Orion & The Seven Sisters – StarLog_12/25/2014

Over Christmas night there were clear skies in Oklahoma and I was able to try my hand at some real astrophotography.  Messier objects are famous in the world of amateur astronomy and make up the best examples of the five types of deep sky objects (DSOs): diffuse nebulae, planetary nebulae, open clusters, globular clusters and galaxies.  The French astronomer Charles Messier was a renowned comet hunter who was frustrated by objects in the night sky that were not comets, so he made a list of everything the he deemed a distraction.  His catalog was completed in the late 1700s and contains over 100 astronomical objects.  The other night I took my first pictures of M42 and M45.

M42 also known as the Orion Nebula is a diffuse nebula in the constellation Orion.  After the Big Dipper, it ranks as the second most distinctive constellation in the night sky.  During the winter Orion, the mythical hunter, takes center stage in the southern skies.  Orion’s belt is what allows the star group to be so recognizable, nowhere else in the nights sky are three bright stars so well aligned.

Orion’s Belt and the Orion Nebula (M42) shot on a tripod using my Canon EOS Rebel T5i, EF 70-300 mm f/4-5.6 IS USM, f/4.0, 15 sec, ISO 800 in southern Oklahoma.

 

My first photograph contains the lower half of the constellation Orion.  The three bright stars in alignment seen in the upper left make up Orion’s belt.  Where as the pink diffuse nebula in the center is M42, also known as the Orion Nebula. 

Close up of the Orion Nebula (M42) shot on a tripod using my Canon EOS Rebel T5i, EF 70-300 mm f/4-5.6 IS USM, f/5.6, and 6.0 sec, ISO 1600 in southern Oklahoma.

The pinkish blur in the center of Orion is the real gem.  M42 is so cool because it is in the same arm as us in the Milky Way Galaxy but happens to be 1,344 light years distant.  This diffuse nebula is a stellar nursery and is one of the best examples of star birth.  Also, this stellar nursery is BIG, 24 light years across big.  The bright center contains a very young open cluster, known as the Trapezium.  This tight cluster of stars is responsible for much of the illumination in the Nebula.  As a whole, M42 contains more than 2,000 stars.  If you let your eyes adjust on a dark night you should be able to see this great cloud of gas and dust with your naked eye.

Working your way north from Orion leads you to another stellar wonder, the Pleiades, or the Seven Sisters (M45).  This open star cluster is one of the closest to us and being so makes it the most visible to the naked eye.  The Pleiades have had some sort of impact on almost all cultures going back to antiquity.  They were even used as a sort of ancient eye exam; it was a sign of keen eyesight if you could resolve at least seven of the stars.

The Pleiades, or the Seven Sisters (M45) shot on a tripod using my Canon EOS Rebel T5i, EF 70-300 mm f/4-5.6 IS USM, f/4.5, and 10.0 sec, ISO 1600 in southern Oklahoma.

 

Motion blur of the Pleiades, or the Seven Sisters (M45) shot on a tripod using my Canon EOS Rebel T5i, EF 70-300 mm f/4-5.6 IS USM, f/4.0, and 15.0 sec, ISO 1600 in southern Oklahoma.

  

The cluster is roughly 16 light years in diameter and contains over 1,000 confirmed stars.  Forming within the last 100 million years it is thought that the cluster was formed from a compact stellar cloud of gas and dust similar to the Orion Nebula.  Located only a short 440 light years away we can expect to have a clear view of this stellar wonder for another 250 million years before they rip themselves apart under the force of their own gravity.

Basic layout and structure of our region of the Milky Way Galaxy.  The Sun is located in the outer regions of the Orion Arm and the Orion Nebula is located south east of the sun while the Pleiades is located just south of the sun. Image taken from Terence Dickinson’s Nightwatch: A practical Guide to Viewing the Universe.

