawn on the morning of September 16.

Rocky Planets at Dawn (Sept. 12, 2017)

It was a fine morning to be up early and enjoy the solar system show.

— Alan, September 12, 2017 / © 2017 Alan Dyer / amazingsky.com

 

The Moons of Lost Sleep


Waning Moon in the Morning Series (with Labels)

These are the Moons only insomniacs and night shift workers get to see. These are the waning Moons of morning.

For eight mornings I’ve been up at 4 a.m. each day to catch the early Moon and collect a series of images of its waning phases.

The result is above, a series that runs from right to left in time, from the 19-day-old waning gibbous Moon, to the 26-day-old thin crescent Moon.

I ordered them that way in the composite to reflect the direction the Moon moves across the sky. As it orbits Earth and wanes, the Moon moves from west to east, or right to left, in the sky from morning to morning, at least in the northern hemisphere.

A run of clear nights and mornings made the series possible. From Alberta, as dry as it is, too many cloudy nights make a consistent Moon phase series a challenge at best.

As it was I had to contend with smoke from forest fires in B.C. which reddened the Moon on the last few mornings, a tint I had to correct for the composite above. But here below, is what the Moon really looked like one morning.

Smoky Waning Crescent Moon
The smoky orange Moon of July 17.

The last two Moons, at 25 and 26 days old (i.e. the number of days since the previous New Moon phase) exhibited the phenomenon known as Earthshine. You can see the night side of the Moon glowing gently with sunlight reflected first off the Earth.

Waning Moon and Earthshine (July 20, 2017)
Earthshine on the 25-day old Moon on July 20 at dawn.

Below, this was the Moon this morning, July 21, with it very low in the east amid the twilight sky.

Waning 26-Day Moon with Earthshine
Earthshine on the thin 26-day old Moon on July 21 at dawn.

This final morning was exceptional. The smoke had cleared off, and when I got up at 4 a.m. (reluctantly!) for the last shoot I was greeted with the best display of noctilucent clouds I had seen in many years. They covered the northeast and eastern skies in a rare “grand display.”

Noctilucent Clouds at Dawn with the Moon and Venus
Noctilucent clouds with the Moon and Venus in the dawn sky, from southern Alberta, July 21, 2017.

The thin crescent Moon is just rising at right, with Venus bright as a “morning star” at far right. This was a sky certainly worth losing sleep over.

— Alan, July 21, 2017 / © 2017 Alan Dyer / amazingsky.com

 

Rising of the “Strawberry” Moon


The Rising Strawberry Moon of June 9, 2017 (Composite)

The Full Moon of June rose into a twilight sky over a prairie pond. 

On June 9, the clouds cleared to present an ideal sky for capturing the rising of the so-called “Strawberry Moon,” the popular name for the Full Moon of June.

The lead image is a composite of 15 frames, taken at roughly 2.5-minute intervals and stacked in Photoshop with the Lighten blend mode.

The image below is a single frame.

The Rising Strawberry Moon of June 9, 2017
The rising Full Moon of June, dubbed the “Strawberry Moon” in the media, as seen rising over a prairie pond in southern Alberta, on June 9, 2017. This is a single exposure stack, from a time-lapse sequence of 1100 frames, with images taken at two second intervals. Shot with the Canon 6D and 200mm lens.
I set up beside a small local prairie pond, to shoot the moonrise over the water. Ducks enjoyed the view and a muskrat swam by at one point.

I shot over 1100 frames, at two-second intervals to create a time-lapse of the rising Moon, as it brightened and turned from yellow-orange (not quite strawberry pink) to a bright white.

Here’s the time-lapse vignette.

Click on HD for the best view.

While the Harvest Moon gets lots of PR, as this sequence shows any Full Moon can provide a fine sight, and look yellow, due to absorption of the blue wavelengths by the atmosphere as the Moon rises, or as it sets.

However, the timing can vary from Full Moon to Full Moon. This one was ideal, with it rising right at sunset. If the Moon comes up too late, the sky might have already darkened, producing too great a difference in brightness between the Moon and background sky to be photogenic.

But what of these Moon names? How authentic are they? 

Who called this the Strawberry Moon? Native Americans? No. Or at best only one or two nations. 

Check the site at Western Washington University at http://www.wwu.edu/depts/skywise/indianmoons.html and you’ll see there were an enormous number of names in use, assuming even this listing is authentic. 

The names like “Strawberry Moon” that are popularized in the media today come from the American Farmers Almanac, and everyone – science writers and bloggers – ends up copying and pasting the same wrong, or at best misleading, information from the Almanac. 

Search for “Strawberry Moon” or “Moon names” and you’ll find the same explanation repeated verbatim and unquestioned by many writers. Alas, the Almanac is not an authoritative source – after all, they were the source of a misleading definition of Blue Moon decades ago. 

Yes, people around the world may have long had names for months and moons, but they were not necessarily the ones that make the rounds of news sites and blogs today. Most are a modern media concoction. A few years ago, pre-internet, no one knew about nor used these names. 
— Alan, June 10, 2017 / © 2017 Alan Dyer / www.amazingsky.com