star cluster – The Amazing Sky

April 9, 2015

Heads Up! – Planets Pair with Clusters

Look west and south this weekend to see the two brightest planets each pairing with a bright cluster of stars.

This weekend, Venus and Jupiter each pair with a prominent open star cluster.

In the west, look for brilliant Venus, an evening “star” this spring, shining near the Pleiades, or Seven Sisters star cluster. Some know it as Messier 45.

Both Venus and the Pleiades are in Taurus the bull, whose main stars lie to the left of the Venus-Pleiades pairing. Farther to the left still, look for the distinctive stars of Orion the hunter, whose trio of Belt stars give him away.

As this close up shows, binoculars will nicely frame Venus and the Pleiades at once.

Venus continues to climb higher this spring while the Pleiades and the other stars of the winter sky, including Orion and Taurus, sink lower and lower. The next few nights are the best for catching Venus as it passes the Pleiades.

High in the south as it gets dark shines the other bright planet in our sky – Jupiter.

It, too pairs with a star cluster. Jupiter now shines a binocular field to the east (left) of the Beehive Cluster, also known as Messier 44. Jupiter and M44 lie in Cancer the crab, a faint constellation nestled between Leo to the east and Gemini to the west.

Jupiter has been retrograding closer to the Beehive all winter and early spring. But this weekend Jupiter sits as close to the cluster as it is going to get. For the rest of spring and summer Jupiter will move east away from the Beehive.

Look west and south as it gets dark this weekend, for the pair of planet-cluster pairings!

Clear skies and happy stargazing.

March 24, 2015March 24, 2015

Moon Amid the Hyades

The waxing crescent Moon shines amid the stars of the Hyades cluster.

I shot these on the evening of March 24 when, from western North America, the Moon appeared superimposed in front of the sprawling Hyades star cluster in Taurus.

The main image at top is with a 200mm telephoto lens and takes in most of the Hyades and the bright red star Aldebaran at lower left. Unfortunately, it also includes a blue lens flare from the brilliant and overexposed crescent, a tough element to “photoshop” out.

The image is a high dynamic range stack of 3 exposures. Even so, I purposely overexposed the Moon to bring out the stars and their colours.

This close up of the Moon includes fewer Hyades stars, but with the Moon centred I was able to avoid the lens flare. It’s an HDR stack of 5 exposures, to capture details in the sunlit crescent as well as on the dark side of the Moon lit by blue Earthshine.

These are the last telescopic shots from my winter in New Mexico, as the telescope and mount gets packed up tomorrow, in preparation for the trip back to Canada.

It’s been a fabulous winter of sky shooting, with some 500 gigabytes of images shot, processed, and archived!

January 18, 2015

Lovejoy Passes the Pleiades

Tonight Comet Lovejoy paired with the Pleiades star cluster.

Sunday, January 18 was the night to catch the ever-photogenic Comet Lovejoy at its best and closest to the Seven Sisters, the Pleiades. Its long blue ion tail stretched back past the Pleiades.

I thought the tail would be passing right over the star cluster, but not so. At least not when I was shooting it at about 7:30 pm MST.

Still, the combination made a fine pairing of cosmic blue objects for the camera. The top image is with a 135mm telephoto.

This wide-angle image, with a 24mm lens, takes in many of the northern winter constellations, from Orion at bottom, to Auriga at top, with Taurus in the middle. Notice the dark tendrils of the Taurus Dark Clouds.

At right, beside the Pleiades, is the green and blue comet, with its tail reaching back past the Pleiades.

I shot both images from the dark skies of City of Rocks State Park, New Mexico, which has proven to be one of the finest places on the planet for watching Lovejoy!

December 7, 2014December 7, 2014

Supernova Remnant & Star Cluster

A bubble of glowing gas blows away from an ancient dying star, next to a cluster of new stars in Gemini.

This image, from a week ago, captures contrasting stages in the life of a star.

At left is a crescent-shaped bubble of gas called IC 443, or the Jellyfish Nebula, billowing away from the site of an ancient supernova explosion, when a giant star ended its life in a blast thousands of years ago. Estimates put its age as between 3,000 and 30,000 years.

At upper right is the bright open star cluster, Messier 35, a gathering of hundreds of comparatively new stars at the beginning of their lives. M35 lies 2,800 light years away, close enough that its stars are nicely resolved in my photo and in any small telescope. M35 is one of the showpieces of the winter northern sky.

Just below M35 you can see a fuzzy glow. It’s another star cluster, NGC 2158. However, its great distance of 11,000 light years makes it appear as a small, partially-resolved glow, a nice contrast in clusters near and far.

This image focuses on IC 443, sitting between the stars Eta (right) and Mu Geminorum. The field is filled with other faint nebulosity, all part of the cycle of star birth and death.

November 19, 2014

The Seven Sisters in a Silver Braid

“Many a night I saw the Pleiads, rising thro’ the mellow shade,

Glitter like a swarm of fireflies tangled in a silver braid.”

– Alfred, Lord Tennyson

These are the famous Seven Sisters, the Pleiades, caught two nights ago in New Mexico skies. This bright star cluster stands out easily to the unaided eye in the winter sky, shining in the shoulder of Taurus.