Photographing the Moon - StarLog 12/08/2014

Oklahoma has been foggy and overcast these past few weeks, but a few days ago there was a break in the weather and I was able to try out a new lens I got for my new digital single-lens reflex (DSLR) camera.  I was very happy with the image I was able to resolve and I learned something interesting when I decided to share the image with my friends and family.  What I learned was that most people cannot appreciate a good moon pic when they see one!  This is not to say that my photograph is a top-notch moon pic but I would like to explain how I took it to shed a little light on the effort needed to capture pictures of subjects that are 238,900 miles away from the sensor in your camera…

High resolution image of the moon shot on my Canon EOS Rebel T5i, EF 70-300 mm f/4-5.6 IS USM, f/11.0, 1/125 sec, ISO 200 in the parking lot outside my apartment on 12/8/14, 12:35:25 PM.

 

 

To wrap your head around how far away the moon is next time you find yourself outside under a full moon extend your arm to its full length and put your pinky finger in front off the moon.  Your pinky finger will cover almost exactly 1-degree of the night sky; the moon is about a half a degree across.  This shows that the moon is really actually very small; it only seems so big because everything else in the night sky is so much smaller.

The equipment that I used to capture the image include my Canon EOS Rebel T5i DSLR, EF 70-300 mm f/4-5.6 IS lens, a small tripod and an intervalometer as a remote shutter release.  Because of the distance and brightness of the moon I had to manually control the settings on the camera and lens to bring the moon into focus.  There is some skill in bringing a subject into focus in the cameras manual setting.  The three basic variables to the camera include aperture, shutter speed, and ISO.

Digital Single Lens Reflex (DSLR) Camera diagram. Source.

Aperture controls the amount of light that reaches the camera’s sensor.  It functions similar to the iris in our eyes by acting as a variable hole or window by which light can travel through.  If the aperture is narrow, then highly collimated (parallel rays of light) rays of light are focused on the cameras sensor resulting in a sharp image.  A wide aperture allows for light rays that are un-collimated to reach the sensor resulting in a less sharp image.  Aperture is measured as a series of f-stops that is the ratio of the focal length of the lens to the diameter of the aperture.  For example, if you’re using a 50mm lens and set the aperture to f/2, the diameter of the aperture will be 25mm.  In my case I was using a 300mm lens and used an f-stop of f/11.0 making the diameter of my aperture 27.27mm.   

Diagram of aperture by f-stop value. Source.

 

The shutter speed controls the amount of time the shutter will allow light to remain on the sensor.  This is measured in seconds and fractions of a second, or in the case of long exposures (required by most astrophotography) any amount of time so long as the camera is charged.  Because the moon acts as a mirror that reflects sunlight it is very bright and requires a fast shutter speed.  I used my benchmark as 1/1000 sec but cut it down to 1/125 sec for my image.  This short shutter speed is why the background is completely black, had I used a longer exposure some stars might have been able to accumulate in the image.

Diagram showing the effect of decreasing the shutter speed on a moving object.  Source.

   

ISO is the sensor sensitivity and determines the level of sensitivity of the camera to available light.  The lower the ISO number (ISO 100), the less sensitivity your camera will be to the light , this would be appropriate for a sunny day.  While a higher ISO number (ISO 3200) increases the sensitivity of your camera, this would be useful in low light conditions without the use of a flash.  In the case of my image I used a low ISO of 200 to reduce the graininess or “noise” that accompanies higher sensitivity.

Sectioned off image showing the effect of increasing sensor sensitivity.  Source.

 

So in summary I used a 300mm lens, with a narrow aperture of f/11.0, a fast shutter speed of 1/125 sec and a slow sensor sensitivity of ISO 200.  I was able to choose these settings because of a unique live view mode that my camera has built in.  This live view mode allows me to make certain adjustments to the camera and see a real time image of what the sensor will most likely reproduce.  In addition to this I manually focused the camera lens by zooming into the image and focusing the camera ring until the craters were crisp in the liquid crystal display (LCD) screen.  It was only then that I was able to tell the remote shutter to take the picture.  But I was not done yet.