What the eye does not see is the “silver braid” – the dim dust that surrounds the Pleiades. The stars light the dust, causing it to shine blue near the stars. Farther out, the dust is much dimmer and glows with pale tints of cyan and red.

The dust clouds were once thought to be what was leftover from the formation of the stars, now estimated to have occurred about 100 million years ago. However, current theory suggests that the natal dust of the Pleiads would have long since dispersed.

Instead, the silvery braids of dust that surround the Seven Sisters are just nearby dust clouds in Taurus that the stars are passing through, and illuminating with their hot blue light.

The Pleiades, as familiar as they are – they have been mentioned in ancient texts and myths dating back thousand of years – remain a source of scientific controversy. Astronomers argue over their distance, with different methods providing different results. But the best recent measurement puts them 440 light years away.

Technical notes: This is a stack of 10 x 12 minute exposures at ISO 400 with the Canon 5D MkII camera and 92mm TMB refractor at f/4.4. I shot the images November 16 from near Silver City, New Mexico.

November 18, 2014

Both the Heart and Soul of Cassiopeia

Here are both the heart and the soul of Cassiopeia the Queen.

Two days ago I posted an image of the Soul Nebula. Now, here is the matching Heart Nebula, in a mosaic of the glorious region of the Milky Way called the Heart and Soul Nebulas located in the constellation of Cassiopeia.

They are otherwise respectively called IC 1805 and IC 1848. Amid the swirls of nebulosity are numerous clusters of stars, such as NGC 1027 just above centre. The separate patch of nebulosity at upper right is NGC 896.

I shot the frames for this 3-segment mosaic over two nights, with one segment taken from the frames that made up the previous post. Plus I shot two others to span the region of the Milky Way that is about seven degrees long, a binocular field.

Each of the 3 segments is a stack of 12 frames, with each frame a 6-minute exposure. I used the filter-modified Canon 5D MkII and shot through the TMB 92mm apo refractor at f/4.4. All processing was in Photoshop, including the mosaic assembly.

In all, it’s the best image I’ve taken of this much-shot area of the sky. It really brings out the diversity in star colours, and sky colours, from the dusty orange-brown region at left, to the inky dark dustless region at far right.

November 9, 2014

Truly Interstellar

We gaze into the interstellar depths of the Milky Way through uncountable stars.

In this telescopic scene we look toward the Scutum Starcloud, and next spiral arm in from ours as we gaze toward the core of the Galaxy.

The field is packed with stars, seemingly crowded together in interstellar space. In fact, light years of empty space separate the stars, even in crowded regions of the Milky Way like this.

Two dense clusters of stars stand out like islands in the sea of stars. At lower right is Messier 26, an open cluster made of a few dozen stars. Our young Sun probably belonged to a similar family of stars billions of years ago. M26 lies 5,200 light years away.

At upper left is a condensed spot of light, made of hundreds of thousands of density packed stars in the globular cluster known only as NGC 6712. Though much larger and denser than M26, NGC 6712 appears as a tiny spot because of its remoteness – 23,000 light years away, a good part of the distance toward the centre of the Galaxy.

Look carefully (and it may not be visible on screen) and you might see a small green smudge to the left of NGC 6712. That’s a “planetary nebula” called IC 1295. It’s the blown off atmosphere of an aging Sun-like star. It’s what our Sun will become billions of years from now.

At top is a vivid orange-red star, S Scuti, a giant pulsating star nearing the end of its life.

A truly interstellar scene.

April 29, 2014

Splendid Southern Star Clusters

The southern Milky Way is populated by the sky’s best clusters of stars.

Here are three of the southern sky’s best star clusters, in portraits I took earlier this month from Australia.

At top, my main image takes in a great contrasting pair of star clusters. Both lie in the constellation of Puppis, once part of the ship Argo Navis.

At left is the stunningly rich NGC 2477, so packed with stars it almost ranks as a globular cluster, not one of the sparser open clusters. At least that’s the impression it gives in the eyepiece. But instead of containing hundreds of thousands of stars, as do globulars, NGC 2477 “only” has 300 stellar members. They are just very tightly packed in one of the richest open star clusters in the sky. If it had been farther north NGC 2477 would certainly rate as one of the top 100 sky sights, and carry some memorable name after a fanciful resemblance to who knows what! Instead, it carries but a catalog number.

Next to it, at right, is NGC 2451, more typical of open clusters. It has a central bright star, this one naked eye, surrounded by 40 or so lesser stars of contrasting colour and brightness. The two clusters make a great side-by-side comparison in any low-power telescope.

Much farther along the southern Milky Way is this rich open cluster (above), NGC 6067, in Norma, itself embedded in one of the richest star clouds of the southern Milky Way, the Norma Star Cloud. Here you are gazing for 6800 light years toward the cluster which shines suspended against the background of the even more distant inner arms of our spiral galaxy.

So NGC 6067 looks a little like an island of blue stars amid the dust-reddened background of more distant stars in the Milky Way — an island in a sea of stars.

April 4, 2014

The Milky Way of the Deep South

The Milky Way of the southern hemisphere contains some astonishing deep-sky sights.