I shot the picture using a camera raw image file that contains minimally processed data acquired from the camera’s image sensor.  This file has not yet been processed and allows for digital processing without adding to the original image.  All I did to my file was tweak the whites and blacks, shadows and contrast to really show the difference in surface features (lava fields = dark, regolith = light).  Then I slapped the file into Photoshop where I cropped the image to keep a high pixel density (prevent image blurring).  In the end the picture went from this:

The very over exposed image captured when using the cameras recommended settings.

 To this:

Image captured in manual mode before tweaking the raw file and cropping the image.

To a professional quality image:

An image that is not only visually stunning, but one that brings into focus another world.  The photograph resolves impact craters, lava fields, and even the very patch of land where man first walked on the moon!  It is really exciting how accessible high-level technology is becoming and with advances in optics and camera technology the sky is no longer the limit.

 

Full Lunar Eclipse - StarLog 10/08/2014

I decided to leave my large astronomy binoculars (25x100) back at my apartment because my well is going to be finishing up within the next couple of days and I figured I wouldn’t have an immediate need for them.  Turns out I was wrong. Shortly after unpacking my things from the truck I got a notification from Starwalk (an astronomy application) telling me that there was going to a full lunar eclipse tonight…
  

Time lapse of last night's lunar eclipse.

Fortunately you do not need highly sensitive optics to view the moon so I was content with my small pair of binoculars.  When the time came and the moon began to pass into the Earth’s shadow I stopped working, pulled up a lawn chair and sat back to enjoy the view.  I was within the region of the US that was able to get a clear view off the full eclipse and my skies were clear so I was very pleased with my view.  Earlier in the year during the last lunar eclipse a couple of friends and I drove an hour out of town in a snow storm in an attempt to catch a view of the eclipse.  Our outing ended in disaster when my friend’s car blew a head gasket, overheated and left us stranded.  We never caught so much as a glimpse of the event.  
  

While I was watching the moon pass into the Earth’s shadow I sent a text message out to a few friends and my family which was along the lines of, “If you’re awake there is a full lunar eclipse happening right now!”  As it so happened my Mom was driving to work and had a view through her front window, she called me up to talk about it.  Apparently they were talking about it on the radio, but my mom wondered why the moon turned red when in the presence of the Earth’s shadow.  I thought about it for a second and then I realized I wasn’t sure.  I figured that it had to do with the visible light spectrum and the differing wave lengths.  I gave a quick explanation of why the sky was blue and how that phenomenon could be explained by the scattering of the shorter blue wavelengths but I was still somewhat puzzled myself by why the moon was red.  If the moon is in the Earth’s shadow then the Moon must not be reflecting any of the light emitted from the Sun, right?  Wrong!  After doing a bit of research I realized that I was on the right track but I forgot to consider how light refracts or bends when it goes through a given medium such as the Earth’s atmosphere.
  

The celestial geometry of the Sun, Earth and Moon during a full lunar eclipse.

A full lunar eclipse is when the Sun, Earth and Moon are in perfect alignment and the Moon passes through the Umbra (or Earth’s shadow).  A normal argent full moon is very bright because it is reflecting direct sunlight back to Earth.  However, during a lunar eclipse it is no longer reflecting direct sunlight, but instead it is reflecting sunlight that has traveled through the Earth’s atmosphere and been refracted at a slight angle so that it hits the Moon.  
 

The visible light region of the Electromagnetic Spectrum.

A cartoonist’s recreation of Newton’s experiment in 1665 showing how a prism bends white light and that each color refracts at a different angle depending on the wavelength of the color.

If we think back to our science days we can remember what light really is, that being electromagnetic radiation.  However, because the cone-shaped cells in our eyes are tuned so precisely we can only see a narrow band of that spectrum.  We call this spectrum the visible light spectrum.  Issac Newton showed us that if we shine the full spectrum of visible light or white light through a prism, the wavelengths (A wavelength is the distance from crest to crest) separate into the colors of the rainbow.  This is because each color of the rainbow corresponds to a different wavelength.  Does the acronym ROYGBIV ring any bells?  Violet has the shortest wavelength, at around 380 nanometers and red has the longest wavelength, at around 700 nanometers.  
  

A visual depiction of wavelength as it corresponds to the visible light spectrum.

So how come the moon shines blood red during a full lunar eclipse?  Well for the same reason the sky shines blue on a clear day because sunlight is bouncing off the air in our atmosphere and preferentially bounces blue light.  This is because our atmosphere is made mostly of nitrogen and oxygen.  The shortest wavelengths, indigo and violet (blue light) are more efficiently scattered than the longer wavelengths because they are closer to the size of the molecules.  In other words, the particles that make up our atmosphere are about as small as the wavelength of blue light.  
 

But wait…
 

So how does the blue sky relate to the red moon during a lunar eclipse?  Well for the same reason the sunset is red!  The red seen at sunset is what is left after all of the blue light has been scattered out of the incoming sunlight.  Because at sunset the light is passing through our atmosphere lower on the horizon it passes through a much larger column of air than at noon.  What we see at sunset is the residue light after it has already scattered out all of its blue light, and in turn what is left is the longer red wavelengths. 
  

The Answer!
 

The moon shines blood red during a full lunar eclipse because the only sunlight that reaches its surface has passed completely through the Earth’s atmosphere where the blue light has been scattered out by the Nitrogen and Oxygen in our atmosphere leaving only a residue of red wavelengths.  This residue of sunlight then comes into contact with the Moon where it is reflected back towards Earth, passes again through our atmosphere further depleting it where the light is finally absorbed by passing through a small hole in our eyeball where it is received by a few cone shaped cells at the back of our eye processed by our brain where we measure the wavelength and have an aha moment, the moon is red!  Wait, why is the moon red?

A Short Break in the Clouds - StarLog 09/17/2014

While making the drive back to my apartment this morning I noticed a clear patch of sky so I made the quick decision to attempt a brief star gazing session.  Ever since I got my new pair of astronomy binoculars (Orion 25x100) I have been looking for breaks in the weather so I can try them out.  Unfortunately the clouds have been very persistent so far this September. 

I did not record the exact time of my observations but it was between 05:30:00 and 07:00:00 facing east.  Below is a screenshot taken from Stellarium of what the night sky would have looked like had there been clear skies.  I was only able to view a few dozen of the brightest stars.  

Screenshot taken from Stellarium of my view of the night sky.

A visual of the cloud cover that plagued my observations.

Orion's Belt (or the Belt of Orion)

 My first observation was of Orion’s belt or the Belt of Orion. The constellation consists of the three very bright stars, Alnitak, Alnilam and Mintaka. 

Alnitak is the lower of the three stars and is actually a multiple star system consisting of at least three stars, a possible 4^th has not yet been confirmed! Source  Two stars define the axis of the triple star system.  The largest is a blue supergiant which is estimated to have a diameter that is 20 times that of our own Sun.  I added a size comparison that I took off of Wikipedia to help visualize this behemoth of a star, see below. Source The smaller axial star is a blue dwarf, while the third guy who makes up the triple star system is another blue dwarf and it takes him 1,500 years to orbit both his twin and the massive blue supergiant. 