The lead image above shows the section of the Milky Way that extends farthest south, and so is visible only from tropical latitudes in the north and, of course, from the southern hemisphere. I shot these images this past week in Australia.

The wide-angle image above takes in the southern Milky Way from Vela, at right, to Centaurus, at left. In the middle is the Southern Cross (left of centre), the Carina Nebula complex and surrounding clusters, and the False Cross at right of frame. The close-ups below zoom into selected regions of this area of the Milky Way. All are spectacular sights in binoculars or any telescope.

This image frames the left side of Crux, the Southern Cross. The bright stars are Becrux (top) and Acrux (bottom). Just below Becrux is the compact and brilliant Jewel Box cluster, aka NGC 4755. Below it are the dark clouds of the Coal Sack, which in photos breaks up into discrete segments and patches.

This region is a favourite of mine for images and for visual scanning in any telescope. The large nebula is the Lambda Centauri complex, also labelled the Running Chicken Nebula. Can you see its outline? Above it is the beautiful Pearl Cluster, aka NGC 3766.

This is the standout object in the deep south – the Carina Nebula complex. I’ve shot this many times before but this is my best take on it. At upper left is the Football Cluster, NGC 3532, while at upper right is the Gem Cluster, NGC 3293.

Seeing this area in person is worth the trip to the southern hemisphere. There are now many photographers up north who have shot marvellous images of Carina but using robotic telescopes. They have never actually seen the object for themselves. They print the images upside down or sideways, a sign of their detachment from the real sky.

You have to stand under the southern stars to really appreciate the magnificence of the Milky Way. All else is just data taking.

– Alan, April 5, 2014 / © Alan Dyer

October 12, 2013October 12, 2013

The Pleiades – The Stellar Seven Sisters

The stars of the Pleiades sit amid a dusty sky in Taurus.

These are the famous Seven Sisters of Greek legend, known as the Pleiades. They are the daughters of Atlas and Pleione, who are also represented by stars in the cluster. Many cultures around the world tell stories about these stars, but in Greek tradition their appearance signalled the summer sailing season in the Mediterranean. The Pleiades first appear at sunset in the eastern evening sky in autumn and put in their last appearance in the western sky in spring.

One story has it they were placed in the sky to recognize their devotion to their father Atlas and his unending labour in holding up the heavens. They are the half-sisters of the Hyades, another nearby cluster of stars in Taurus. Other stories describe the Pleiades as the Seven Doves that carried ambrosia to the infant Zeus.

A seldom-used name now for this cluster is the Atlantides, from the plural form of Atlas, their father. Thus, these sisters gave their name to the Atlantic Ocean, a vast and uncharted sea until the 16th century. The term “atlas,” first used by Mercator for a book of maps, comes not from the Pleiades’ father but from a real-life king in Morocco who supposedly made one of the first celestial globes.

I shot this portrait of the Sisters a few nights ago, stacking a set of five 15-minute exposures with the TMB 92mm refractor and Canon 5D MkII at ISO 800. I processed the image to bring out the faint clouds of dust that pervade the area.

The Pleiades are passing through dust clouds in Taurus and lighting them up. The stars are embedded in dust, lit blue by the light of the hot stars. But even farther out you can see wisps of dust faintly illuminated by the light of the Pleiades.

The stars are thought to be about 100 million years old, quite young as stars go. They formed together in a massive nebula that has long since dissipated, and will travel together for another few hundred million years until the sister stars go their own way around the Galaxy. The stellar family that gave rise to so many legends around the world will be scattered to the stars.

October 11, 2013

A Star-Filled Scene in Cassiopeia

A star cluster and nebulas highlight a glorious starfield in Cassiopeia.

I shot this three nights ago on a very clear autumn evening. The telescope field takes in the star cluster Messier 52 at upper left, a cluster of 200 stars about 5000 light years away. It is one of the best objects of its class for viewing in small telescopes. Charles Messier found it in 1774 as part of his quest to catalog objects that might be mistaken for comets.

The brightest area of nebulosity below M52 is the Bubble Nebula, aka NGC 7635, found in 1787 by William Herschel. It’s an area of star formation marked by a central bubble of gas (just visible on the scale of my photo) being blown by the winds from a hot central star. The Bubble can be seen in amateur telescopes but is a tough target to spot.

Above the Bubble is a small bright nebula, NGC 7538.

Below the Bubble lies a larger claw-like nebula known only as Sharpless 2-157, an object that shows up only in photos.

In all, it’s a complex and beautiful field, set in the constellation of Cassiopeia the Queen.

A footnote for the technically minded: This is a stack of 5 x 15 minute exposures with a filter-modified Canon 5D MkII at ISO 800 shooting through a TMB 92mm apo refractor at f/4.8, mounted on an Astro-Physics Mach 1 mount guided by a Santa Barbara SG-4 autoguider.

September 30, 2013

King and Queen of the Sky

Cassiopeia and Cepheus reign over the autumn sky amid the Milky Way.

This is a photo from last night’s shoot, taken on a very clear autumn night with the Milky Way prominent across the sky. I shot sets of constellation images, among them this one framing Queen Cassiopeia and King Cepheus.

Cassiopeia is the well-known “W” pattern at lower left. Cepheus is harder to pick out – he’s a crooked square at right, topped by a tall triangle, like a child’s drawing of a house.

The Milky Way runs across the frame, peppered with red nebulas, from IC 1396 at far right in the bottom of Cepheus, to the NGC 7822 complex at centre, and the IC 1805 complex at far left. Lots of smaller nebulas dot the scene. At far left is the Double Cluster, two adjacent clumps of stars in the outer Perseus Arm of the Milky Way. Most of the deep-sky objects in this frame lie thousands of light years away in the next spiral arm out from the one we live in, or in the space between the two arms.

Most of the bright stars here are young blue stars. But a couple of exceptions stand out: yellow Shedar (or Alpha Cassiopeiae, the bottommost star in the W and an orange giant), and red Mu Cephei, at far right bordering the round IC 1396 nebula. That star is also known as Herschel’s Garnet Star. It is a red supergiant star 1400 times larger than our Sun and one of the most luminous stars in the catalog.

February 14, 2013

A Luminous Starfield

The Starfish and the Flaming Star combine to create a rich star field in the Charioteer.

I shot this last week, using a favourite small refractor that takes in a generous field of view for a telescope. In this case, it frames the star cluster at left called the Starfish Cluster, or better known as Messier 38. At right the large number 7-shaped patch of nebulosity is the Flaming Star Nebula, known by its catalog number as IC 405. At bottom, the nameless companion nebulas are IC 417 at left and IC 410 at bottom centre.

Of note is the colourful grouping of six stars at right called the Little Fish. It’s not a proper star cluster but an asterism, a chance alignment of stars that happens to look like something imaginative. David Ratledge presents a nice list and photo gallery of similar whimsical asterisms at his Deep-Sky.co.uk website.

The entire field is a rich hunting ground for the eyepiece or camera. You can find it these nights, in winter from the northern hemisphere, straight overhead in the evening, in the middle of Auriga the Charioteer.

For this portrait I shot and stacked eight 7-minute exposures at ISO 800 using a filter-modified Canon 6D on my TMB 92mm apo refractor at f/4.8.

Happy Valentine’s Day!

February 7, 2013February 10, 2013

Snapshots of Starlife

This one image frames examples of both the beginning and end points of a star’s life.

I shot this last night, February 6, 2013, capturing a field in the constellation of Gemini the twins. At upper right is the showpiece star cluster known as Messier 35. It’s a collection of fairly young stars still hanging around together after forming from a cloud of interstellar gas tens of millions of years ago. M35 lies about 2,800 light years from Earth, on the other side of the spiral arm we live in. Just below M35 you can see another smaller and denser cluster. That’s NGC 2158, about five times farther away from us, thus its smaller apparent size. Both are objects that represent the early stages of a star’s life.

At lower left is an object known as the Jellyfish Nebula, for obvious reasons. The official name is IC 443. It’s the expanding remains of a star that blew up as a supernova anywhere from 3,000 to 30,000 years ago. What’s left of the star’s core can still be detected as a spinning neutron star. You need a radio telescope to see that object, but the blasted remains of the star’s outer layers can be seen through a large backyard telescope as a shell of gas. It is expanding into the space between stars – the interstellar medium – ploughing into other gas clouds. The shockwave from its collision with other nebulas may trigger those clouds to collapse and form clusters of new stars. And so it goes in the Galaxy.

For this portrait of stellar lifestyles, I used a 92mm apochromatic refractor and a new Canon 6D camera, one that has had its sensor filter modified to accept a greater range of deep red light emitted by hydrogen nebulas. The image is actually a stack of 12 exposures with an accumulated exposure time of 80 minutes.

December 27, 2012December 27, 2012

Canis Major and the Dog Star

Shining in the southern sky these nights are the stars of Canis Major, the big hunting dog of Orion the Hunter. Among them is the famous Dog Star, Sirius, the brightest star in the night sky.

Can you see a dog outlined in stars? Sirius marks his head – or it is sometimes depicted as a jewel in his collar. His hind legs and tail are at the bottom of the frame.

I shot this earlier this month from Australia, where Sirius and Canis Major stand high overhead. From northern latitudes you can see these stars due south low in the sky about midnight. Sirius is hard to miss, often sparkling through many colours as our atmosphere distorts its light. But as the photo shows, it is really a hot blue-white star. While it is intrinsically a bright star, much of its brilliance in our sky comes from its proximity, only 9 light years away from us.

For this portrait of the celestial canine I used a 50mm “normal” lens. The atmosphere provided some natural haze this night, to add the glows around the stars accentuating their colours.

This area of sky also contains several nebulas, notably the red arc of the Seagull Nebula to the left of Sirius. Below Sirius you can also see the star cluster Messier 41, a good target for binoculars.

Toward the left edge of the frame you can see a pair of star clusters, Messier 46 and Messier 47, two other excellent binocular objects in the Milky Way, which runs down the frame to the left of Canis Major. The dog is just climbing out of the Milky Way after a swim in this river of stars.

October 15, 2012October 16, 2012

Jupiter Rising

Look east now late at night and you’ll see Jupiter rising amid the stars of Taurus.