Visual of Alnitak's blue supergiant star next to our own star, the Sun. Source

Alnilam is the central star in the constellation and is a blue supergiant.  What is so cool about this star is the sheer distance from us (Earth).  From our point of view the star is nearly as bright as the rest of Orion’s belt, but in fact Alnilam is nearly twice as far from our Sun as both Alnitak and Mintaka!  Because our ability to see an object in the night sky is dependent on the distance, the size and the luminosity this tells us that Alnilam is very, VERY bright!  It is also very massive, so large that it cannot contain itself and is losing mass around 20 times more rapidly than our own Sun.  This baby of a sun (four million years old) is expected to transition into a red supergiant and go critical (supernova) in the next few million years. Source

Mintaka is the northwestern most star and consists of a multiple star system.  The system contains a large blue giant and a larger white star.  Mintaka is the dimmest star in the constellation because the stellar system passes in front of itself in what is termed an eclipsing binary variable star.  Wikipedia tells me that this is when one star orbits in front of the other dimming the light from the system.  Source

Orion Nebula (Messier 42)

Moving south from Orion’s belt I made my way to the Orion Nebula or Messier 42.  This was my first experience with deep sky objects and I was not disappointed.  Although visually it just looked like a fuzzy faint cloud it was the awareness of what I was seeing that blew me away.  I was looking at the brightest, youngest and closest star-forming region to Earth.  The object consists of clouds of gas, dust and ionized volumes of more gas all of which are violently mixing to form thousands of new stars in what has been aptly dubbed, a stellar nursery. Source 

Orion Nebula as seen by Hubble.  Source

Orion Nebula through 6-inch refractor telescope, very similar to my view. Source

Moon

Full moon image from Nasa. Source

 

The view I resolved through the lens of my iphone 4S looking through one of the eyepieces of my Orion 25x100s.

The view as seen with my eye is significantly better and the binoculars provided a very crisp and clean image that I was very happy with.  I was able to see craters, mountains and could clearly depict topography on the surface of the moon. 

Something to think about when looking up at the moon is just how far out there in space it actually is.  It may look large compared to all the other objects, but it only covers a very small patch of the night sky.  So small in fact, that with your arm extended you can cover up the Moon with your pinky finger!  The image below helps you wrap your mind around the vast distance between Earth and the moon.  Within that distance all the planets of our solar system could fit!

  An image I got off the front page of Reddit a while back. 

Average distance between the Earth and the Moon with all the planets of our solar system contained between.

Jupiter

Image of Jupiter and two of the Galilean Satellites taken by Hubble.   

Image taken by anonymous amateur astronomer of Jupiter and all four Galilean Satellites.

Screenshot taken from Stellarium of Jupiter and its moons similar to my view.

 

The planet Jupiter is the fifth planet out from our Sun, and is regarded as a “gas giant”.  This is because it has no solid rocky surface like we have here on Earth.  Speaking of Earth, more than 1,000 Earths would fit inside the volume of Jupiter!

Another interesting fact that I find especially fascinating about this planet is that it has the shortest day of all the planets: 9 hours and 55 minutes.  This spin is so fast that it flattens Jupiter at the poles and gives the planet an oblate shape. Source

Quick thought experiment.  Image that Jupiter did have a solid surface and you were standing on it.  Then imagine that suddenly Jupiter stopped rotating, instantly.  You would find yourself hurtling through the atmosphere of Jupiter at over 28,000 mph or roughly 19 times as fast as an F-16 fighter jet!

Because Jupiter is so large its gravitational pull attracts a lot of stuff.  The planet has a thin ring system and 67 known moons!  I was able to see four, the Galilean Satellites: Io, Europa, Ganymede and Callisto.  Europa is of particular interest to the scientific community because it has a large ocean beneath its icy surface. Here on Earth where there is water there is life, which leads one to speculate about what might be swimming around beneath the surface of Europa.

NASA images of the Galilean Satellites: Io, Europa, Ganymede and Callisto.

Despite poor visibility I am pleased with what I was able to observe.  I find that the most enjoyable part of looking up is trying to wrap my head around what it is exactly that I am looking at.  The experience is both incredibly exciting and humbling at the same time.  After all we are all just riding through space on a pale blue dot...

 

Carl Sagan - Pale Blue Dot