I took this shot a week ago from my rural backyard on the last clear night I’ve had. Remarkably, I had bought a new camera – a Canon 60Da – earlier that day and was actually able to try it out. This is the first real shot I took with it. It shows Jupiter amid the horns of Taurus the bull, and below the Pleiades. A faint aurora lights up the northern sky at left.

There have been some superb aurora displays in the last week but clouds just got in the way.

This is my 200th blog post since I began AmazingSky.net in early 2011. I hope you have enjoyed the images and will continue to do so. Thanks for looking!

September 25, 2012September 25, 2012

Star Birth Site

In contrast to last Saturday’s post, Star Death Site, this is a place where stars are born.

This magenta cloud is where dozens of new stars are forming. One centre of star formation is the finger at right jutting into the hollowed out core of the nebula. Ultra-violet radiation from nearby hot stars is eroding away this dark finger of dust and gas, causing its rim to glow. This is a feature similar to the famous “Pillars of Creation” depicting in Hubble Space Telescope views of another nebula, the Eagle Nebula. However, this giant wreath of hydrogen 3000 light years away has no name, just the catalog number IC 1396. It’s in Cepheus, high in the northern autumn sky.

An added attraction of the scene is the orange star at top, Herschel’s Garnet Star, a.k.a. mu Cephei. This red supergiant is one of the largest stars known. If it replaced our Sun the Garnet Star would engulf all the planets out to Jupiter. Including its profuse radiation emitted in the infrared, the Garnet Star outshines the Sun by 350,000 times. It is squandering its energy so quickly this supergiant is destined to explode as a supernova, perhaps leaving behind a remnant like the Veil Nebula I described in that earlier blog from a few days ago.

These deep space wonders are all part of the great cycle of stardust that fuels the Galaxy.

August 9, 2012August 9, 2012

A Cloud of Stars in Scutum

This is a binocular-sized gulp of sky in the northern summer Milky Way. Countless stars form a bright patch in the Milky Way called the Scutum Starcloud, named for the odd little constellation of Scutum the Shield that contains it.

Visible to the naked eye, this star cloud is a rich area for binoculars or a small telescope. One favourite object of stargazers lies embedded in the star cloud and can be seen here as a bright clump of stars at left of centre. That’s the Wild Duck Cluster, or Messier 11, a dense and populous cluster of stars within the already star-packed Scutum Starcloud. Look in this direction into the Milky Way and you are looking toward the next spiral arm in from ours, some 6,000 light years away.

The immensity of stars in just this small area of sky is hard to fathom. That’s why it’s called deep space!

January 29, 2012January 29, 2012

Celestial Pinks and Blues

Who says the dark night sky isn’t colourful? Of course, to the naked eye it mostly is, with the darkness punctuated only with a few red, yellow and blues stars. But expose a camera for long enough and all kinds of colour begins to appear.

This region is above us now, in the Northern Hemisphere evening sky for mid-winter. It’s the boundary area between Taurus and Perseus. Below are the vivid blues of the hot young Pleiades star cluster in Taurus. At top, just squeezing into the frame, is the shocking pink of the California Nebula, a glowing cloud of hydrogen gas in Perseus.

But between are the subtle hues of faint nebulosity weaving all through the Perseus-Taurus border zone. Below are faint cyans and blues from dust clouds reflecting the light of the Pleiades stars. In the middle are the yellow-browns of dark dust clouds hardly emitting light at all, but snaking across the frame to end in a complex of pink and blue straddling the border collectively known as IC 348 and IC 1333. At top, the glowing hydrogen gas of the California emits a mix of red and blue wavelengths, creating the hot pink tones, but fading to a deeper red to the left as the nebula thins out to the east. Throughout, hot blue stars pepper the sky and help illuminate the dust and gas clouds which will likely form more hot stars in the eons to come.

I took this shot last Wednesday night, on one of the few clear, haze-free nights of late. This is a “piggybacked shot,” with the Canon 5D MkII camera going along for the ride on one of my tracking mounts. This final shot is a stack of five 6-minute exposures, highly processed to bring out the faint clouds barely brighter than the sky itself. The camera was equipped with a 135mm telephoto lens, giving a field of view a couple of binocular fields wide. Hold out your hand and your outstretched palm would nicely cover this area of sky. But only the camera reveals what is actually there.

June 16, 2011June 16, 2011

Into the Heart of the Scorpion

Here we peer into the heart of Scorpius, to a place where the sky is painted with pastel hues unlike anywhere else in the heavens.

The yellow star at bottom is Antares, the cool supergiant star that marks the heart of the Scorpion. To the right is Messier 4, a globular cluster of thousands of stars. Wrapping the entire field are shrouds of dust, reflecting the yellow light of Antares and the blue light of hotter stars above, such as Rho Ophiuchi at top right. Glowing hydrogen gas clouds add the magenta hues.

The remarkable feature of this field are the dark fingers, clouds of dark interstellar stardust glowing with a dim yellowy-brown hue. In places the clouds become more opaque and intense, blocking any light from background stars. Those clouds must be close by in our galactic spiral arm because few stars lie between us and their dark masses. Estimates put them about 400 light years away.

The entire region is a busy factory of star making, one of the closest to our Sun. Chances are our solar system formed in a similar star factory 5 billion years ago, one that has long since dissolved away and dispersed around the Galaxy.

Like the previous shot, this is a Canon 7D/135mm telephoto image in a stack of six 2-minute exposures, taken from Chile in early May. I find it remarkable that with digital cameras just 2-minute exposures not only bring out the dark nebulas, but actually show them with colour and tonality. In the old days, film shots 20 minutes long only ever showed them as a mass of underexposed and featureless black.

June 16, 2011

Off the Stinger Stars of Scorpius

Off the tail of Scorpius lies one of the great starry regions of the Milky Way. From southern Canada the Scorpion’s Tail barely clears our horizon at this time of year, on June nights. But from farther south, Scorpius crawls high into the sky — and the sky actually gets dark at solstice, so stargazers can see the starclouds of Scorpius in all their glory.

At right, the blue stars mark the “stinger” at the end of the Scorpion’s tail. The brightest one, called Shaula, or Lambda Scorpii, is a hot blue giant star some 10,000 times more luminous than our own modest Sun. It is also a triple star, with another luminous blue star orbiting it, plus a third odd mystery star thought to be either a neutron star or perhaps a young proto-object still in the process of forming a proper “main-sequence” normal star.

To the left lie two prominent clusters of stars: at top the Butterfly Cluster (a.k.a. Messier 6), a bright group of stars sitting amid a dark bay of dust. Below it, almost lost in the stars, is Ptolemy’s Cluster (a.k.a. Messier 7), that is an obvious sight to the unaided eye – so obvious the Greek astronomer Ptolemy catalogued it in 130 AD. Several other star clusters pepper the field.

This telephoto lens shot frames the field as binoculars would show it. I took this from Chile in early May, using the Canon 7D and 135mm lens, for a stack of six 2-minute exposures at f/2.8 and ISO 1250.

June 7, 2011

A Window in the Stars

In this part of the sky the Milky Way takes on a surprising palette of hues. And it’s all due to dust.

The centrepiece of this shot is a bright star cloud in Sagittarius called, well, the Sagittarius Star Cloud! But not the Large one. This is the Small Sagittarius Star Cloud, a.k.a. Messier 24, a mass of stars with a single black eye. The dark spot, called Barnard 92, is a dense and opaque cloud of dust. Stardust — clouds of carbon soot blown out by aging stars — weaves all through this scene, creating the dark canyons winding through the stars. Obscuring dust also dims much of the background stars and discolours most of this part of the Milky Way a yellowish brown. It’s the same effect that dims the setting Sun a deep orange or red, as its light shines through haze and dust in the sky.

But here, the Star Cloud looks bluish and “cleaner.” That part of the Milky Way has less dust in front of it. And yet it is much farther away than the yellow dusty starfields around it. When we look toward the Small Sagittarius Star Cloud we are looking through a dust-free window, allowing us to see unencumbered right past our Galaxy’s nearby Sagittarius-Carina spiral arm to glimpse a dense part of the more distant Norma Arm, an inner spiral arm of our Milky Way Galaxy about 12,000 to 16,000 light years away.

To the lower right of M24 is M23, a rich cluster of stars 2,000 light years away, nearby by galactic standards, and so sits suspended in front of the fainter star background. The pinkish nebula at top is Messier 17, the Swan Nebula.

I took this shot May 2 from Chile, using the Canon 7D and 135 lens, for a stack of six 2-minute exposures.

June 4, 2011

The Seven Sisters of the South

Down in the south sit many austral equivalents to namesake northern sky objects: the Southern Cross, the Southern Beehive, the Southern Pinwheel. This is the “Southern Pleiades,” a match to the famous Pleiades star cluster prominent in our northern hemisphere sky. Since our Pleiades also carries the moniker the “Seven Sisters,” I suppose that makes this object the “Seven Sisters of the South.”

The field here again duplicates what binoculars would show, and this is a lovely object for binos. Its resemblance to the northern Pleiades comes from this star cluster’s bright but scattered appearance, and the blue colour of its sorority of stars. Like its northern counterpart, the Southern Pleiades is a cluster of hot young stars which shine furiously blue in their energetic youth. This group is perhaps no more than 50 million years old, and like the northern Sisters, shines quite close by, just 480 light years away, putting it a stone’s throw away down our own galactic spiral arm.

Officially catalogued as IC 2602, and also dubbed the Theta Carinae Cluster, this clutch of blue stars shines just below the Carina Nebula (you can see both together in my earlier blog The Best Nebula in the Sky). A couple of other fainter star clusters also populate the field.

I took this shot with the Canon 7D and 135mm telephoto lens and stacked five 2-minute exposures. Stacking helps smooth out background noise, though in a wide field shot like this, the sheer number of stars tends to overwhelm any camera noise.

June 4, 2011

An Island in a Sea of Stars

This image looks toward the inner spiral arm of our Milky Way called the Norma Arm, where stars bunch together to form the rich Norma Starcloud, a prominent patch in the southern Milky Way. What you see here is all stars, lots and lots of stars.

Seemingly embedded in the sea of stars is an island of brighter stars called the Norma star cluster, or more prosaically NGC 6067. It’s about 6800 light years away, much closer to us than the more distant stars behind it. It is literally floating in front of the background sea of stars.

As with the previous image, this is a wide field shot, taken with the 135mm telephoto, to frame the field much as it would appear in binoculars. This shot is a stack of six 2-minute unguided exposures at ISO 1250 with the Canon 7D riding on the little Kenko tracking platform. It’s one of a couple of dozen fields I shot the first night of shooting on Chile in May.

June 3, 2011June 3, 2011

Rose of the Southern Sky

It’s been a month since my last post, a month with no new astrophotos from home. But I’ve got a backlog of RAW files to work through from the Chile trip a month ago. Here’s a new image from that shooting expedition. It’s of an area of the southern sky that lends itself to every focal length and framing variation — you can’t go wrong with the Carina Nebula!

This wonderful nebula in the deep-south Milky Way rewards any astrophotographer. For this shot I used a 135mm telephoto (Canon’s wonderful f/2 L-series lens) and the Canon 7D camera. The 7D is what I call a “stock” camera, used just as it comes off the dealer shelf. The 7D does a superb job capturing the red nebulosity and its faint outlying bits and pieces. It tends to record these clouds of glowing hydrogen as magenta in tone. By comparison, my other Canon camera is a “filter-modified” 5D MkII. You can see a shot of this same area of sky taken with the 5D MkII a few blogs back under The Best Nebula in the Sky, posted May 6. The 5D MkII’s modification (which replaces the filter in front of the sensor with a new astro-friendly one) allows it to record deep-red wavelengths and picks up more faint nebulosity, registering it more as red in tone. But both images look good and presentable.

This field is rich in objects — not only the main sprawling nebula but nearby star clusters and patches of dark dust clouds. It is one of the finest fields in the sky for binoculars, and this shot approximates the field of view of typical binos. I like to shoot a lot of objects with telephoto lenses — while the main subject is not frame-filling and in your face, it does match (at least in field of view) what you can see in binos, useful for illustrations and observing articles. Of course, the camera picks up more stuff and colours even your bino-aided eyes can’t see.

This shot is a stack of five 2-minute exposures at f/2.8 with the 135mm telephoto, on the Canon 7D at ISO 1250. I used the little Kenko Sky Memo tracking platform for this, letting it track without any added guiding. It’s tracking was spot on, with nary any star trailing as it followed the target for 20 minutes or so.

May 3, 2011

Entangled in Dark Dust

This is a star cluster in Scorpius called NGC 6124 – it doesn’t have a name, to the best of my knowledge. But a good one might be the “Dark River Cluster.”

I’ve shot lots of stuff along the Milky Way on my various trips to the southern hemisphere, but this field was a pleasant new surprise. While I had photographed this star cluster before, previous portraits had been extreme closeups. I had not shot it with a wide field like this.

The field here takes in about the same area of sky as binoculars. One of my projects on this current trip to Chile has been to shoot binocular fields like this. And it’s a good one. The cluster is a little off the beaten track in Scorpius and tends to be ignored. But its position entangled with lanes of dark nebulosity makes it a wonderful contrast of stars and darkness.

The dark lanes are obscuring dust in the foreground, hiding the light of distant stars in the Milky Way. The cluster itself is about 18,000 light years away, quite a distance for a star cluster, and putting it a good portion of the way toward the centre of the Galaxy.

For this shot I used the Canon 7D camera and 135mm telephoto, for a stack of six 2-minute exposures at ISO 800 and f/2.8.

April 25, 2011

Springtime Cluster #3: Diamond Tresses in the Sky

Unlike most deep-sky objects, this one is obvious to the unaided eye. The Coma Star Cluster is so big it barely squeezes into the frame of the wide field telescope I used to take this image. To see it for yourself just look up and due south on northern spring evenings. To the left of Leo, off his back end, shines this loose and scattered grouping of stars obvious to the unaided eye on a dark night. Indeed, I think in olden times this bunch of stars was drawn as the tuft of hair at the end of Leo’s tail.

But now we picture this cluster of stars as the tresses of hair of the late dynasty Egyptian Queen Berenice II, placed in the sky to honour her loyalty to her husband, the Pharaoh Ptolemy. The story has it that the group did not become officially recognized as a constellation until the 16th century.

The constellation of Coma Berenices (hair of Berenices) extends over a larger area of sky than just this grouping, but the Coma star cluster is certainly the most obvious feature of the constellation. Binoculars frame it well (taking in a bit more sky than this image) and are the best way to view it. With their narrow field, telescopes look right through this object.

The cluster is spread over nearly five degrees of sky and contains about 40 stars, so a rather sparse gathering to be sure. Many open clusters, like M67 pictured a couple of blogs back, contain hundreds of stars. Coma is so big in our sky because it is one of the closest star clusters to us, only 288 light years away, and above us toward the north pole of our Galaxy.

Its size and scattered appearance actually meant it hid in plain sight for centuries – yes, it was given a name and people saw it, but astronomers didn’t give it status as an official star cluster until 1938. In 1915 astronomer P.J. Melotte had listed it as object number 111 in his catalogue of star groupings. And so today, we usually refer to this cluster as Mel 111, the most famous entry in “Mel’s” catalog!

I took this shot with the same gear used for the M67 and Beehive M44 shots earlier, so it’s easy to see just how much bigger the Coma Cluster is than just about every other star cluster in the sky. This is a stack of four 6-minute exposures at ISO 1600 with the Canon 7D camera and the 92mm TMB apo refractor.

April 24, 2011April 24, 2011

Springtime Cluster #2: Ancient M67

Poor old M67. Does anyone ever look at this cluster? I tend to ignore it, in favour of its brighter and bigger brother, the Beehive Cluster just to the north. Yet, this smaller cluster ranks with the best of the sky’s open star clusters for richness and brilliance. Only a few showpiece star clusters, like the Beehive and the Pleiades, beat M67.

Located in Cancer, M67 really deserves more respect – even a name! – as it stands out as one of the few prominent deep-sky objects in the otherwise sparse spring sky, at least sparse for bright targets for binoculars or a small telescope. Yes, if you love galaxies, the spring sky is heaven! There are thousands of galaxies to hunt down in spring, but most need a decent-sized telescope to do them justice. By contrast, M67 looks just fine in a small telescope. With a few hundred stars packed into an area the apparent size of the Full Moon this is one rich cluster.

M67 is called that because it is #67 in Charles Messier’s catalog of “things not to be confused as comets.” Messier came across this object in April 1780. Messier ‘s object #67 is one of the few open star clusters not embedded in the Milky Way. Like the Beehive, M67 sits well above the disk of our Galaxy’s spiral arms. We look up out of the plane of the Galaxy to view M67, sitting some 2600 light years away, over four times farther away than its neighbour in Cancer, the Beehive. Thus, M67 looks smaller than the Beehive because it is more distant.

M67 holds the distinction of being one of the oldest star clusters known. It’s been around for over 4 billion years. Its position well above the frenzied traffic jam of our Galaxy’s spiral arms helps M67 stay intact and together, an isolated island of stars in our spring sky.

This image was taken right after the M44 Beehive Cluster shot featured in my previous blog post, using the same gear. So the image scale is the same. You can see how much smaller M67 appears than M44. Because M67 was beginning to sink into the west when I took this, I bumped the camera up to ISO 1600 and used shorter 3 minute exposures and stacked five of them to smooth out noise. The telescope was the little 92mm TMB apo riding on the Astro-Physics 600E mount and flawlessly autoguided with the Santa Barbara Instruments SG-4 autoguider. I really love the SG-4 — just press one button and it’s guiding. True “Push Here Dummy” guiding!

April 23, 2011April 24, 2011

Springtime Cluster #1: The Beehive (M44)

At last! A clear night in what so far has been an awful spring. The long-awaited arrival of mild spring nights brings a sky sprinkled with a few naked-eye star clusters. This is the most famous, and appears as a fuzzy glow in the constellation of Cancer the Crab. Indeed, to the unaided eye, there’s not much else to see in Cancer. But this cluster is a dandy in binoculars. Called the Beehive, this is one of the few deep-sky objects known since antiquity. Apparently, the Greek poet Aratos mentioned it in 260 B.C., describing it as a “little mist.” A hundred years later Hipparchus included it in his star catalog, calling it a “cloudy star.”

It wasn’t until 1609 that Galileo, using his pioneering telescope, resolved the cloud into a mass of stars. Any binoculars will do the same today. This close-up view more closely matches the view through a modern telescope, showing its subtly coloured blue and yellow stars.

In 1769 Charles Messier included it as object #44 (the Pleiades was #45) in his first catalog of what we now call deep-sky wonders. To him, however, these fuzzy spots in the sky were just distractions to his goal of hunting the fuzzy things that really mattered – comets.

The stars of M44 really do belong together in a gravitationally-bound cluster of up to 1000 stars, traveling together through space since the time about 600 million years ago when they formed out of what must have been a massive gas cloud. That’s a pretty good age for a star cluster; most break apart and scatter around the Galaxy after just a few tens of millions of years. However, the Beehive sits about 600 light years away, above the main disk of the Milky Way and its spiral arms. Its location makes it partly immune to the disruptive tidal forces of the Galaxy. Because it lies above the galactic plane we see it far off the band of the Milky Way, shining in our spring sky sparsely populated with bright stars and lacking the rich assortment of clusters and nebulas scattered along the winter and summer Milky Way.

For this exposure I used a favourite scope, the TMB 92mm apo refractor, a compact and fast little telescope perfect for imaging big binocular-class objects like this. This is a stack of four 4-minute exposures at ISO 800 with the Canon 7D camera. A Photoshop routine added the diffraction spikes, purely for photogenic value.

February 21, 2011February 21, 2011

Hazy Hyades

Here’s a photogenic rendering of a classic northern winter sky object, the Hyades star cluster in Taurus. The Kenko Softon filter added the star glows and punched out the subtle colour variations in the stars. Note how the Hyades stars come in shades of blue and white. The yellow star is Aldebaran, the eye of Taurus the Bull and an interloper here — Aldebaran is actually halfway between us and the Hyades, which lie about 150 light years away, and are true cluster of stars moving together through space. Note the much more distant and smaller star cluster, NGC 1647, at left.